CRIME ANALYSIS FOR PROBLEM SOLVERS
In 60 Small Steps 

Ronald V. Clarke & John E. Eck 

Center for Problem Oriented Policing 

U.S. Department of Justice 
Office of Community Oriented Policing Services 


This project was supported by cooperative agreement #2003CKWXK048 by the Office of Community Oriented 
Policing Services, U.S. Department of Justice. The opinions contained herein are those of the authors and do not 
necessarily represent the official position of the U.S. Department of Justice. References to specific companies, 
products, or services should not be considered an endorsement of the product by the author or the U.S. Department 
of Justice. Rather, the references are illustrations to supplement discussion of the issues. 


Crime Analysis for Problem Solvers 
In 60 Small Steps 

Image of Problem-Solving Triangle

Ronald V. Clarke
John E. Eck


Acknowledgments

This is a revised and extended version of a manual, Become a Problem-
Solving Crime Analyst, that we wrote for the Jill Dando Institute of Crime 
Science at University College London, with financial support from the 
Home Office. We are most grateful to the Institute and to the Home Office 
for allowing us to produce this version for the United States. We are also 
grateful to the Office of Community Oriented Policing Services for 
commissioning the work. In the Acknowledgements page of the earlier 
version we thanked many colleagues and friends on whose work we had 
freely drawn. Those who have materially assisted us in completing this 
version by supplying material for inclusion, commenting on drafts, or in 
other ways, include: Stacy Belledin, Rachel Boba, Karen Bullock, Barbie 
Brookover, Christopher Bruce, Andy Brumwell, Graham Farrell, Rob 
Guerette, Samantha Gwinn, Shane Johnson, Johannes Knutsson, Gloria 
Laycock, Nancy Leach, Deborah Loewen, Tamara Madensen, Mangai 
Natarajan, Cynthia Pappas, Ken Pease, Nanci Plouffe, Barry Poyner, Jerry 
Ratcliffe, George Rengert, Nick Ross, Kim Rossmo, Rana Sampson, 
Matthew Scheider, Karin Schmerler, Michael Scott, Nick Tilley, Susan 
Wernicke, Matt White, and Deborah Lamm Weisel. We thank all of them. 


Authors

RONALD V. CLARKE

Ronald Clarke is university professor in the school of Criminal Justice at Rutgers, 
The State University of New Jersey, and visiting professor at the Jill Dando 
Institute of Crime Science, University College London. He worked for many years 
in the Home Office Research and Planning Unit, where he contributed to the 
development of situational crime prevention and the British Crime Survey. He is 
associate director of the Center for Problem-Oriented Policing and chair of the 
judges for the annual Herman Goldstein Award for Excellence in Problem-
Oriented Policing. He can be reached at: rclarke@andromeda.rutgers.edu. 

JOHN E. ECK

John Eck is professor of criminal justice at the University of Cincinnati. He has 
contributed to the development of problem-oriented policing since 1984 when he 
studied the first full-scale attempt to implement the concept in the United States 
at Newport News, Virginia. He helped to develop a number of now standard 
techniques in problem-oriented policing, including the SARA model and the 
problem analysis triangle. Dr. Eck is an affiliate member of the Center for 
Problem-Oriented Policing. He is a judge for the Tilley Award for Excellence in 
Problem-Oriented Policing. Dr. Eck was a member of the Committee to Review 
Research on Police Policy and Practice (2000-2003) of the National Academy of 
Sciences. He can be reached at: john.eck@uc.edu. 


Foreword

One of the primary concerns in policing in the United 
States today  and for the foreseeable future  is 
the severe constraint on spending. The lion's share 
of police budgets is consumed in personnel costs. As a 
result, many police agencies are already operating 
significantly below their authorized strength. Funds to hire 
new officers to meet growing needs are hard to obtain. 
And, of special relevance here, traditional forms of policing, 
because they are so heavily dependent on personnel, are 
being curtailed. Calls cannot be handled as completely and 
quickly as in the past. Personnel cannot be as freely 
assigned to increasing the police presence on the streets in 
labor-intensive tactics, such as crackdowns, sweeps, and 
special task forces. 

This reality is a powerful new force for rethinking the way 
in which we police. It connects with prior efforts to 
promote greater concern for the effectiveness of the police. 
And it lends fresh impetus to meeting a long-standing, 
neglected need  the need to equip the police with an 
institutionalized capacity to examine its work product; to 
routinely ask, before committing to more of the same, what 
it is that the police are expected to accomplish and how 
they can more effectively accomplish it. 

Rethinking current methods requires a new understanding 
of the role of the police  both on the part of the police 
and the public they serve. It is essential to recognize that 
the police function is not as simple as it is sometimes 
portrayed. It is incredibly complex. It is not a singular 
function, commonly defined as enforcing the law. It 
requires dealing with a broad range of behavioral 
problems, each quite different from the other. It does not 
consist simply of reacting to an endless array of incidents. 
Police are now expected to prevent them from occurring in 
the first instance. 

A fresh perspective on policing requires that the police 
examine, in depth, each of the numerous behavioral 
problems that together constitute their business; that they 
consider a broader range of strategies on how best to 
prevent, reduce, or eliminate each of them; and that they 
weigh more precisely their effectiveness upon adopting a 
new targeted response. This is the essence of problem-
oriented policing. 

Many advances have been realized under the umbrella of 
problem-oriented policing since the concept was first 
introduced in 1979. But these have not been 
mainstreamed within policing. Their implementation has 
been spotty, uneven, and without deep and lasting roots. 
They remain overshadowed by the dominant, continuing 
commitment to traditional policing and its heavy 
dependence on lots of police officers patrolling and 
making arrests. 

Greater concern about police effectiveness in dealing with 
specific behavioral problems need not start from scratch. 
Collectively, we know much about the wide range of 
behavioral problems that constitute police business and 
how best to prevent them. This knowledge can be found in 
the substantial literature on crime and crime prevention  
especially in the literature on situational crime prevention. 
Much of value can be found, too, among the practices of 
police agencies and in the minds of experienced police 
officers, but this experience and expertise must be tapped 
and subjected to rigorous analysis. 

The Center for Problem-Oriented Policing (POP Center) 
(www.popcenter.org) now serves as a locus for the 
collection of the growing body of knowledge regarding 
problems commonly encountered by the police. It 
disseminates this material in various ways, but primarily 
through the publication of its problem-oriented guides. 
Each guide synthesizes existing knowledge and evaluated 
practices regarding a specific problem, and stimulates 
police to advance their own thinking about how best to 
handle the problem in its local context. 

While the POP Center has documented hundreds of 
successful cases in problem-oriented policing, a major 
impediment to advancing the concept has been the 
absence of an analytical capacity within police agencies. 
Many police agencies do employ one or more crime 
analysts, but some of the largest and more advanced police 
organizations do not. When employed, the job of the crime 
analyst is often narrowly limited to tabulating crimes that 
occur. In others, it extends to identifying patterns of crimes 
with the primary objective of identifying the likely offender 
so that he/she can be apprehended. In its more ambitious 
form, the crime analyst's job may include identifying factors 
contributing to a crime pattern, but the job of deciding 
how to respond to these factors is usually deferred to 
operational personnel, who then tend to use traditional 
means for dealing with them. 


Meanwhile, the field of crime analysis itself has grown 
much more sophisticated. A strong literature on its 
potential is now available. The ability to electronically 
capture, store, and retrieve massive amounts of data that 
police routinely collect is infinitely greater than it was just 
a decade ago. The capacity to map crime geographically is 
stunning, and is now a major, indispensable tool in crime 
analysis. Standard approaches have been developed for 
the collection, analysis, and dissemination of intelligence 
across jurisdictional lines. 

In this manual, Ronald Clarke and John Eck set out a 
much more ambitious and potentially productive agenda 
for the analyst. They outline a role in which the crime 
analyst invests heavily in seeking new responses to the 
problems that are diagnosed and participates directly in 
efforts to test and implement them. The analyst is 
expected to contribute to exploring new, more creative, 
and potentially more effective ways of carrying out the 
police job. Through this manual, Clarke and Eck 
demonstrate how one analyst, properly trained and 
utilized, has the potential to increase many times the 
productivity and effectiveness of perhaps hundreds of 
police officers. Understood in this way, an investment in 
crime analysts can be a smart way to increase the return 
on the substantial investment that communities make in 
sworn police personnel. 

Blending their expertise as researchers and their 
familiarity with policing, Clarke and Eck have collected all 
of the knowledge and methodology that is relevant and 
currently available; organized it in 60 small segments or 
steps that build logically upon each other; and 
communicated the material in a style that is both concise 
and engaging. The volume is packed with vital and 
sophisticated information that makes it one of the most 
significant publications addressed to the policing field in 
the past several decades. 

The most immediate goal of the manual is to help the 
relatively small number of individuals now commonly 
employed in police agencies as crime analysts to expand 
their function and thereby contribute more to the 
effectiveness of their agency's operations. It is intended, 
more ambitiously, to contribute to the training of new 
crime analysts or problem-solvers, to increasing their 
number, and to their development as a distinct and vital 
profession. But problem analysis is not the exclusive 
domain of technicians. We hope that, everyone else in a 
police agency, from officers on the beat to police 
executives, and, more broadly, those in both the public 
and private sector concerned about crime, will incorporate 
the line of thinking set forth in the manual into the 
perspectives they bring to their work. 

Herman Goldstein 
Professor of Law Emeritus 
University of Wisconsin-Madison 


Read this first

This 60-step manual assumes that you are an 
experienced analyst and that you are accustomed to 
providing the kind of information needed to support 
police operations. This means that: 

1. You use modern computing and know how to access 
and manipulate comprehensive databases. 

2. You know how to use software to map crime, to 
identify hot spots, and to relate these to demographic 
and other data. 

3. You routinely produce charts showing weekly or 
monthly changes in crime at departmental and beat 
level, perhaps to support CompStat-style operations. 

4. You are accustomed to carrying out analyses into such 
topics as the relationship between the addresses of 
known offenders and local outbreaks of car theft and 
burglary. 

5. You may have carried out some before-and-after 
evaluations of crackdowns, such as on residential 
burglaries or car thefts. 

6. You have some basic knowledge of statistics and 
research methodology such as is provided by an 
undergraduate social science degree. 

The manual builds on this experience to prepare you for a 
different analytic role as a key member of a problem-
solving team. Indeed, the latest writings on problem-
oriented policing see crime analysts as central to this new 
way of policing communities. These writers argue that 
many of the weaknesses of current practice result from 
the insufficient involvement of well-trained crime analysts 
at each stage of the problem-solving process. 

The manual prepares you for this new role by providing 
you with a basic knowledge of problem-oriented policing 
and the related fields of environmental criminology and 
situational crime prevention. You cannot adequately 
function as a problem-solving crime analyst without being 
conversant with these fields. Nor can you fill this role 
without rethinking your job, and the early sections of the 
manual explain how to take a more proactive approach. 
You cannot simply wait for your police colleagues to come 
to you with requests for information. Instead, you must 
take the initiative at every stage of the project in defining 
the scope of the problem-solving effort, in trying to 
analyze the causes of the problem, in helping to find an 
effective response, and in setting up the project so that it 
can be evaluated and the police can learn from the 
results. This means that you must be an integral member 
of the problem-solving team, that you must explore 
sources of information and data well beyond those that 
you normally use in your work, that you must stick with a 
particular project much longer than you normally would 
and, finally, that you will share the credit for its success, or 
the disappointment for its failure, equally with the other 
members of the team. 

The manual assumes that analysts who take on this new 
role are interested in contributing to the development of 
their profession. Assisted by vastly improved data-bases 
and powerful computing hardware and software, crime 
analysis is on the verge of becoming an exciting new 
specialty. Indeed, it has already begun to attract a cadre 
of well-trained and highly motivated professionals who 
are vital to the development of policing in the 21st 
century. You can make your contribution by 
communicating the results of your work in professional 
meetings and in the journals of your profession. By doing 
so, you will not only help your profession and policing in 
general, but you will become a more informed and 
valuable resource to your own force. 

The manual is short enough to get through in a weekend. 
It would be hard work and probably worth doing, but it 
was not designed to be read and then shelved. Instead, 
we hope that you will find it to be an indispensable 
reference source that you will keep near your desk, 
consulting it whenever needed in the course of a 
problem-solving project. This is why it is designed to be 
robust, allowing for continuous use. When open at a 
particular step it is designed to lie flat on your desk so 
that you can consult it easily when working at 
your computer. 

We have arranged the steps to follow logically one from 
another, in line with the SARA model (Scanning, Analysis, 
Response and Assessment), though each is self-contained 
and deals with a specific topic. This should make it 
unnecessary for you to leaf through the manual, jumping 
from place to place, when dealing with a particular topic. 
To get the best out of the manual you should be 
thoroughly familiar with the list of contents and you 
should have browsed through sections that interest you to 
get an idea of the coverage. But you need only study a 
particular step when you have an immediate need for the 
information it contains. In any case, this is the best way to 
learn: to seek and apply information when you have a 
practical need for it. 


In some cases, we do deal with a particular topic in more 
than one place. For example, Step 12 provides a general 
introduction to the concept of displacement, while Steps 
48 and 49 explain how to check for various forms of 
displacement at the evaluation stages. The combined 
glossary and index at the end of the manual should help 
you find where a topic is mentioned in more than 
one place. 

We use examples from other countries as well as from the 
United States. We sought the best examples to make our 
point, so even if the context is foreign, the principles are 
universal. We hope this diversity of ideas stimulates 
creative thought: "Could that approach be adapted to 
this problem? How could we do it?" 

We have not referenced the manual as fully as an 
academic publication for several reasons. We have already 
tried to distill the essentials of the literature at each step. 
We also doubt that busy crime analysts will have much 
time for academic reading. Lastly, few of you will have 
ready access to the specialized libraries that hold this 
material. But occasionally you will need to know more 
about a topic, and at each step we identify key articles or 
books that you should be able to obtain more easily. 
Where possible, we have chosen those that are accessible 
on the Web. If you need help with references, feel free to 
email one of us at the addresses given earlier. We would 
also be glad to receive any comments on the manual, 
especially suggestions for improvement, which could be 
useful if we prepare later editions. Most important, please 
don't be shy about suggesting your own analyses 
for inclusion! 

The Home Office and the British Police 

As explained in the Acknowledgements, we have developed this manual from an earlier version that we 
prepared for the Jill Dando Institute of Crime Science at University College London. We have removed 
British terms and spelling and have replaced many of the British examples with American ones. But you 
will still find many references to things British. In particular you will see frequent mention of the Home 
Office, which is equivalent to the U.S. Department of Justice. It has overall responsibility for matters 
relating to crime and justice in England and Wales, including the police. There are only 43 police forces in 
England and Wales (for a population of about 50 million), so the forces are much larger than most 
American police departments. There is also much more uniformity among British police forces in policies, 
rank structures, equipment, and deployment. This is partly due to the oversight provided by the Home 
Office (which provides 51 percent of each force's budget) and regular inspections by Her Majesty's 
Inspectors of Constabulary. The Home Office also funds a great deal of research on crime and criminal 
justice and has its own large research department that publishes many studies of direct, practical 
relevance to police. Recently, it has sponsored much work on problem-oriented policing, including the 
original version of this manual. 



TABLE OF CONTENTS

Acknowledgements 

Authors 

Foreword 

Read This First 

Prepare Yourself 
1. Rethink your job 
2. Be the local crime expert 
3. Know what is effective (and not) in policing 

Learn About Problem-Oriented Policing 
4. Become a POP expert 
5. Be true to POP 
6. Be very crime specific 
7. Be guided by SARA - not led astray! 

Study Environmental Criminology 
8. Use the problem analysis triangle 
9. Know that opportunity makes the thief 
10. Put yourself in the offender's shoes 
11. Expect offenders to react 
12. Don't be discouraged by the displacement doomsters 
13. Expect diffusion of benefits 

Scan for Crime Problems 
14. Use the CHEERS test when defining problems 
15. Know what kind of problem you have 
16. Study the journey to crime 
17. Know how hot spots develop 
18. Learn if the 80-20 rule applies 

Analyze in Depth 
19. Research your problem 
20. Formulate hypotheses 
21. Collect your own data 
22. Examine your data distributions 
23. Diagnose your hot spot 
24. Know when to use high-definition maps 
25. Pay attention to daily and weekly rhythms 
26. Take account of long-term change 


27. Know how to use rates and denominators 
28. Identify risky facilities 
29. Be ready for repeat victimization 
30. Consider repeat offending 
31. Know the products that are CRAVED by thieves 
32. Conduct case control studies 
33. Measure association 
34. Look for crime facilitators 
35. Understand the crime from beginning to end 
36. Be sure to answer the five "W" (and one "H") questions 
37. Recognize that to err is human 

Find a Practical Response 
38. Embrace your key role at response 
39. Increase the effort of crime 
40. Increase the risks of crime 
41. Reduce the rewards of crime 
42. Reduce provocations 
43. Remove excuses for crime 
44. Find the owner of the problem 
45. Choose responses likely to be implemented 

Assess the Impact 
46. Conduct a process evaluation 
47. Know how to use controls 
48. Consider geographical and temporal displacement 
49. Examine displacement to other targets, tactics and crime types 
50. Watch for other offenders moving in 
51. Be alert to unexpected benefits 
52. Expect premature falls in crime 
53. Test for significance 

Comunicate Effectively 
54. Tell a clear story 
55. Make clear maps 
56. Use simple tables 
57. Use simple figures 
58. Organize powerful presentations 
59. Become an effective presenter 
60. Contribute to the store of knowledge 

Glossary/Index 


1. Rethink your job

Like most crime analysts, you probably think of your 
job in rather modest terms. You do not solve crimes 
single-handed. Nor do you take the lead in setting 
departmental crime-fighting priorities. Instead, you crunch 
data for those who do the "real" work of finding better 
ways to arrest criminals. You respond to requests for the 
latest statistics on burglary or car theft from beat officers 
and sergeants. You map crime for weekly meetings so that 
the lieutenant knows where to demand more effort. And 
you compile monthly statistics that others need for their 
reports. In other words, you sit in the back seat while 
others do the driving, asking for your help only when they 
need it. 

This manual will help you rethink your role. Even someone 
sitting in the back seat can help the lost driver find 
direction. Control over information is crucial, and the 
ability to analyze it is all-important. The person who 
learns how to do so becomes an essential member of the 
team. But we are not talking here about power or status. 
We are referring instead to a challenge facing all police 
forces: how to solve enduring and repetitive crime 
problems. Think of yourself as a member of a team 
helping to solve these problems, with a particular role in 
that team. As you use this manual you will begin to see 
how to perform that role and you will also see how 
essential it is. 

To play that essential role, you need to know more. We 
are not referring to improved computer skills or mapping 
ability, important though these are. You need to learn 
more about crime itself, to become a resource to your 
department as an expert on crime in your local area. If 
there is a new burglary wave, you should be the first to 
know and the first to tell. Analyze and map the statistics 
and get the basic facts yourself. If you wait, others will say 
what is happening without any factual basis. Once more 
you will be relegated to the back seat. You are the "facts" 
person and you must find things out as soon as possible, 
using the best means possible. This will often mean going 
beyond police data, and this manual will tell you how to 
use other data sources, including interviews with victims 
and offenders and records of crime kept by businesses. 
Becoming a source of information is a first step. The ideal 
is to also be a source of advice. Whether you can do this 
depends on your supervisor's openness, but at least you 
can provide options or support the suggestions of others 
with information and data. 

In particular you should know what works in policing and 
what does not. How effective is random patrol? How 
often do police come upon a crime in progress? How 
often are crimes solved later through patient detective 
work or forensic evidence? How productive are stakeouts 
and surveillance in terms of arrests? How much do 
crackdowns cost in officers' time? What are the arrest 
rates for different kinds of crimes? How many crimes of 
different kinds are even reported to the police? Knowing 
answers to these questions will tell you why even the 
most hard-working officers are relatively ineffective in 
preventing crime, and why an increasing number of police 
forces are now turning to problem-oriented policing. 

The main purpose of this manual is to tell you about 
problem-oriented policing and the vital part you can play 
in its implementation. The manual helps you distinguish 
problem-oriented policing from other forms of community 
policing. It shows you how problem-oriented policing can 
become more effective by using environmental 
criminology and situational crime prevention. It describes 
each of the four stages of a problem-oriented project scanning 
for crime problems, analyzing a specific problem 
in depth, responding to the problem by implementing 
solutions and assessing the results of the project - and 
gives examples of the data and information that you 
could provide at each stage. Finally, it illustrates the kind 
of analyses that you can undertake at all four stages to 
work effectively as a member of the 
problem-solving team. 

These stages of a problem-oriented project will require 
that you remain working on a single project much longer 
than your traditional analytic role requires. You can expect 
to stay with a problem-solving project for weeks or 
months, rather than just the few hours needed to plot a 
burglary hot spot or provide a monthly report. Where a 
detailed assessment of results is needed, your involvement 
might even stretch for more than a year. You may have to 
explain this to officers who come to you for help. At first 
they may be surprised that you expect to stick so long 
with a project, but soon they will appreciate your 
commitment to making the effort worthwhile. 

Your time has been wasted if you cannot communicate 
the results of your work. Later sections of the manual give 
suggestions for communicating more effectively by telling 
a story using simple maps and tables. Your presentations 
should try to lead to a course of action, but you must 
always explain the limits of your data and tell officers 
where your recommendations are based on best guesses 
rather than facts. 


This manual cannot tell you everything you must know or 
do to become a problem-solving analyst. You must seek 
constantly to enhance your professional and technical 
skills and keep up-to-date with the latest developments in 
relevant fields. You must take the initiative in finding more 
effective ways to capture information and more efficient 
ways to process it, as time freed up from routine tasks 
means more time for the new work of problem analysis. 
You must read more widely and explore other sources of 
information. Additional readings are recommended 
throughout this manual, but you will also have to find 
material for yourself. A good way to do this is through 
networking with analysts in other departments and by 
attending professional meetings of analysts, police and 
criminologists. And try to pass on lessons you have 
learned by making presentations at these meetings of 
valuable or novel analyses you have undertaken. 

In short, you should begin to see yourself as more than 
just a technician, skilled in manipulating and presenting 
data. You should become more like a researcher - albeit 
with a highly practical focus - one who is bringing the 
very best that science can offer to make policing more 
effective. By the same token, also recognize that you are 
part of an emerging profession, which you can help 
to develop. 

Rethink your job: 

 Become a crime expert 
 Know what works in policing 
 Promote problem solving 
 Take your place on the project team 
 Learn about environmental criminology 
 Hone your research skills 
 Communicate effectively 
 Enhance your profession 

Read More: 

Braga, Anthony (2002). Problem-Oriented Policing and 
Crime Prevention, Monsey, NY: Criminal Justice Press. 


2. Be the local crime expert

How often have you been asked the following sorts 
of questions in your work? 

 What locations are hot for auto theft right now? 

 Which convenience stores are repeatedly robbed 
and why? 

 What are burglars taking from shops and where do they 
fence the goods? 

 Is there less crime in the better-lit streets? 

 Which apartment complexes harbor drug markets? 

Some of these you might not have been able to answer at 
all - others only after a special analysis. But suppose you 
had the answers to them and many more at your 
fingertips? Suppose you were the expert on crime in your 
force area? In fact, nobody else can fill that role: 

 Individual officers are too busy answering calls. 

 Detectives are focused on specific cases. 

 Sergeants are supervising their officers. 

 Lieutenants are overseeing patrol responses for large 
geographic areas. 

 The chief, his or her assistants and captains are busy 
with administrative issues. 

In short, nobody can see the whole crime picture. But if 
you became the local crime expert it would help make 
your department more informed, efficient, and capable of 
using its resources to reduce crime. It would provide more 
opportunity to warn citizens, to detect offenders, and to 
initiate prevention efforts. In short, you could help a lot of 
people by gathering the right information. 

To become the local crime expert, sit in regularly with 
dispatchers and talk to officers about what they are 
seeing. Remember the late shift might not see officers on 
the early shift, and those on one side of town might not 
see officers on the other. They often talk about exceptions, 
not the rules, about what made them angry, not about the 
routine. Yet the routine is the bread and butter of 
crime analysis. 

Take ride-alongs as often as time permits. Not only will 
you get to know more of the officers in your department, 
but you will also get a better feel for their work and the 
problems they face on the street. Matt White, crime 
analyst with the Jacksonville, Florida Sheriff's Office, 
recommends taking along a laptop loaded with 
Geographic Information System (GIS) data. You can then 
compare information about the area with the 
officers' perceptions. 

Crime scenes receive a good deal of attention in serious 
crimes, but not usually in ordinary crimes. You can learn a 
lot by visiting them, especially when trying to understand 
a particular crime problem. Comparing incident reports 
with your own observations could reveal that important 
details about the setting and the circumstances of 
incidents might not have been recorded - perhaps 
because the report form did not specifically request them. 
Armed with this knowledge, you can suggest changes to 
the forms to capture information that is helpful both for 
detecting offenders and for thinking about how to prevent 
these crimes in the future. 

Try to keep abreast of new trends in crime. Read through 
a batch of crime reports each week to see if there is 
anything new. Try also to pay attention to failed crime 
attempts (see box). Some offenders have a trial-and-error 
process as they look for new ways to get something for 
nothing. Those trying to cheat ticket vending machines or 
ATMs may have difficulty in finding a method that works. 
But when they do, the word will spread. If you know their 
method, you might be able to warn officers and others. 

Very often a local crime problem is also found elsewhere. 
Your force may experience a rash of thefts from building 
sites when this has never been a problem before. But you 
can be sure that somewhere else has suffered this 
problem. That's why it is important to be alert to changes 
in crime targets and modus operandi. The Internet is a 
good source of information about what crime others are 
seeing. You should also ask your analyst colleagues in 
nearby forces. They may be experiencing exactly the same 
problem, with perhaps the same group of 
offenders involved. 

Do not limit yourself to the police because many other 
people know a lot about particular crime problems: 

 City code inspectors can see blight developing before 
this is apparent to others. 

 Bar owners know about underage drinking, poor serving 
practices and sloppy management (in other bars, of 
course!). 

 Principals know all too well about bullying and 
vandalism on school premises. 

 Small business owners are alert to problems involving 
their premises. For example, a pharmacist knows what is 
being stolen from his shop or whether intoxicated 
people are hanging out nearby. 

 Emergency room personnel see many injuries from crime 
that they record but might not report to the police. 


 
Women's refuges or rape crisis centers know far more 
about patterns of domestic violence than most 
police officers. 
 
Private security guards are often the first to know about 
a particular incident. But they also have information that 
can contribute to your general understanding of local 
crime patterns. 

Offenders themselves are surprising sources of 
information. Although they might not admit doing 
anything themselves, they are often willing to talk about 
"how it is usually done." Many offenders are actually 
quite talkative about the craft of offending, and will tell 
you exactly how they pick targets, fence valuables, what 
offenders are looking for these days, and the like. Asking 
your police colleagues to obtain this information from 
offenders can sometimes be very useful. 

Last, victims can tell you a good deal about the crime. For 
offenses such as burglary, they may not be able to give a 
precise time of offense, but they can still tell you where 
an offender broke in, what is missing, what room or floor 
was left alone, etc. 

How to become expert on crime in your area: 

 Get away from your computer! 
 Talk to officers about what they are seeing. 
 Go on ride-alongs and sit with dispatchers. 
 Visit crime scenes and examine crime reports. 
 Check failed attempts to learn exactly what happened. 
 Talk to city officials about specific crime problems. 
 Exchange information with businesses and private security. 
 Ask analysts in nearby cities about changes in crime targets and methods. 
 Ask officers to question offenders about their methods. 
 Get information from victims about exactly when, where, and how. 
 Help to improve crime incident forms and data capture. 

Learning from Unsuccessful Attempts 
The Chula Vista, California Police Department was aware that the city's building boom could worsen the residential burglary 
problem. The new houses were intended for affluent couples who would be out during the day when burglaries were most likely 
to happen. The police, therefore, decided to examine the effectiveness of existing security precautions to see if any of these could 
be built into new homes or suggested to homeowners. Cathy Burciaga, one of the department's crime analysts, compared 
completed burglaries with unsuccessful attempts for an 18-month sample of 569 homes in the city. This indicated that deadbolts 
should be installed on both the side and front doors of new houses. Interviews conducted with 250 victims and 50 burglars 
revealed that not one burglar had tried to enter a house by breaking a double-glazed window. This led to the recommendation 
that all windows in new housing be double-glazed and meet strict forced-entry standards. 

Table Headers - Completed Burglaries, Unsuccessful Attempts, Effective?* 
Row Data -  
Dusk to dawn light 28%, 29%, No
Indoor light on 26%, 29%, No
Indoor timer light 9%, 11%, No
Deadbolt on front door 28%, 25%, No
Deadbolt front & side doors 15%, 29%, Yes
Outdoor motion detector 23%, 36%, Yes
Radio/TV left on 9%, 18%, Yes
Alarm company sign 19%, 36%, Yes
  
*"Yes" means present in a larger proportion of unsuccessful attempts than completed burglaries. 


3. Know what is effective (and not) in policing

Evidence on what makes police effective points to the 
vital role of crime analysis in 21st century policing. 
Understanding this research can help you apply the 
lessons the police profession has learned over the last 
third of a century. 

There has been considerable research into which police 
practices are effective at reducing crime and which 
practices are not effective. Recently, the National Academy 
of Sciences established a panel of social science experts to 
review all police research including the question of police 
effectiveness. The figure is adapted from this report. The 
least effective approaches to crime reduction are in the 
lower left quadrant and the most effective are in the 
upper right. 

In the lower left corner of the figure, we have the 
"standard model" of policing. This is the dominant 
policing strategy in North America. The standard model is 
characterized by its reliance on law enforcement and a 
lack of focus. Here we find general patrolling to deter 
offenders, rapid responses to a wide variety of calls for 
police service, follow-up investigations of crimes, and 
other law enforcement activities that make little 
distinction among the characteristics of the people, places, 
times, or situations. Faced with a public demand to reduce 
crime, public officials and the press who are wedded to 
the standard model will request more police officers, 
decreases in response time, greater police visibility, higher 
success rates in investigations, and more arrests. Equally 
important is what the press and public officials do not call 
for - increased precision as to who, what, when, where, 
why, and how crimes take place, distinctions among crime 
types, the involvement of other public and private 
institutions to address crime, or the application of non-law 
enforcement alternatives. 

Some of the earliest research into police effectiveness 
addressed aspects of the standard model. This research 
has consistently failed to find that the standard model has 
any noticeable effect on crime, disorder, or fear of crime. 
Random patrol, rapid response, follow-up investigations, 
and arrest policies may be very beneficial for other 
purposes, but we should not expect any of these practices 
to have an impact on crime or disorder. Nor is there solid 
evidence that adding police to carry out these practices 
will affect crime. 

To have an effect on crime, research strongly suggests 
that police strategies must include two elements. These 
are represented on the axes of the figure. First, the 
strategy must diversify its approaches to crime and 
disorder. That is, policing must address crime and disorder 
using a greater range of tools than simply enforcing the 
law. This idea is expressed on the vertical axis. There is 
evidence that working with the public, and going beyond 
law enforcement, can have modest crime and disorder 
reduction affects, and the more personal the police-citizen 
contacts the more likely it is that they will have an effect 
on crime. 

The second element necessary to highly effective policing 
is focus. This element is expressed in the horizontal axis of 
the figure. There is generally solid evidence that 
geographically concentrated enforcement at crime or 
disorder hot spots can be effective, at least in the short 
run. That is, focused patrolling of very small high-crime 
places (e.g., street corners and block faces) has a modest 
effect on crime and a large effect on disorder. This can be 
accomplished with or without intensive arrest actions. 
CompStat and other related innovations of the late 1990s 
seek to take advantage of these findings. The Office of 
Community Oriented Policing Services has published a 
Problem-Oriented Guide about when crackdowns and 
related tactics are and are not effective (see Read More). 

If a few individuals are responsible for most crime or 
disorder, then removing them should reduce crime. Though 
sound in principle, the research testing this idea is very 
poor so we do not know whether repeat offender 
programs work in actual practice, or if they are a 
seemingly promising notion that cannot effectively be 
carried out. 

Problem-oriented policing applies both elements combining 
the use of diverse approaches with focused 
action. How effective is it? There is a large body of 
evaluation evidence here applying weak-to-strong 
research methods that consistently finds that this 
combination does reduce crime and disorder. First, many 
problem-solving efforts have been applied after 
concentrated enforcement has failed to produce long 
lasting effects on crime, so something else needs to be 
done. In one of the earliest examples, police in Newport 
News, Virginia, had been struggling with the exceptionally 
high burglary rate in the New Briarfield apartments for 
well over a decade. They had obtained some short-term 
results from various enforcement methods, such as foot 
patrols and mini-station programs. But each time the 
police redeployed away from New Briarfield the burglary 
rate surged. It was only after applying a problem-oriented 
approach - involving citizens, the public housing authority, 


Crime Analysis for Problem Solvers in 60 Small Steps 
PREPARE YOURSELF 
the fire department, the city codes department, and the 
U.S. Department of Housing and Urban Development that 
they were able to substantially reduce burglaries. 
Second, when problem-solving at drug hot spots was 
compared to traditional law enforcement at drug hot 
spots in a Jersey City, New Jersey, randomized experiment, 
David Weisburd and Lorraine Green found that problem-
solving had the greater impact. So, even though focused 
law enforcement is more effective than unfocused law 
enforcement, focused problem-solving is even 
more effective. 

The lessons during a third of a century of research are 
now clear. Effective police work requires both focused 
attention and diverse approaches. The least effective 
policing uses neither element. The explanation for this is 
also clear. If diverse approaches are used without focus, it 
is difficult to apply the appropriate approach to the places 
and people who most require it. If police are focused on 
hot spots, but only enforce the law, they limit their 
effectiveness. A fully effective police agency must take 
advantage of the details of crime situations to reduce 
crime opportunities. Crime analysts have important roles 
in applying both elements - focusing with precision using 
their analytical methods, and helping to craft appropriate 
police tactics that fit the details of problems they have 
uncovered. This makes the 21st century the century of 
crime analysis in policing. 

Read More: 
Scott, Michael (2003). The Benefits and Consequences of 
Police Crackdowns. Problem-Oriented Policing Guides. 
Response Guides Series No. 1. Washington, DC: Office of 
Community Oriented Policing Services. (accessible at 
www.popcenter.org and www.cops.usdoj.gov). 

Weisburd, David and John Eck (2004). "What Can Police 
Do to Reduce Crime, Disorder and Fear?" The Annals of 
the American Academy of Political and Social Science 
593: 42-65. 

Effectiveness of Policing Strategies

Great: 
Apply a diverse array of 
approaches, including 
law enforcement

Low Focus
Community Policing 
Little or no evidence of 
effectiveness 
 Impersonal community policing (e.g., 
newsletters) 
Weak to moderate evidence 
 Personal contacts in community policing 
 Respectful police-citizen contacts 
 Improving legitimacy of police 
 Foot patrols (fear reduction only) 

High Focus
Problem-oriented Policing 
Moderate evidence of effectiveness 
 Problem-oriented policing 
Strong evidence of effectiveness 
 Problem-solving in hot spots 

Little: 
Rely almost exclusively 
on law enforcement 

Low Focus
Standard Model 
Little or no evidence of 
effectiveness 
 Adding more police 
 General patrol 
 Rapid response 
 Follow-up investigation 
 Undifferentiated arrest for domestic 
violence 

High Focus
Focused Policing 
Inconsistent or weak 
 Repeat offender investigations 
Moderate to strong evidence of 
effectiveness 
 Focused intensive enforcement 
 Hot-spots patrols 
Low Focus High 

Adapted from National Research Council (2003), Fairness and Effectiveness in Policing: The Evidence. 
Committee to Review Research on Police Policy and Practice. Edited by Wesley Skogan and Kathleen Frydl. 
Washington, DC: The National Academies Press. Figure 6.1 and Table 6.1, pp. 248-249. 
 


4. Become a POP expert

When a serious crime occurs, the police are 
expected to react immediately. They must provide 
help and reassurance to victims and move fast to 
arrest offenders. Yet we have seen that many times the 
police are not able to arrest the culprits and may not be 
able to secure a conviction when they do. We have also 
seen that random patrolling, which the public expects, is 
not an efficient way to apprehend criminals. This means 
that much police work that is carried out to meet public 
expectations is of limited value in controlling crime. 

If they knew these facts, people would not be content for 
police to abandon patrol or down-grade their response to 
serious crimes. Rather, they would expect the police to 
find new and better ways to control crime, while 
continuing their traditional work. In fact, this is what the 
police leadership has been trying to do by experimenting 
with CompStat, zero tolerance, community policing, and 
problem-oriented policing (or problem-solving as it is 
often called). While crime analysts have a role in all these 
innovations, problem-oriented policing (POP) thrusts them 
into the limelight and gives them an important team 
function. That's why you should learn about it. 

Herman Goldstein originated the concept of problem-
oriented policing in a paper published in 1979. His idea 
was simple. It is that policing should fundamentally be 
about changing the conditions that give rise to recurring 
crime problems and should not simply be about 
responding to incidents as they occur or trying to forestall 
them through preventive patrols. Police find it 
demoralizing to return repeatedly to the same place or to 
deal repeatedly with problems caused by the same small 
group of offenders. They feel overwhelmed by the volume 
of calls and rush around in a futile effort to deal with 
them all. To escape from this trap, Goldstein said the 
police must adopt a problem-solving approach in which 
they work through the following four stages: 

1. Scan data to identify patterns in the incidents they 
routinely handle. 

2. Subject these patterns (or problems) to indepth 
analysis of causes. 

3. Find new ways of intervening earlier in the causal 
chain so that these problems are less likely to occur in 
the future. These new strategies are not limited to 
efforts to identify, arrest, and prosecute offenders. 
Rather, without abandoning the use of the criminal law 
when it is likely to be the most effective response, 
problem-oriented policing seeks to find other potentially 
effective responses (that might require partnership with 
others) with a high priority on prevention. 

4. Assess the impact of the interventions and, if they have 
not worked, start the process all over again. 

SARA is the acronym used to refer to these four stages of 
problem solving - Scanning, Analysis, Response and 
Assessment. Later sections of this manual will discuss 
these in detail, but you can already see why you have a 
central role in problem-oriented policing. You are the 
person most familiar with police data and you know how 
best to analyze and map that data to identify underlying 
patterns. You may know better than anyone else in the 
department how to use data in evaluating new initiatives. 
If you make it your business to become the local crime 
expert, you will also know where to find other relevant 
information about problems; where to find information on 
the Internet and in specialist literature about successful 
responses used elsewhere; how to use insights from 
environmental criminology in developing a problem 
analysis; and how to anticipate and measure any possible 
displacement. Without your day-to-day involvement at all 
four stages, the POP project will not achieve a substantial 
and sustained reduction in the problem. 

Problem solving can be difficult. The greatest difficulties 
are found at analysis and assessment, precisely where you 
could make your greatest contribution. Indeed, from the 
very first, Goldstein has argued that problem-oriented 
policing depends crucially on the availability of high-level 
analytic capacity in the department an argument repeated 
in his most recent publications. In fact, he has been very 
supportive of the idea of writing this manual, which is 
addressed directly to the role of the crime analyst in 
problem-oriented policing. 

You might agree that you have a substantial role in 
problem-oriented projects, but you might ask how you 
could ever succeed in that role given the realities of your 
job. How could you devote the time needed for the kind 
of careful analyses required? How could you make a long-
term commitment to a project, when you are continually 
being asked to produce statistical reports and maps 
immediately, if not before? How would you ever be 
accepted as an equal member of the team, especially if 
you are a mere civilian? How could you function as an 
equal member when your boss wants to approve every 
analysis you suggest and wants to see all your work 
before it leaves the unit? How could you restrain the 


natural impatience of officers to move to a solution before 
the analysis is complete? How could you persuade them 
to consider solutions other than identifying and arresting 
offenders? How would you deal with criticisms that you 
are more interested in research than practical action? In 
short, you may be wondering what planet we are living 
on because it certainly resembles nothing you have seen. 

These are good questions, but we believe that policing is 
changing and that you can help speed up these changes. 
There is slow but increasing pressure on police to become 
more effective and the time is long past when chiefs 
could say they would cut crime if only they had more 
resources. Now, at least in larger departments, they must 
make a detailed evidence-based case for these resources 
and must explain precisely how they would use them. 
Their performance is being watched more closely every 
day, and the crime reductions that police in many cities 
claim to have achieved have undermined excuses 
for failure. 

In short, there is no doubt that police will become 
increasingly reliant on data to acquire resources and 
manage them effectively. By providing these data, you can 
ride this tide of change to a more rewarding career in 
policing, though you will have to work patiently to supply 
timely information in a form that is helpful to the 
organization. If you do this, and you remain firmly focused 
on crime reduction, you and your profession will gradually 
move into a more central policing role - and problem-
oriented policing provides you with the perfect vehicle. We 
all know that policing is beset by new fads that follow hot 
upon one another and almost as quickly disappear when 
something new arrives. Many seasoned officers play along 
for a while, waiting for management to lose interest so 
that they can get back to business as usual. But problem-
oriented policing is not just a fad. It delivers results and is 
here to stay. 

Read More: 

Goldstein, Herman (1979). "Improving Policing: A 
Problem-Oriented Approach." Crime & Delinquency April: 
234-58. 

Goldstein, Herman (1990). Problem-Oriented Policing. 
New York: McGraw Hill. 

Goldstein, Herman (2003). "On Further Developing 
Problem-Oriented Policing. In Problem-Oriented Policing. 
From Innovation to Mainstream." Crime Prevention 
Studies, Volume 15, edited by Johannes Knutsson. 
Monsey, NY: Criminal Justice Press. 


5. Be true to POP

Some police managers attracted to problem-oriented 
policing also apply other strategies, such as 
community policing, "broken windows" policing, 
intelligence-led policing, and CompStat. Depending on 
how these other strategies are implemented, they may or 
may not be compatible with POP. Even when 
implemented in a compatible manner, they are not the 
same as POP. For these reasons it is critical to understand 
how POP differs from these other strategies. 

Problem-oriented policing is a method for analyzing and 
solving crime problems. Community policing, on the other 
hand, represents a broader organizational philosophy. 
Community policing includes problem-solving as 
addressed in problem-oriented policing, but it also 
includes the development of external partnerships with 
community members and groups. Additionally, community 
policing addresses organizational changes that should 
take place in a police agency (such as decentralized 
decision-making, fixed geographic accountability, agency 
wide training, personnel evaluations) designed to support 
collaborative problem-solving, community partnerships, 
and a general proactive orientation to crime and social 
disorder issues. Community policing is therefore more 
focused on police-public interaction than is problem-
oriented policing and represents a broader organizational 
philosophy that incorporates the principles of problem-
oriented policing within it. When done well, community 
policing provides a strong overarching philosophy in 
which to engage in POP, but community policing that fails 
to incorporate the principles of POP within it is unlikely to 
have a substantial impact on reducing crime. 

Problem-oriented policing identifies partners whose help 
is needed in dealing with specific problem. In an ideal 
case, community policing does this as well. If the problem 
is assaults around bus stops, a necessary partner will be 
the local transit authority. If the problem is shoplifting, 
then the cooperation of local businesses is needed. 
Community members often identify problems. Specific 
members of the public (including offenders) can have 
important insights useful for problem analysis. 
Community members can help implement solutions (for 
example, in fitting deadbolts or not giving money to 
beggars). And the success of a problem-solving effort 
might be defined in terms of community reaction. But 
rarely can the community at large help with the 
specialized technical work involved in problem analysis, 
solution development, and evaluation. In addition to 
partnering around specific problems, community policing 
also seeks out partnerships among the community at 
large (and government organizations) in order to increase 
the level of trust and general cooperation with them. In 
this sense, it goes beyond the partnerships described 
under problem-oriented policing. Agencies that adopt the 
broader general philosophy of community policing should 
be careful not to let these partnerships with a different 
purpose (building trust and cooperation) dilute the more 
focused problem-solving partnerships and efforts that the 
community policing philosophy also encourages. 

These distinctions are most easily confused when the 
focus of a problem-oriented project is a deprived 
neighborhood. In this case, the project should proceed by 
identifying the collection of individual problems that 
together make up the greater one (see Step 14). Rather 
than attempting to build a relationship with the 
community at large, a problem-oriented project focuses on 
solving the specific problems of, say, drug houses, 
commercial burglaries, and bar fights. To the extent that 
members of the community become productively involved 
in solving these discrete problems, they may be a rather 
different group of individuals in each case. Broader 
partnerships with the community could be developed in 
order to build trust between police and the community 
and this can make the problem-solving process easier; 
however, even in the absence of widespread community 
support, problems need to be systematically addressed. 

It is also important to understand the difference between 
problem-oriented policing and broken windows policing. 
Under the former, specific solutions to the variety of 
problems confronting the police emerge from careful and 
detailed analysis of the contributory causes of each. By 
contrast, "broken windows" advocates the same general 
solution - policing incivilities and maintaining order whenever 
crime shows signs of becoming out of hand. 
This approach is based on two principles, the first of 
which is that small offenses add up to destroy community 
life. For example, littering one piece of paper is nothing 
terrible, but if everybody does it the neighborhood 
becomes a dump. The second principle of broken windows 
is that small offenses encourage larger ones. For example, 
abandoned and boarded up properties often become the 
scene for drug dealing and can spawn more serious 
crimes. This important insight has led some cities to pay 
much more attention to policing against small offenses. 

All policing requires discretion, and broken windows 
policing requires some very important decisions to be 
made by officers on the street. (This is why it should not 
be confused with "zero tolerance" which is a political 
slogan, impossible for the police to deliver because it 
would soon result in clogged courts and an alienated 


population.) One has to figure out which of the small 
offenses multiply into more crimes and which do not. For 
example, New York City subway system managers learned 
that young men jumping turnstiles to travel free often 
committed robberies within the system. Controlling the 
minor crime helped reduce the major one. But the subway 
managers also learned that those painting graffiti did not 
normally commit more serious crimes. Although their 
efforts to control graffiti were very effective (see Step 41), 
they did not reduce robbery. 

Problem-oriented policing also addresses these less 
serious offenses even if there is no expectation that they 
will lead to worse problems. Vandalism in a public park 
might not increase the chances of robbery, but it does 
destroy public facilities, so it is a problem that needs to be 
addressed. Citizens in a neighborhood may be very 
concerned about speeding, traffic congestion, or noise. As 
long as these meet the criteria for a problem (Step 14) 
they are addressable by POP, even if there is no 
expectation that the neighborhood will deteriorate should 
these go unaddressed. 

Crime analysts are given a central role in intelligence-led 
policing, which puts a premium on the need for sound 
information to guide policing operations. However, 
intelligence-led policing is primarily a methodology for 
producing sound, useable intelligence. It does not guide 
police through the whole process of designing and 
implementing a crime reduction initiative in the way that 
the SARA model is intended to do. Nor does it give a 
central role to crime analysts at every stage in such an 
initiative. This is why problem-oriented policing has a 
great deal more to offer crime analysts and why it expects 
much more of them. 

Finally, problem-oriented policing is not the same as 
CompStat, though they share some common features. 
Both focus police attention, though CompStat as normally 
practiced restricts itself to geographic hot spots while POP 
can be applied to a wider array of crime concentrations. 
Though both use data to drive police action, the variety of 
data and depth of analysis used in POP is greater than 
quick-paced CompStat targeting. CompStat uses law 
enforcement tactics almost exclusively, while POP uses 
these along with a wider variety of responses. CompStat 
may have short-term impacts on geographic hot spots of 
crime that wear off and require more enforcement. A 
problem-oriented approach seeks longer-term solutions. If 
CompStat is used as a "first-aid" response while POP is 
applied to enact a longer-term cure, then the two 
approaches can work well together. 

Read More: 

Wilson, James Q. and George Kelling (1982). "Broken 
Windows." The Atlantic Monthly March: 29-38. 

Table: Differences Between Problem-Oriented Policing and Other Strategies 
Table headers: Focus, Objective, Rationale, Method, First Steps
Row Data:

Problem-oriented policing -
Specific, recurring crime problems
Remove the causes of these problems 
Prevention is more effective than enforcement
Undertake focused action-research (SARA) 
Identify problems requiring attention 

Community policing 
Public-police relations, organizational changes, problem-solving 
Proactive prevention of crime and social disorder and increased 
public confidence in and support of police
Support is critical for police effectiveness. 
Organizational changes are essential to maintain changes, 
problem-solving is a central method to dealing with crime and 
social disorder issues
Build trust by contacts with residents and community meetings, 
enacts organizational changes to support efforts, engages in 
problem-solving
Appoint a community officer for the neighborhood, identify 
problems requiring attention, identify organizational changes 
necessary to support efforts 

Broken windows 
Deteriorating neighborhoods
Halt slide of neighborhood into serious crime 
Nip trouble in the bud 
Policing incivilities/order maintenance 
Identify a deteriorating neighborhood 

Intelligence-led policing 
The process of collecting, analyzing, and disseminating intelligence
Base policing strategies and tactics on sound intelligence
Action only effective when based on sound intelligence
Promote the intelligence cycle of collection, evaluation, collation, 
analysis, and dissemination 
Development of data gathering, processing, and dissemination 

CompStat 
Acute, short term geographic crime patterns 
Reduce crime hot spots 
Fewer hot spots reduce overall crime 
Computerized hot spot identification and intensive patrols and enforcement 
Build crime mapping and geographic accountability 


6. Be very crime specific

Your department will sometimes mount a crackdown 
on a particular crime such as auto crime or burglary, 
and you might be asked to map these offences or 
provide other data to support the operation. But these 
categories are too broad for problem-oriented policing. 
They include too many different kinds of crimes, all of 
which need to be separately analyzed. For example, "auto 
crime" could include: 

 Stealing hubcaps for resale or badges for collections. 
 Breaking into cars to steal items left inside. 
 Breaking into cars and stealing radios and other fittings. 
 Joyriding by juveniles. 
 Taking a car for temporary transport. 
 Stealing a car for use in another crime. 
 Stealing and keeping a car. 
 Stealing cars for "chopping" and sale of the parts. 
 Stealing cars for resale. 
 Stealing cars for export overseas. 
 Carjacking. 

You can see these crimes are committed for a variety of 
motives, by different offenders, with varying degrees of 
organization, knowledge and skills. Stealing hubcaps is 
the least difficult and daring and is committed by juvenile 
wanabees. Joyriding requires more courage and some 
basic knowledge about starting and driving cars. Stealing 
cars for export is a much more complicated crime 
requiring high levels of organization, with many more 
stages and people involved. The offenders are as likely to 
be dishonest businessmen as career criminals. More 
ruthless, hardened criminals commit carjacking. 

These differences between crimes explain why the 
solutions to each cannot be the same. Joyriding can be 
reduced by better built-in security, which explains why 
immobilizers are now bringing down overall levels of car 
theft. However, immobilizers cannot prevent carjacking 
because victims can be forced to hand over the keys if 
these are not already in the ignition. In fact, some 
commentators believe that carjacking has increased 
because newer cars with ignition immobilizers are difficult 
to steal in the usual way. Immobilizers can also be 
overcome by those with sufficient technical skill and they 
may do little to reduce theft of cars for export. The 
solution to this problem may lie in better port and border 
controls and documents that are harder to forge. 

Breaking down a larger problem of crime into smaller 
categories is merely the first step in tightening the focus 
of a POP project. For example, a recent POP project in 
Charlotte, NC, originally focused on downtown thefts from 
cars, became progressively more specific as the analysis of 
the problem unfolded. First, it became clear that the 
problem was concentrated in the car parks. Only 17% 
involved cars parked in residences or on the streets. Then 
it was found after counting parking spaces that cars in 
surface lots were six times more at risk than those in 
parking garages, which were generally more secure (see 
Step 27). This meant the project could focus on improving 
security in the surface lots through better lighting and 
fencing, and more supervision by attendants. This would 
be much easier than trying to reduce the already low 
levels of theft in the parking garages. Tightening the focus 
of a POP project in this way increases the probability of 
success and uses resources effectively. 

There are few rules for determining precisely the level of 
specificity needed for a successful POP project. Tightening 
the focus too much could result in too few crimes being 
addressed to justify the expenditure of resources, though 
this depends on the nature and seriousness of the crimes. 
If only a few hubcaps are being stolen, then this problem 
would not merit a full-blown POP project. On the other 
hand, a POP project to reduce corner store robberies 
could be worth undertaking, even if only a few such 
robberies occur each year, because these can escalate into 
worse crimes such as murder, and because they increase 
public fear. 

Quote: "Because so much effort has been concentrated on 
crude groupings of crime types, such as burglary, 
robbery or auto theft, it has been virtually impossible to 
find truly common facts about the conditions which lead 
to each of these groups of crimes. This implies that we 
have to be very patient and try to solve the problems of 
crime gradually and progressively, piece by piece." 
Source: Poyner, Barry (1986). "A Model for Action". 
Situational Crime Prevention, edited by Gloria Laycock 
and Kevin Heal. London: Her Majesty's Stationery Office. 


Being More Specific about Residential Burglary 

Barry Poyner and Barry Webb have argued that preventing residential burglaries targeted on electronic goods 
requires quite different measures from those to prevent burglaries targeted on cash or jewelry. This is because they 
found many differences between these two sorts of burglaries in the city they studied. When the targets were cash or 
jewelry, burglaries occurred mostly in older homes near to the downtown area and were apparently committed by 
offenders on foot. When the targets were electronic goods such as TVs and VCRs, the burglaries generally took place 
in newer, more distant suburbs and were committed by offenders with cars. The cars were needed to transport the 
stolen goods and had to be parked near to the house, but not so close as to attract attention. The layout of housing 
in the newer suburbs allowed these conditions to be met, and Poyner and Webb's preventive suggestions consisted 
principally of means to counter the lack of natural surveillance of parking places and roadways. Their suggestions to 
prevent inner city burglaries focused more on improving security and surveillance at the point of entry. 

Source: Poyner, Barry and Barry Webb (1991). Crime Free Housing. Oxford: Butterworth-Architecture. 

Some serious crimes, such as school shootings, are so rare 
that they cannot be properly addressed at the local level 
by problem-oriented policing. This is because the 
methodology depends upon a certain level of repetition to 
permit underlying causes to be identified. For these kinds 
of crimes, police forces must ensure that routine security 
measures are in place and that they have a well-worked 
out plan for responding to incidents. 

While one should avoid beginning with a solution, some 
solutions for specific crimes are so promising that they 
might help define the focus of a POP project. To return to 
the example of robbery at corner stores, there is good 
research showing that having at least two members of 
staff on duty can reduce late night robberies of these 
stores. You could therefore take a look at how many 
corner store robberies occur late at night in your area. If 
there were enough of them, you might persuade your 
department to mount a POP project focused on these late 
night robberies simply because you know that an effective 
solution exists. 

Finally, as you learn more about a problem in the analysis 
stage, you might decide that it is so similar to a related 
problem that it is worth addressing the two together. For 
instance, when working on a problem of assaults on taxi 
drivers, you might discover that many of these are related 
to robbery attempts and that it would be more 
economical to focus your project on both robberies and 
assaults. In this way you may identify a package of 
measures that would reduce the two problems together. 

Separate Problems, Common Solutions

Specific problems in a dilapidated neighborhood or apartment complex should always be separately analyzed, but, for cost- effectiveness 
reasons, solutions ought to be considered together. In the hypothetical example below, the last identified solution, a gatekeeper and 
closed circuit television (CCTV) system, is the most costly of all those listed. But it is also predicted to be the most effective solution for 
each problem. It might therefore be chosen as a solution to all three problems when costs might have ruled out its selection for just one 
of the problems. 

IDENTIFIED SOLUTIONS 
(from least costly to most) 
Trim bushes to improve surveillance ($) 
Block watch scheme ($) 
Alarms for elevators ($$) 
Electronic access to parking lot ($$) 
Installation of entry phone ($$$) 
Security patrol ($$$$) 
Window locks and strengthened doors for apartments ($$$$) 
Gatekeeper and complex-wide CCTV cameras ($$$$$) 
 
VANDALISM TO 
ELEVATORS 
*** 
**** 
** 
* 
**** 
THEFTS 
OF/FROM CARS 
** 
* 
**** 
** 
**** 
BURGLARIES OF 
APARTMENTS 
** 
* 
**** 
** 
**** 
$ Predicted costs * Predicted effectiveness 


7. Be guided by SARA  but not led astray!

Within problem-oriented policing, the police are 
required to: (1) carefully define specific problems 
(see Step 14 for the definition of "problem"); (2) 
conduct in-depth analyses to understand their causes; (3) 
undertake broad searches for solutions to remove these 
causes and bring about lasting reductions in problems; 
and (4) evaluate how successful these activities have 
been. This is a form of action research, a well-established 
social science method in which researchers work 
alongside practitioners, helping to formulate and refine 
interventions until success is achieved. This can be 
contrasted with the usual role of researchers, in which 
they work apart from the practitioners, collect background 
information about problems, and conduct independent 
evaluations. In action research, however, the researcher is 
an integral member of the problem-solving team. This is 
the role of the crime analyst. Your analyses must inform 
and guide action at every stage. 

You will find that SARA will help you and your team keep 
on track. This is the acronym formulated by John Eck and 
Bill Spelman to refer to the four problem-solving stages of 
Scanning, Analysis, Response and Assessment. This 
process is very similar to many other analytical processes, 
including the standard crime analysis process of 
collection, collation, analysis, dissemination, and feedback. 
By dividing the overall project into separate stages, SARA 
helps to ensure that the necessary steps are undertaken in 
proper sequence - for example, that solutions are not 
adopted before an analysis of the problem has been 
undertaken. This is a useful check on the natural tendency 
to jump straight to a final response, while skimping on 
definition of the problem and analysis and forgetting to 
assess their impact on the problem. 

Problem-solving projects can be complex. In action 
research, the team is expected to persist until success is 
achieved, refining and improving an intervention in the 
light of what is learned from earlier experiences. The 
process is not necessarily completed once the assessment 
has been made. If the problem persists, or has changed its 
form, the team may have to start over. This is represented 
in the figure where the outer arrows describe the 
feedback between assessment and scanning. 

However, the four problem-solving stages do not always 
follow one another in a strictly linear fashion. In fact, 
projects rarely follow a linear path from the initial 
scanning and analysis stages through the stages of 
response and assessment. Rather, the process often has 
loops, so that an unfolding analysis can result in 
refocusing of the project, and questions about possible 
responses can lead to the need for fresh analyses. The 
longer and more complicated the project, the more loops 
of this kind are likely to occur. The set of smaller inner 
arrows in the figure illustrate this dynamic process. For 
example, one might jump from scanning to the 
implementation of a short-term emergency response to 
stabilize the problem while further analysis is undertaken. 
An assessment of the short-term response could add to 
the analysis and contribute to the formulation of a new 
response, which is then assessed. This might lead back to 
scanning as new information forces a revision of the 
problem definition or the discovery of new problems. The 
important point is that analysis and evaluation are 
meaningfully incorporated into the sequence of events 
and one does not simply jump from scanning to response 
and declare victory. 

IMAGE OF THE SARA PROBLEM-SOLVING PROCESS 
SCANNING ANALYSIS ASSESSMENT RESPONSE 



One of us (Clarke) recently worked with Herman Goldstein 
on a project to reduce thefts of appliances from houses 
under construction in Charlotte, North Carolina. The 
housing developments were often in fairly isolated rural 
areas and were impossible to patrol effectively. They were 
difficult to secure because builders wanted to encourage 
prospective buyers to tour the sites in the evenings and 
on weekends. Because few offenders were ever caught, 
we knew little about them or how they disposed of the 
appliances. We considered a wide range of possible 
solutions including storing appliances in secure containers 
on site and the use of portable alarms and closed-circuit 
television cameras. Then we hit on a solution being used 
by some small builders - to delay installation of the 
appliances until the day that the buyer took possession. 

Many builders were hostile at first to the idea. Sales staff 
believed that having the appliances installed made a 
home more saleable, and that the absence of appliances, 
if attributed to theft, might alarm purchasers about the 
area they were moving into. Site supervisors felt that 
delivering and installing appliances as houses were 
occupied would be more difficult than batch delivery and 
installation. Some erroneously believed that building 
inspectors would not certify the houses as suitable for 
occupancy unless appliances were in place. Others 
wrongly believed that this was a mortgage requirement. 
Finally, individual installation would mean that builders 
could no longer arrange for building inspectors to visit a 
site and issue certificates of occupancy wholesale. 

Because the solution had so many advantages, we 
decided to return to the analysis stage to find answers to 
the builders' objections. Ultimately, this information was 
useful in persuading builders to adopt the solution and 
thus reduce the number of appliance thefts. 

This shows how problem-oriented policing is a process in 
which the gradual acquisition of data and information 
informs the project, leading to more questions, to 
redefinition, and even to changes in focus as it moves 
along. As soon as a promising response is identified, its 
costs and benefits need to be analyzed in depth. The 
alternative of comprehensively exploring all available 
response options runs the risk that the project will lose 
momentum and the support of those involved. 

SARA and the "5 I's" 
Paul Ekblom of the British Home Office has recently 
proposed a development of SARA consisting of: 
Intelligence, Intervention, Implementation, Involvement, 
and Impact and process evaluation. The "5 I's" are 
supported by a wealth of practical concepts and tools. 

A summary can be found at: 
www.crimereduction.gov.ukwww.jdi.ucl.ac.uk 

Read More: 

Clarke, Ronald and Herman Goldstein (2002). "Reducing 
Theft at Construction Sites: Lessons from a Problem-
Oriented Project." Crime Prevention Studies, volume 13, 
edited by Nick Tilley. Monsey, New York: Criminal Justice 
Press. (accessible at: www.popcenter.org/library.htm) 

Eck, John (2003). "Why Don't Problems Get Solved?" 
Community Policing: Can It Work?, edited by Wesley 
Skogan. Belmont, California: Wadsworth. 


8. Use the problem analysis triangle

Most criminological theories focus on what makes 
people "criminal". They find causes in distant 
factors, such as child-rearing practices, genetic 
makeup, and psychological or social processes. These 
theories are very difficult to test; are of varying and 
unknown scientific validity; and yield ambiguous policy 
implications that are mostly beyond the reach of police 
practice. But you will find that the theories and concepts 
of environmental criminology (and of the new discipline of 
crime science) are very helpful in everyday police work. 
This is because they deal with the immediate situational 
causes of crime events, including temptations and 
opportunities and inadequate protection of targets. You 
will be a stronger member of the problem-oriented team 
if you are familiar with these concepts. 

The problem analysis triangle (also known as the crime 
triangle) comes from one of the main theories of 
environmental criminology - routine activity theory. This 
theory, originally formulated by Lawrence Cohen and 
Marcus Felson, states that predatory crime occurs when a 
likely offender and suitable target come together in time 
and place, without a capable guardian present. It takes 
the existence of a likely offender for granted since normal 
human greed and selfishness are sufficient explanations 
of most criminal motivation. It makes no distinction 
between a human victim and an inanimate target since 
both can meet the offender's purpose. And it defines a 
capable guardian in terms of both human actors and 
security devices. This formulation led to the original 
problem analysis triangle with the three sides representing 
the offender, the target, and the location, or place (see 
inner triangle of the figure). 

By directing attention to the three major components of 
any problem, the inner triangle helps to ensure that your 
analysis covers all three. Police are used to thinking about 
a problem in terms of the offenders involved - indeed, the 
usual focus is almost exclusively on how to identify and 
arrest them. But POP requires that you explore a broader 
range of factors and this requires information about the 
victims and the places involved. 

The latest formulation of the problem analysis triangle 
adds an outer triangle of "controllers" for each of the 
three original elements (see figure): 

 For the target/victim, this is the capable guardian of the 
original formulation of routine activity theory - usually 
people protecting themselves, their own belongings or 
those of family members, friends, and co-workers. 
Guardians also include public police and private security. 

 For the offender, this is the handler, someone who 
knows the offender well and who is in a position to 
exert some control over his or her actions. Handlers 
include parents, siblings, teachers, friends and spouses. 
Probation and parole authorities often augment or 
substitute for normal handlers. 

 For the place, the controller is the manager, the owner 
or designee who has some responsibility for controlling 
behavior in the specific location such as a bus driver or 
teacher in a school, bar owners in drinking 
establishments, landlords in rental housing, or flight 
attendants on commercial airliners. 

Image of Problem Analysis Triangle 


The problem analysis triangle is the basis for another 
useful analytic tool - a classification of the three main 
kinds of problems that confront police and a theory about 
how these problems arise. John Eck and William Spelman 
have proposed classifying such problems as "wolf," 
"duck" and "den" problems: 

1. Repeat offending problems involve offenders attacking 
different targets at different places. These are ravenous 
WOLF problems. An armed robber who attacks a series 
of different banks is an example of a pure wolf problem. 
Wolf problems occur when offenders are able to locate 
temporarily vulnerable targets and places. The 
controllers for these targets and places may act to 
prevent future attacks, but the offenders move on to 
other targets and places. It is the lack of control by 
handlers that facilitates wolf problems. 

2. Repeat victimization problems involve victims 
repeatedly attacked by different offenders. These are 
sitting DUCK problems. Taxi drivers repeatedly robbed in 
different locations by different people is an example of a 
pure duck problem. Duck problems occur when victims 
continually interact with potential offenders at different 
places, but the victims do not increase their 
precautionary measures and their guardians are either 
absent or ineffective. 

3. Repeat location problems involve different offenders 
and different targets interacting at the same place. 
These are DEN of iniquity problems. A drinking 
establishment that has many fights, but always among 
different people, is an example of a pure den problem. 
Den problems occur when new potential offenders and 
new potential targets encounter each other in a place 
where management is ineffective. The setting continues 
to facilitate the problem events. 

Note that pure wolf, duck, and den problems are rare. 
Most problems involve a mixture. The question is, which is 
most dominant in a given problem: wolves, ducks, 
or dens? 

When crime is occurring, all inner elements of the triangle 
must be present and all outer elements weak or absent. 
If potential offenders are constantly present, for example, 
but crimes occur only when guardians are absent, then 
rescheduling guardians might be a useful solution. Ask 
yourself, "What does the problem analysis triangle look 
like before, during, and after crimes?" 

Understanding how problems are created by opportunities 
will help you think about what might be done to: prevent 
offenders from reoffending by making better use of 
handlers; help victims reduce their probabilities of being 
targets; and to change places where problems occur, be 
these schools, taverns, or parking lots. In short, right from 
the beginning, it helps you to focus data collection on 
those six aspects most likely to lead to practical solutions. 

What is Crime Science? 

Traditional criminology seeks to improve understanding of the psychological and social forces that cause people to 
become criminals in the hope of finding ways to change these causes. Crime science takes a radically different 
approach. It focuses not on the reasons why criminals are born or made, but on the act of committing crime. It seeks 
ways to reduce the opportunities and temptations for crime and increase the risks of detection. In doing so, it seeks 
contributions from a wide range of disciplines, including psychology, geography, medicine, town planning, and 
architecture. Crime science explicitly seeks to be judged by the extent to which it helps to reduce crime on our 
streets, and in our homes and businesses. 

Source: Jill Dando Institute for Crime Science. (2004). www.jdi.ucl.ac.uk 


9. Know that opportunity makes the thief

For environmental criminologists, "opportunity makes 
the thief" is more than just a popular saying; it is the 
cornerstone of their approach. They believe that if 
opportunity increases so will crime. To see if you agree, 
consider the scenario suggested by Gloria Laycock and 
Nick Tilley of the Jill Dando Institute of Crime Science: 

Suppose all situational controls were to be 
abandoned: no locks, no custom controls, 
cash left for parking in an open pot for occasional 
collection, no library check-outs, no baggage 
screening at airports, no ticket checks at train 
stations, no traffic lights, etc., would there be no 
change in the volume of crime and disorder? 

If you answer that of course crime and disorder would 
increase, then you, too, think opportunity is a cause of 
crime. Incredibly, most criminologists would not agree. 
They believe that opportunity can only determine when 
and where crime occurs, not whether it occurs. In their 
view, whether crime occurs is wholly dependent on 
offenders' propensities and these propensities collectively 
determine the volume of crime in society. 

In fact, crime levels are as much determined by the 
opportunities afforded by the physical and social 
arrangements of society as by the attitudes and 
dispositions of the population. This is difficult to prove 
without conducting experiments, but it would be unethical 
to create new opportunities for burglary or robbery and 
wait to see what happens. However, experiments have 
been undertaken with minor transgressions. In the 1920s, 
researchers gave children the opportunity to cheat on 
tests, to lie about cheating, and to steal coins from 
puzzles used. Other researchers have scattered stamped 
and addressed letters in the streets, some containing 
money, to see if these were mailed. In a third group of lab 
experiments, subjects were instructed to "punish" others 
for disobeying test instructions by delivering severe 
electric shocks through the test apparatus. (In fact, no 
shocks were actually delivered). 

The results of these experiments support the causal role of 
opportunity. Most of the subjects, even those who 
generally resisted temptation, took some opportunities to 
behave dishonestly or aggressively - opportunities they 
would not have encountered but for their participation in 
the studies. But you cannot generalize from these minor 
transgressions to crimes of robbery or car theft. We, 
therefore, must turn to some other sources of evidence 
about the importance of opportunity in causing crime. 

Suicide and opportunity. Suicide is not a crime, but 
like much crime is generally thought to be deeply 
motivated. However, there is clear evidence from the U.K. 
that opportunity plays an important part in suicide. During 
the 1950s, about half the people who killed themselves in 
the U.K. used domestic gas, which contained lethal 
amounts of carbon monoxide (CO). This was known as 
"putting your head in the gas oven." In the 1960s, gas 
began to be made from oil instead of coal. The new gas 
had less CO and the number of gas suicides began to 
decline. By 1968, only about 20 percent of suicides 
involved gas. This is when a second change began: 
manufactured gas was replaced by natural gas from the 
North Sea. Natural gas contains no CO and is almost 
impossible to use for suicide. By the mid-1970s, less than 
1 percent of suicides in the U.K. used this method. 

What is deeply surprising is that suicides did not displace 
wholesale to other methods. The table shows that 
between 1958 and 1976 suicides dropped by nearly 30 
percent from 5,298 to 3,816. (This was during an 
economic decline when suicide could have been expected 
to increase and, indeed, was increasing in other European 
countries.) People did not turn to other methods because 
these all had drawbacks. Overdoses are much less lethal 
than carbon monoxide. Hanging requires more knowledge 
as well as courage. Not everyone has access to guns, 
which can result in disfigurement instead of death. On the 
other hand, domestic gas was readily available in most 
homes. It was highly lethal and using it was bloodless and 
painless. It is not surprising it was the preferred method 
for so long and that when the opportunity to use it was 
removed, the number of suicides declined. 


Table: Suicides in England and Wales 1958-1977
Table Headers: Year, Total Suicides, Suicides by Domestic Gas, Percent of Total
 
1958, 5298, 2637, 49.8
1960, 5112, 2499, 48.9 
1962, 5588, 2469, 44.2 
1964, 5566, 2088, 37.5 
1966, 4994, 1593, 31.9 
1968, 4584, 988, 21.6 
1970, 3940, 511, 13.0 
1972, 3770, 197, 5.2 
1974, 3899, 50, 1.3 
1976, 3816, 14, 0.4  
 
Source: Mortality Statistics, England and Wales: Causes. London: 
Her Majesty's Stationery Office, Annual 

Murder and opportunity. Opportunity also plays an 
important causal role in murder, as shown by a 
comparison made some years ago of homicide rates in the 
United States and the U.K. For 1980-84, the period 
covered by the study, the overall homicide rate in this 
country was 8.5 times greater than in England and Wales. 
The gun homicide and handgun homicide rates were, 
respectively, 63 times and 75 times as great. In the whole 
of England and Wales in this period (with about 50 
million people), only 57 handgun murders occurred. In the 
United States, with a population of about 230 million 
(less than five times greater) a total of 46,553 people 
were murdered with a handgun. 

These findings tended to be dismissed because the overall 
crime rate in the U.S. was generally higher than it was in 
England and Wales during that period. However, in the 
past 15 years the overall crime rates of the two countries 
have converged so that there is now little difference 
between them, with the glaring exception of homicide. 
There is still a much higher rate of murder in this country 
because far more people here own guns, especially 
handguns, than in the U.K. Even the police in the U.K. do 
not routinely carry guns! So, when people fight here, 
someone is much more likely to get shot than in the U.K. 
Similar, but not such striking findings, emerge from 
comparing murder rates in the U.S. and Canada (see box). 
Taken together, these comparisons show that gun 
availability (an opportunity variable) plays an important 
causal role in murder. 

Understanding the arguments in this section, and 
accepting that opportunity causes crime, does not mean 
you must deny the importance of other causes, such as 
inherited personalities, broken homes, and inconsistent 
discipline. But there is little you can do to change people's 
personalities or the divorce rate or poor parenting. 
However, you can alter the criminogenic situations in 
which they find themselves. Understanding that 
opportunity makes the thief will help direct your attention 
to practical means of preventing crime, and help you 
defend them from criticism. 

Guns and Homicide in the 
United States and Canada 
A classic study compared the rate of homicides and 
assaults in Seattle (U.S.A.) and Vancouver (Canada) from 
1980-1986 to determine the effect of handgun 
availability on the crime rate. Although similar to Seattle 
in many ways, Vancouver has a more restrictive 
approach to handgun possession. The study found that 
wider availability of handguns increases the rate of 
homicide. The key findings were: 
1. The two cities differed little in their rate of assaults. 
2. The murder risk was significantly higher in Seattle 
than in Vancouver, mainly due to a five times 
greater risk of being murdered with a handgun in 
Seattle. 
3. Rates of non-gun homicides differed little between 
the two cities. 

Source: Sloan, John and colleagues (1988). "Handgun 
Regulations, Crime, Assaults, and Homicide." The New 
England Journal of Medicine, 319: 1256-1262. 

Read More: 
Felson, Marcus and Ronald Clarke (1998). Opportunity 
Makes the Thief. Police Research Series, Paper 98. 
London: Home Office 


10. Put yourself in the offender's shoes

Whenever you analyze a crime problem or think 
about solutions, try to see the crime from the 
offender's perspective. Try to understand why 
they commit the crime - not the distant social or 
psychological causes, but the benefits they are seeking. A 
radical critique of criminology pointed out 30 years ago 
that is not their genes that propel bank robbers through 
the doors of the bank: they rob banks because they want 
to get rich. 

In many cases of theft and robbery the benefits are 
obvious, but they may not be clear for gang violence or 
so-called "senseless" vandalism and graffiti. In fact, 
graffiti can mark the territory of a juvenile gang, can 
indicate where to purchase drugs, or can simply be a way 
to show off. Knowing which of these reasons is dominant 
helps to define the focus of a problem-solving project and 
unravel the contributory factors. It can also help the 
project team identify solutions. Thus, the New York City 
subway authorities succeeded in eradicating graffiti only 
when they understood the motivation of the "taggers," 
which was to see their handiwork on display as the trains 
traveled around the system (see Step 41). 

Learning how offenders commit crimes is as important as 
learning why they commit them. You will find rational 
choice theory helpful in thinking about these questions. 
The name is misleading because the theory does not 
assume that offenders plan their crimes carefully; it 
assumes only that they are seeking to benefit themselves 
by their crimes, which is rational enough. The theory does 
not even assume that offenders succeed in obtaining the 
benefits they seek. This is because they rarely have all the 
information they need, they do not devote enough time to 
planning their actions, they take risks, and they make 
mistakes. This is how we all behave in everyday decision-
making and is what theorists call limited or bounded 
rationality. 

Offenders must often decide quickly how to accomplish 
their goals and how to get away without being caught. 
Interviewing offenders will help you understand how they 
make these decisions. (The COPS Guide on interviewing 
offenders will help you think about the legal and technical 
difficulties of conducting these interviews. See Read 
More.) Surprisingly, it is usually not difficult to get 
offenders to talk, especially if you confine yourself to the 
general nature of the problem you are trying to solve, and 
avoid specific questions about crimes they have 
committed. Offenders are no exception to the rule that we 
enjoy talking about ourselves and about the work we do. 
On the other hand, always retain some skepticism as 
people who habitually break the law may also habitually 
exaggerate and lie. 

Martin Gill of Leicester University in England tells a story 
of interviewing an experienced offender in prison. When 
dealing with the crime that had led to his arrest, Gill 
asked: "Did you think you'd get caught?" The prisoner 
leaned back in his chair and gave him a long look 
before saying: "I never expected to hear someone from 
a university ask such a stupid question. Do you think I'd 
have done it, if I thought I'd get caught?" 

If you cannot interview offenders, try to imagine the 
course of a crime (see Step 35). What must be done at 
each stage? How are targets selected? How can victims 
be subdued or tricked? The police escaped? The goods 
disposed of? Even if you cannot answer all these 
questions about modus operandi, your attempt to enter 
the offender's mind can help you think about responses. 
This is not an invitation to try your hand at 
psychoanalysis. Instead of delving into the offender's 
unconscious you should try to understand the tangible 
benefits the offender is seeking and how he must manage 
the commission of crime without too much effort or risk. 
This is what Paul Ekblom of the Home Office Research 
Department means when he advises problem solvers to 
"think thief." 

Paul Ekblom interviewed thieves on the London 
Underground (subway system) who told him that they 
would stand near signs warning that "pickpockets" 
were operating. On noticing the signs, passengers 
would reassuringly pat whichever pockets contained 
their wallets, which was a considerable help to the 
thieves. 

Another alternative to interviewing your own group of 
offenders is to search the literature for reports of 
interviews with similar groups of offenders. Environmental 
criminologists have greatly expanded our knowledge 
about the methods that criminals use by interviewing car 
thieves, muggers, shoplifters, and residential and 
commercial burglars. The offenders may not be quite the 
same group as your own, but carefully looking at the 
results of these interview studies can suggest hypotheses 
that you might explore in regard to your own problem. 

Read More: 

Decker, Scott (2004). Using Offender Interviews to Inform 
Police Problem-Solving Guide No. 3. Problem-Oriented 
Guides for Police, Problem Solving Tool Series. 
Washington, D.C.: Office of Community Oriented Policing 
Services, U.S. Department of Justice. (Accessible at 
www.popcenter.org and www.cops.usdoj.gov). 

Motives 
"You are sitting there alone and you feeling light in your pocket, your rent is due, light and gas bill, you got these bill 
collectors sending you letters all the time, and you say, 'I wish I had some money. I need some money.' Those are the 
haints. [You haint got this and you haint got that.] Your mind starts tripping cause you ain't got no money and the 
wolves are at the door... [After my last stickup] I gave my landlord some money and sent a little money off to the 
electric company, a little bit off to the gas company. I still had like twenty or thirty dollars in my pocket. I got me 
some beer, some cigarettes, and [spent] some on a stone [of crack cocaine]; enjoy myself for a minute" (pp. 43-44). 

Advantages of robbery 
"Robbery is the quickest money. Robbery is the most money you gonna get fast... Burglary, you gonna have to sell 
the merchandise and get the money. Drugs, you gonna have to deal with too many people, [a] bunch of people. You 
gonna sell a fifty-dollar or hundred dollar bag to him, a fifty-dollar or hundred-dollar bag to him, it takes too long. 
But if you find where the cash money is and just go take it, you get it all in one wad" (pp. 51-52). 

Choosing the victim 
"See, I know the places to go [to locate good robbery targets]. Usually I go to all the places where dope men hang 
out... but I [also have] done some people coming out of those instant tellers" (p. 78). 
"That's all I done robbed is drug dealers ... they not gonna call the police. What they gonna tell the police? He 
robbed me for my dope? They is the easiest bait to me. I don't want to harm no innocent people, I just deal basically 
with drug dealers" (p. 64). 

Violence 
"Well, if [the victim] hesitates like that, undecided, you get a little aggressive and you push them ...I might take [the] 
pistol and crack their head with it. 'Come on with that money and quit bullcrapping or else you gonna get into some 
real trouble!' Normally when they see you mean that kind of business they ... come on out with it" (p. 109). 
Armed Robbers Talking 
Source: Wright, Richard and Scott Decker (1997). Armed Robbers in Action. Boston: Northeastern University Press. 


11. Expect offenders to react

Offenders make choices based on their perceptions 
of opportunities. Understanding how offenders see 
things is important to preventing crime because 
almost all crime prevention involves changing offenders' 
perceptions of crime opportunities. Some prevention 
programs work directly on offenders' perceptions, as when 
police inform offenders that they are being closely 
watched. But most prevention schemes work through one 
or more intermediate steps, as in property marking 
schemes, for example, where residents apply window 
stickers showing participation. Changes in the 
environment change offender perceptions. These 
perceptions influence offenders' behaviors that, in turn, 
alter crime patterns. 

In many cases, the preventive measures deter offenders 
from further criminal activity. They can also have the 
positive unintended effects of: (1) reducing crime beyond 
the focus of the measures, which is known as diffusion of 
benefits (see Steps 13 and 47); and (2) reducing crime 
before they have actually been implemented, known as 
anticipatory benefits (Step 52). However, preventive 
measures do not always achieve the desired effects, 
sometimes because offenders are quite unaware of the 
interventions in place. For example, offenders may 
continue to offend in the face of covert enforcement 
because they might not perceive that their risks of being 
caught have increased. In other cases, offenders may 
adjust negatively to the preventive measures. These 
negative adjustments include displacement and long-term 
adaptation. 

 Displacement occurs when offenders change their 
behavior to thwart preventive actions. Displacement is 
the opposite of diffusion of benefits. Displacement is a 
possible threat, but it is far from inevitable. Reviews 
show that many situational prevention programs show 
little or no evidence of displacement, and when 
displacement is found, it seldom fully offsets the 
prevention benefits (Step 12). 

 Adaptation refers to a longer term process whereby 
the offender population as a whole discovers new crime 
vulnerabilities after preventive measures have been in 
place for a while. Paul Ekblom, Ken Pease, and other 
researchers often use the analogy of an arms race 
between preventers and offenders when discussing this 
process. So, in time, we can expect many crimes that 

have been reduced by preventive measures to reappear 
as criminals discover new ways to commit them. 
Adaptation may occur as the original offenders slowly 
discover new methods, or it may occur as new offenders 
take advantage of changing opportunities. 

A good example of adaptation is credit card fraud (see 
the Box). Another more recent example of adaptation 
involves bike locks. Bike thieves discovered that they 
could defeat a widely used and effective lock by using a 
common and cheap ballpoint pen. But not all preventive 
measures are so vulnerable to criminal ingenuity. For 
example, Neal Shover has argued that technology has 
brought a lasting respite from safecracking, which is now 
very rare though it was once quite common. 

In some circumstances preventive actions may stimulate 
defiance. This occurs when offenders challenge the 
legitimacy of prevention efforts and commit more crimes 
rather than fewer. Police are legitimately concerned, for 
example, that premature displays of force can sometimes 
stimulate crowds to engage in riotous behavior, so police 
often refrain from dressing in full riot gear until there is 
strong evidence that serious misbehavior is likely. There is 
some research evidence that defiance is more likely when 
the police are perceived to be unfair and heavy handed, 
and that people are more law abiding when police treat 
them fairly, even if the outcome is not what people desire. 
In general, defiance is not a well-documented 
phenomenon, but it cannot be ruled out as a possibility, 
particularly when police use enforcement as the principal 
prevention tool. 

Read More: 

Ekblom, Paul (1997). "Gearing up Against Crime: a 
Dynamic Framework to Help Designers Keep up with the 
Adaptive Criminal in a Changing World." International 
Journal of Risk, Security and Crime Prevention, 2: 249-
265.
(Accessible at www.homeoffice.gov.uk/rds/pdfs/risk.pdf)


Offender Adaptation and Credit Card Fraud 

Michael Levi and his colleagues have described how a partnership between the police, the British Home Office 
(similar to the U.S. Department of Justice), and the credit card issuers led to successful action in the mid-1990s to 
reduce credit card frauds. The measures introduced included new lower limits for retailers for seeking authorization 
of transactions and more secure methods of delivering new credit cards to consumers via the mail. As the figure 
shows, there was a resulting marked reduction in fraud losses (total, lost & stolen, and mail non-receipt). In recent 
years, however, credit card losses have begun to climb again. This is due principally to a growth in losses resulting 
from "card not present frauds" (due to the rapid expansion of Internet sales) and in counterfeiting of cards (said to 
be the work of organized gangs in East Asia). 

Line graph showing Credit Card Losses, UK from 1991 to 2000
 

12. Don't be discouraged by the displacement doomsters

Problem-oriented policing often tries to reduce 
opportunities for crime. For example, window locks 
may be fitted to prevent burglary in an apartment 
complex, or closed circuit television cameras installed to 
prevent thefts in parking lots. These ways of reducing 
opportunities for crime often meet the same objection: all 
they do is move crime around, not prevent it. This theory 
of displacement sees crime as being shifted around in five 
main ways: 

1. Crime is moved from one place to another 
(geographical). 

2. Crime is moved from one time to another (temporal). 

3. Crime is directed away from one target to another 
(target). 

4. One method of committing crime replaces another 
(tactical). 

5. One kind of crime is substituted for another (crime 
type). 

In each case, the theory assumes that offenders are 
compelled to commit crime, whatever impediments they 
face. The basis for the assumption is either that the 
propensity to commit crime builds up and must be 
discharged in the same way that sexual release is sought, 
or that "professional" criminals or drug addicts must 
obtain a certain income from crime to maintain their 
lifestyles. There is no evidence that offenders must satiate 
some deep physiological appetite to commit crimes. In 
fact, there is plenty of evidence that people make choices 
about whether, where, and when to offend. Whatever its 
basis, the displacement assumption neglects the important 
role of temptation and opportunity in crime (Step 9). 

Even in the case of more committed offenders, the 
displacement theory fails to give enough importance to 
opportunity. Thus, research on drug addicts has shown 
that they adapt to variations in the supply of drugs. Nor is 
there any simple progression in drug use. Rather, addicts 
might be forced to use smaller amounts or less agreeable 
drugs because the supply of drugs has been cut. 

As for professional criminals like bank robbers, there is no 
reason to assume that they must obtain a fixed amount of 
money from crime. They would surely commit fewer 
robberies if these became difficult and risky, just as they 
would commit more robberies if these became easy. Bank 
robbers, like everyone else, may sometimes have to adjust 
to reduced circumstances and be content with lower 
levels of income. 

This does not mean that we can ignore displacement. 
Indeed, rational choice theory predicts that offenders will 
displace when the benefits for doing so outweigh the 
costs. For example, in the early 1990s the New York City 
Police deployed its Tactical Narcotics Teams to several high 
drug-dealing neighborhoods. Dealers responded by 
shifting their sales locations from curbside to inside the 
foyers of apartment buildings. But numerous other studies 
have found that displacement did not occur at all, or only 
to a limited extent. For example: 

 Intensive gun patrols reduced firearms crimes in a 
Kansas City, Missouri high gun-crime neighborhood 
without displacing these or other crimes to 
nearby communities. 

 New identification procedures greatly reduced check 
frauds in Sweden, with no evidence of displacement to a 
range of "conceivable" alternative crimes. 

 Extensive target hardening undertaken in banks in 
Australia lowered robbery rates, but there was no sign 
that corner stores, gas stations, betting shops, motels, or 
people in the street began to experience more robberies. 

 Burglary was not displaced to nearby apartment 
complexes when a problem-solving approach drove 
down burglary in a high-crime apartment complex in 
Newport News, Virginia. 

 When streets were closed in the London neighborhood 
of Finsbury Park and policing was intensified, there was 
little evidence that prostitutes simply moved to other 
nearby locations. According to the researchers, many of 
the women working the streets in Finsbury Park were 
not deeply committed to prostitution, but saw it as a 
relatively easy way to make a living. When conditions 
changed so did their involvement and many seem to 
have given up "the game" (Step 50). 

 Redesign of a trolley stop to curb robberies and assaults 
resulted in a reduction in violent crime at a San Diego, 
California location without shifting these crimes to other 
trolley stops. 

In these examples and numerous others, the offenders' 
costs of displacing seemed to have outweighed the 
benefits and the examples bear out the argument that 
displacement occurs much less than commonly believed. 
This is the consensus of four different reviews of the 


displacement literature undertaken in the United 
Kingdom, Canada, the United States, and The 
Netherlands. The Dutch review (the most recent one) 
reports that in 22 of 55 studies from around the world in 
which displacement was examined, no evidence of it was 
found. In the remaining 33 studies, in which evidence of 
displacement was found, only some of the crime seems to 
have been displaced. In no case was the amount of crime 
displaced equal to the amount prevented. And in no case 
did displacement increase crime. 

Displacement is usually limited because offenders have 
difficulty adapting quickly. If they do make changes they 
are most likely to change to places, times, targets, 
methods, and crime types that are similar to those the 
prevention program blocks because these are the easiest 
changes for them to make. This suggests that 
displacement can be predicted by anticipating the easiest 
changes for offenders to make. If there are obvious easy 
changes, then you should consider how to incorporate 
these in your prevention plan. And if you cannot include 
them, then you should consider monitoring them to detect 
possible displacement. 

To sum up, displacement is always a threat, but there are 
strong theoretical reasons for believing that it is far from 
inevitable. In addition, the studies of displacement show 
that even when it does occur, it may be far from complete 
and that important net reductions in crime can be 
achieved by opportunity-reducing measures. 

Read More: 

Hesseling, Rene (1994). "Displacement: A Review of the 
Empirical Literature." Crime Prevention Studies, volume 
3, edited by Ronald Clarke. Monsey, NY: Criminal Justice 
Press (accessible at www.popcenter.org). 

Claims of Displacement Often Evaporate under 
Closer Scrutiny 

In the mid-1980s, John Eck observed a displacement 
dispute within the Newport News Police Department 
(VA). A crackdown on a street corner marijuana market 
resulted in the market's closure. Some police officials 
asserted that the offenders had merely moved to a 
nearby corner to deal drugs. However, close inspection 
by other officers revealed several important facts: 
 The nearby corner dealers were selling heroin, not 
marijuana. 
 None of the offenders from the marijuana market 
were found at the heroin market. 
 The heroin market was a much smaller scale 
operation. 
 It predated the opening of the marijuana market. 
The claims of displacement were probably due to 
selective perception. Prior to the marijuana market, 
street corner drug dealing had been low key and did 
not attract much public notice. Consequently, drug 
markets were not a high police priority. When 
neighborhood members complained about the 
marijuana market, greater attention was paid to other 
drug markets as well. 


13. Expect diffusion of benefits

Researchers looking for displacement have sometimes 
found precisely its reverse. Rather than finding that 
crime has been pushed to some other place or time, 
they have found that crime has been reduced more widely 
than expected, beyond the intended focus of the 
measures. This is a relatively recent discovery, but already 
many examples exist: 

 As expected, electronic tagging of books in a University 
of Wisconsin library resulted in reduced book thefts. 
However, thefts of videocassettes and other materials 
that had not been tagged also declined. 

 When a New Jersey discount electronic retailer 
introduced a regime of daily counting of valuable 
merchandise in the warehouse, employee thefts of these 
items plummeted - but thefts also plummeted of items 
not repeatedly counted. 

 When LoJack vehicle tracking systems were introduced in 
six large cities, rates of theft declined citywide, not just 
for car owners who purchased the devices. 

 Simon Hakim and his colleagues at Temple University 
have shown that widespread ownership of burglar 
alarms in an affluent community near Philadelphia 
resulted in reduced burglary rates for the community 
at large. 

 When red light cameras were installed at certain 
junctions in Strathclyde, a large city in Scotland, not only 
did fewer people run the lights at these locations, but 
also at other traffic lights nearby. (In a smaller city, with 
more local traffic, this effect might be short-lived as 
people learned exactly which junctions had cameras.) 

 The implementation of added security for houses that 
had been repeatedly burgled on a U.K. public housing 
estate in Kirkholt reduced burglaries for the whole of 
the estate, not just for those houses given 
additional protection. 

These are all examples of the "diffusion of benefits" 
resulting from crime prevention measures. It seems that 
potential offenders may be aware that new prevention 
measures have been introduced, but they are often unsure 
of their precise scope. They may believe the measures 
have been implemented more widely than they really 
have, and that the effort needed to commit crime, or the 
risks incurred, have been increased for a wider range of 
places, times, or targets than really is the case. This means 
that diffusion can take several forms, paralleling the 
different kinds of displacement (see table). 

Diffusion of benefits is a windfall that greatly increases 
the practical appeal of situational crime prevention, but 
we do not yet know how to deliberately enhance it. One 
important method may be through publicity. A publicity 
campaign helped to spread the benefits of video 
surveillance cameras across an entire fleet of 80 buses in 
the North of England, although these were installed on 
just a few of the buses. One of the buses with the 
cameras was taken around to schools in the area to show 
students they could be caught if they misbehaved and 
vandalized the bus, and the first arrests resulting from the 
cameras were given wide publicity in the news media. 

Table: Displacement and Diffusion of Benefits for Burglary of Apartments 
Table Headers: Type, Definition, Diplacement, Diffusion
Row Data: 
Geographical, Geographic change, Switch to another building, Reduce burglaries in targeted 
building and in nearby buildings

Temporal, Time switch, Switch from day to evening, Reduce burglaries during day 
and evening 

Target, Switching object of offending, Switch from apartments to houses, Reduce burglaries in apartments 
and houses 

Tactical, Change in method of offending, Switch from unlocked doors to picking locks, Reduction in attacks 
on locked and unlocked doors

Crime Type, Switching crimes, Switch from burglary to theft, Reduction in burglary and theft 
 

We should expect the diffusion of benefits to decay when 
offenders discover that the risks and effort of committing 
crime have not increased as much as they had thought. 
Research has shown that this occurred in the early days of 
the breathalyzer in the U.K., which had a much greater 
immediate impact on drunk driving than expected, given 
the actual increase in the risk of getting caught. However, 
as drivers learned that the risks of being stopped were 
still quite small, drunk driving began to increase again. 
This may mean that ways will have to be found of 
keeping offenders guessing about the precise levels of 
threat, or about how much extra effort is needed if they 
are to continue with crime. 

At a practical level, diffusion is important as a counterargument 
to displacement from those resisting the 
introduction of preventive measures. And you will certainly 
encounter many of those! Second, it is important that you 
plan your evaluation to take account of diffusion. Ways to 
do this are discussed in Step 51, by using two sets of 
control areas, both near and more distant. Otherwise, you 
might find that people question the effectiveness of the 
preventive initiative on grounds that crime fell across a 
broader area than was targeted. 

Read More: 

Clarke, Ronald and David Weisburd (1994). "Diffusion of 
Crime Control Benefits: Observations on the Reverse of 
Displacement". Crime Prevention Studies, volume 2. 
Monsey, NY: Criminal Justice Press 
(accessible at www.popcenter.org). 

Diffusion of Benefits and Video Surveillance in a University's Parking Lots

A new head of security at the University of Surrey in the U.K. decided to deal with a plague of thefts in the 
university's parking lots by introducing video surveillance (or CCTV - closed-circuit television). He installed a CCTV 
camera on a mast to provide surveillance of the parking lots. As the diagram shows, the camera could not provide 
surveillance equally for all four parking lots because buildings obscured its view of parking lot 1. 

Image of parking lot map

It might have been expected, therefore, that if the camera had any value in preventing crime this would only be for 
the parking lots it covered adequately. It might also have been expected that crime would be displaced by the 
camera from these parking lots to the one not given proper surveillance. In fact, in the year following the 
introduction of the camera, incidents of theft and vandalism in the lots were cut in half, from 138 in the year prior to 
65 in the year after. Incidents declined just as much in parking lot 1, not covered by the cameras, as in the other 
three lots. This diffusion of the benefits of the video surveillance probably resulted from potential offenders being 
aware that it had been introduced at the university, but not knowing its limitations. Many probably decided that it 
was no longer worth the risk and effort of going to the university parking lots to commit crime. 
 
Source: Poyner, Barry (1997). "Situational Prevention in Two Parking Facilities". Situational Crime Prevention: 
Successful Case Studies, edited by Ronald V. Clarke. Monsey, NY: Criminal Justice Press. 


14. Use the CHEERS test when defining problems

A problem is a recurring set of related harmful events 
in a community that members of the public expect 
the police to address. This definition draws 
attention to the six required elements of a problem: 
Community; Harm; Expectation; Events; Recurring; and 
Similarity. These elements are captured by the 
acronym CHEERS: 

 Community. Members of the public must experience 
the harmful events. They include individuals, businesses, 
government agencies, and other groups. Only some not 
all or most - community members need experience 
the problem. 

 Harmful. People or institutions must suffer harm. The 
harm can involve property loss or damage, injury or 
death, serious mental anguish, or undermining the 
capacity of the police (as in repeat fraudulent calls for 
service). Illegality is not a defining characteristic of 
problems. Some problems involve legal behavior that 
the police must address. Noise complaints arising from 
the impact of legitimate commercial activity on 
neighboring residents is a common example. Some 
problems are first reported as involving illegal behavior, 
but on closer inspection do not involve illegalities. If 
such reports meet all the CHEERS criteria, they 
are problems. 

 Expectation. Some members of the community must 
expect the police to address the causes of the harm 
(their numbers do not have to be large). Expectation 
should never be presumed, but must be evident through 
processes such as citizen calls, community meetings, 
press reports, or other means. This element does not 
require the police to accept at face value the public's 
definition of the problem, their idea of its causes, or 
what should be done about it. The public may be 
mistaken as to its cause and characteristics. It is the 
role of analysis to uncover the causes. 

 Events. You must be able to describe the type of event 
that makes up the problem. Problems are made up of 
discrete events. Examples of events include a break-in 
at a home, one person striking another, two people 
exchanging money and sex, or a burst of noise. Most 
events are brief, though some may involve a great deal 
of time - some frauds, for example. 

 Recurring. These events must recur. Recurrence may 
be symptomatic of acute troubles or a chronic problem. 
Acute troubles suddenly appear, as in the case of a 
neighborhood with few vehicle break-ins suddenly 
having many such break-ins. Some acute troubles 
dissipate quickly, even if nothing is done. Others can 
become chronic problems if not addressed. For this 
reason, acute troubles should be investigated to 
determine if they signal something more entrenched. 
Chronic problems persist for a long time, as in the case 
of a prostitution stroll that has been located along one 
street for many years. Unless something is done, the 
events from chronic problems will continue to occur. 

 Similarity. The recurring events must have something in 
common. They may be committed by the same person, 
happen to the same type of victim, occur in the same 
types of locations, take place in similar circumstances, 
involve the same type of weapon, or have one or more 
other factors in common. Without common features, you 
have an arbitrary collection of events, not a problem. 
Common crime classifications - such as used by the 
Uniform Crime Reports - are not helpful. Vehicle theft, 
for example, includes joyriding, thefts for chop shops, 
thefts for export to other countries, thefts for use in 
other crimes, and a host of other dissimilar events. So a 
cluster of vehicle thefts may not be a single problem. 
More information is needed. With common features, we 
have a pattern of events that could indicate a problem for 
example, thefts of minivans in suburban 
neighborhoods to be used as gypsy cabs in the 
inner city. 

Problems need to be examined with great specificity (see 
Steps 6 and 15) because small details can make a 
difference between a set of circumstances that gives rise 
to harmful events, and a set of circumstances producing 
harmless events. CHEERS suggests six basic questions 
you need to answer at the scanning stage: 

 Who in the community is affected by the problem? 
 What are the harms created by the problem? 
 What are the expectations for the police response? 
 What types of events contribute to the problem? 
 How often do these events recur? 
 How are the events similar? 


Not everything the police are asked to address is a 
problem. CHEERS can help identify demands that are not 
problems. We are using the term "problem" in the 
technical, POP sense, not as we would in everyday 
speech. So things that are not problems may be 
troublesome and may require police attention. These are 
as follows: 

 Single events. A single event, regardless of how 
serious, is not a problem unless there is a reasonable 
prospect that another similar event will occur if nothing 
is done. A single event may deserve investigation or 
some other police action, but problem solving cannot be 
applied to isolated events because nothing can be 
prevented. 

 Neighborhoods. Small areas, such as city centers or 
particular residential apartment complexes, sometimes 
get reputations as problems, but these neighborhoods 
are seldom problems. Rather they are usually areas 
containing several problems. The individual problems 
might be related, but not always. Tackling an entire area 
as a single problem increases the complexity of the 
effort and reduces the chances you will find effective 
responses. Instead, you should identify specific problems 
within a neighborhood and tackle them individually. If 
the problems are linked (e.g., the street network 
contributes to several problems) then tackling the link 
might be helpful. Do not assume problems are linked 
just because they are near each other. In some cases, of 
course, there may be common solutions to distinct 
problems (see Step 6). 

 Status conditions. Truant schoolchildren, bored 
teenagers, vagrant adults, and convicted criminals are 
not problems because of their status of not being in 
school, having nothing to do, not being employed, or 
having been found guilty of an offense. A community 
might expect the police to do something about them, 
but status conditions lack the characteristics of harm 
and events. Some of these people may play a role in 
problems, as targets, offenders, or in some other 
capacity, but that does not make them a problem. 
Defining a problem by status conditions is evidence of 
lack of precision and a need to examine the issue in 
greater depth. Status conditions may point to pieces of 
a larger problem. 

Always use the CHEERS test - does the possible problem 
have all six elements? If it does not, it is probably not a 
suitable focus for a problem-oriented policing project. 


15. Know what kind of problem you have

Because local police have to deal with a wide range 
of problems that meet the CHEERS definition (Step 
14) we have developed a classification for these 
problems. This classification scheme can help you precisely 
define the problem. It helps separate superficially similar 
problems that are really distinct. It also allows you to 
compare your problem to similar problems that have 
already been addressed, and it helps identify important 
features for examination. For example, an extensive set of 
guides to addressing common problems are available from 
the Office of Community Oriented Policing Services and 
the Center for Problem-Oriented Policing websites (Step 
19). Knowing the type of problem you are investigating 
can help you identify guides that might be helpful, even if 
they do not directly address your problem. The 
classification scheme is based on two criteria: the 
environments within which problems arise, and the 
behaviors of the participants. (The scheme is different 
from the wolf/duck/den classification in Step 8, which is a 
classification of persistent problems.) 

Environments regulate the targets available, the 
activities people can engage in and who controls the 
location. Specifying an environment allows comparisons of 
environments with and without the problem. 
Environments have owners who can be important for 
solving the problem (see Step 44). There are 11 distinct 
environments for most common police problems: 

 Residential - Locations where people dwell. Houses, 
apartments, and hotel rooms are examples. Though most 
are in fixed locations, a few are mobile, such as 
recreational vehicles. 

 Recreational - Places where people go to have a good 
time. Bars, nightclubs, restaurants, movie theaters, 
playgrounds, marinas, and parks are examples. 

 Offices - Locations of white-collar work where there is 
little face-to-face interaction between the workers and 
the general public. Government and business facilities 
are often of this type. Access to these locations is 
often restricted. 

 Retail - Places for walk-in or drive-up customer traffic 
involving monetary transactions. Stores and banks 
are examples. 

 Industrial - Locations for processing of goods. Cash 
transactions are not important activities in these 
environments and the public is seldom invited. Factories, 
warehouses, package-sorting facilities are examples. 

 Agricultural - Locations for growing crops and 
raising animals. 

 Education - Places of learning or study, including day 
care centers, schools, universities, libraries, and place 
of worship. 

 Human services - Places where people go when 
something is wrong. Courts, jails, prisons, police stations, 
hospitals and drug treatment centers are examples. 

 Public ways - Routes connecting all other environments. 
Roads and highways, foot-paths and bike trails, and 
drives and parking facilities are examples. 

 Transport - Locations for the mass movement of people. 
These include buses, bus stations and bus stops, 
airplanes and airports, trains and train stations, ferries 
and ferry terminals, and ocean liners and piers. 

 Open/transitional - Areas without consistent or regular 
designated uses. These differ from parks in that they 
have not been designated for recreation, though people 
may use them for this. Transitional areas include 
abandoned properties and construction sites. 

Behavior is the second dimension for classifying a 
problem. Specifying behaviors helps pinpoint important 
aspects of harm, intent, and offender-target relationships. 
There are six types of behavior: 

 Predatory - The offender is clearly distinct from the 
victim and the victim objects to the offender's actions. 
Most common crimes are of this type. Examples include 
robbery, child abuse, burglary, bullying, and theft. 

 Consensual - The parties involved knowingly and 
willingly interact. This typically involves some form of 
transaction. Examples include drug sales, prostitution, 
and stolen goods sales. Note, however, that assaults on 
prostitutes are predatory behaviors. 

 Conflicts - Violent interactions involving roughly coequal 
people who have some pre-existing relationship. Some 
forms of domestic violence among adults involve this 
type of behavior, though domestic violence against 
children and the elderly is classified as predatory 
because the parties involved are not coequal. 

 Incivilities - Offenders are distinguishable from victims 
but the victims are spread over a number of individuals 
and the harms are not serious. Many concerns that are 


annoying, unsightly, noisy, or disturbing, but do not 
involve serious property damage or injury fall into this 
category. Loud parties are an example. Whether 
vandalism fits in this category depends on the details. 
Some forms of vandalism are predatory. Some 
incivilities are troublesome regardless of the 
environment, while others are only troublesome in 
specific environments. 

 Endangerment - The offender and the victim are the 
same person or the offender had no intent to harm the 
victim. Suicide attempts, drug overdoses, and vehicle 
crashes are examples. 

 Misuse of police - A category reserved for unwarranted 
demands on the police service. False reporting of crimes 
and repeated calling about issues citizens can handle 
themselves are examples. This is a category of last resort 
-for use when the sole harm stemming from the
behavior is the expenditure of police resources and
when none of the other categories fit.

The table shows the full classification. A problem is 
classified by putting it in the cell where the appropriate 
column intersects with the appropriate row. So, for 
example, the 2001 Tilley Award winner dealt with glass 
bottle injuries around pubs, a conflict-recreational 
problem (A). Officers in San Diego had to deal with repeat 
fraudulent calls of gang member threats at a convenience 
store (B). Notice how this differs from the 2003 Goldstein 
award runner-up, addressing stores selling alcohol to 
minors in Plano, Texas (C). The 2002 Goldstein Award 
winner dealt with motor vehicle accidents involving 
migrant farm workers, an endangerment-public ways 
problem (D). The 1999 Goldstein Award winner dealt 
with litter and vagrancy, a public way/incivility problem 
(E). Consider the difference between a problem of street 
corner drug sales (F) and a robbery-retaliatory shooting 
problem stemming from disputes between the dealers (G). 
These two problems overlap, but they are not the same. 

Though most problems fit into a single cell, on occasion a 
problem might involve multiple behaviors or 
environments. For example, the Staffordshire Police 
(England) had a problem created when protesters 
occupied abandoned buildings along a construction right 
of way. These were open/transitional environments. The 
protests involved incivilities, but the tactics for occupying 
these buildings also posed a danger to the protesters. 
Thus, endangerment was another relevant behavior (H in 
the table). Though multiple types of behaviors or 
environments are sometimes needed, excessive use of 
multiple types can lead to imprecision. 

By classifying problems, police agencies can compare 
separate problem-solving efforts that occur in the same 
environments and involve the same category of behavior. 
Are there common analysis issues or effective responses 
to these problems? Do analysis and response issues for 
problems of this type differ from other types of problems? 
Answering questions like these can improve problem 
solving as well as problem-solving training, and help us 
increase our understanding of what might work for 
different types of problems in different types 
of environments. 

Read More: 

Eck, John and Ronald Clarke (2003). "Classifying 
Common Police Problems: A Routine Activity Approach." 
Crime Prevention Studies, volume 16, edited by Martha 
Smith and Derek Cornish. Monsey, NY: Criminal 
Justice Press. 

Table: A Classification Scheme for Common Problems Facing Local Police
Table Headers: ENVIRONMENTS, BEHAVIORS
Second Row Table Headers: Predatory, Consensual, Conflicts, 
Incivilities, Endangerment, Misuse of Police 
Row Data:
Residential - none
Recreational - conflicts
Offices - none
Retail - consensual, misuse of police
Industrial - none
Agricultural - none
Educational - none
Human service - none
Public ways - predatory, consensual, incilivities, endangerment
Transport - none
Open/Transition - incivilities, endangerment


16. Study the journey to crime

While the problem analysis triangle (Step 8) 
identifies the three essential elements of crime, it 
does not explain how offenders find suitable 
targets. According to Marcus Felson, they do this in three 
main ways: 

1. Through personal knowledge of the victim (your 
neighbor's son might know when you are away from 
your house). 

2. Through work (a burglar working as a telephone 
engineer might overhear that you will be taking 
vacation next week). 

3. Through overlapping "activity spaces." 

The concept of activity spaces is central to crime pattern 
theory, which was developed by the Canadian 
environmental criminologists Pat and Paul Brantingham 
(see figure). They use the concept to describe how 
offenders find targets in the course of their daily routines. 
Starting with a triangle, they consider offenders going 
from home to work to recreation. Around each of these 
three nodes and along each of these three paths 
(excepting a buffer zone where they might be recognized) 
offenders look around for crime opportunities. They may 
find these a little way off the path, but they usually do not 
go far beyond the area they know. This is because it is 
easier to commit crimes in the course of their daily routine 
than by making a special journey to do so. 

The Brantinghams also use the term edges to refer to the 
boundaries of areas where people live, work, shop, or 
seek entertainment. Some crimes are more likely to occur 
at these edges - such as racial attacks, robberies, or 
shoplifting - because this is where people from different 
neighborhoods who do not know each other come 
together. In an early study, the Brantinghams found that 
residential burglaries in Tallahassee, Florida tended to 
cluster where affluent areas bordered on poor areas. Their 
explanation was that the affluent areas provided 
attractive targets to burglars from the poorer areas, but 
the burglars preferred not to venture too far into them 
because they were unfamiliar with the territory and might 
be recognized as not belonging there. They would also be 
more vulnerable because they would have further to travel 
with the proceeds of the crime. 

The paths that people take in their everyday activities and 
the nodes they inhabit explain risks of victimization as 
well as patterns of offending. This is why the 
Brantinghams and other crime pattern theorists pay so 
much attention to the geographical distribution of crime 
and the daily rhythm of activity. For example, these 
researchers generate crime maps for different hours of the 
day and days of the week, linking specific kinds of crimes 
to commuter flows, school children being let out, store 
closing hours, or any other process that moves people 
among nodes and along paths. Pickpockets and some 
shoplifters seek crowds, while other offenders pay closer 
attention to the absence of people. For example, the flow 
of people to work generates a counterflow of burglars to 
residential areas, taking advantage of the commuters' 
absence. The flow of workers home at night and at 
weekends produces a counterflow a few hours later of 
burglars targeting commercial and industrial sites. 

Many studies have shown that the journey to crime is 
typically very short - offenders generally commit crimes 
within 1 or 2 miles of their homes. For example, Andy 
Brumwell, a crime analyst with the West Midlands Police, 
one of the U.K.'s largest police forces, has recently 
completed an analysis of 258,074 crime trips made over a 
2-year period. He found the following: 

 About half the journeys were less than a mile. (In most 
U.S. studies the journeys might be a little longer because 
of lower population densities and greater access to 
vehicles.) 

 Distance traveled varied with the offense. For example, 
shoplifters tended to travel further than many other 
kinds of offenders. 

 Females traveled further than males, possibly because 
many committed shopliftings. 

 Individual offenders varied considerably in crime trips. 
Some usually committed crimes in their local 
neighborhoods. Others traveled further, particularly 
when working with co-offenders. 

 The youngest offenders committed crime very close to 
home, while those in their 20s traveled the furthest. 

Susan Wernicke, a crime analyst with the City of Overland 
Park, Kansas, presented more detailed information on 
juveniles at the National Institute of Justice's 2000 
National Crime Mapping Conference in San Diego, 
California. She showed that in Overland Park the 11-yearolds 
arrested had committed crimes an average of 1.05 
miles from home. This distance gradually increased with 
age, and by age 17 was 2.7 miles. She attributed part of 
the increase to greater access to cars. 



You can use the concepts of crime pattern theory to 
understand crime in your jurisdiction. You should try to 
piece together offender and offense patterns by finding 
nodes, paths, and edges. You can begin to distinguish 
between how offenders search for crime and when they 
find it by accident. You can find where offenders are 
absent and where they congregate in hot spots and think 
about the reasons for this (Step 17). You will find that 
very local crime patterns tell the story. Thus a high-crime 
district will have some streets with no crime at all and 
some addresses which generate most of the problem. 
Residents may know it is fairly safe to walk down one 
street but not to walk down another. They may even 
choose one side of the street over the other. If residents 
know their local turf this well, what's to stop you from 
finding out about it? Crime pattern theory helps you do 
just that, and it will help to define a specific problem at 
the scanning stage and understand the contributory 
causes at analysis. 

The Journey to Crime and the Self-Containment

Andy Brumwell has developed the "self-containment 
index," which looks at the percentage of crimes in an 
area that is committed by offenders who also live in 
that area. A value of 100 indicates that local offenders 
are responsible for all the crimes, whereas a value of 
zero indicates that local offenders commit none of 
them. This value should be calculated when analyzing a 
local problem. Whether predators are local or come 
from a distance will have an influence on the type of 
situational crime prevention measures that could be 
successfully introduced. For example, closing streets in a 
particular neighborhood will only be effective if many of 
the offenders drive to the neighborhood to commit 
crime. 
 
Read More: 

Brantingham, Patricia and Paul (1993). "Environment, 
Routine, and Situation: Toward a Pattern Theory of 
Crime." Routine Activity and Rational Choice, Advances 
in Criminological Theory, volume 5, edited by Ronald 
Clarke and Marcus Felson. New Brunswick, NJ: 
Transaction Publishers. 

Felson, Marcus (2002). Crime and Everyday Life. Thousand 
Oaks, CA: Sage. 

Wiles, Paul and Andrew Costello (2000). The Road to 
Nowhere: The Evidence for Travelling Criminals. Home 
Office Research Study 207. London: Home Office 
(accessible at www.homeoffice.gov.uk) 

Brantingham Crime Pattern Theory 
Kim Rossmo prepared this diagram to represent the Brantinghams' theory. It shows an offender's activity space (residence, work, recreation, and the 
travel routes between them), the buffer zone close to the home in which offenders do not usually commit crimes, and five potential target areas (for 
example, parking lots). Where an offender's activity space intersects a target area, this is where crimes happen (crosses). Note that in this example no 
crimes occur around the offender's workplace, because there are no suitable targets there. Also, there are two target areas with no crimes in them 
because this offender is not aware of those places. 

Source: Rossmo, Kim (2000). Geographic Profiling. Boca Raton, FL: CRC Press. 


17. Know how hot spots develop

Analysts often examine hot spots by use of 
geography alone. This can often be a useful 
starting point, but to reduce or eliminate the hot 
spot you must look deeper to understand why it is a hot 
spot. We focus on developing an understanding of the 
processes that create hot spots. Later, in Steps 23 and 
55, we examine how to analyze and map hot spots 
without letting your mapping software call the shots. As 
we have seen in previous steps, small areas - places - are 
critical to understanding many problems and developing 
effective responses. We, therefore, focus on hot spot 
places in this step. In later steps we will build on this 
idea to examine hot spot streets and areas. 

There are three kinds of hot spot places, each with its 
own underlying causal mechanisms: 

 Crime generators are places to which large numbers 
of people are attracted for reasons unrelated to criminal 
motivation. Providing large numbers of opportunities for 
offenders and targets to come together in time and 
place produces crime or disorder. Examples of 
generators include shopping areas, transportation hubs, 
festivals, and sporting events. The large number of crime 
or disorder events is due principally to the large number 
of place users and targets. 

 Crime attractors are places affording many criminal 
opportunities that are well known to offenders. People 
with criminal motivation are drawn to such locales. In 
the short run, offenders may come from outside the 
area, but over longer time periods, and under some 
circumstances, offenders may relocate to these areas. 
Prostitution and drug areas are examples. Some 
entertainment spots are also well known for allowing 
deviant activity. Such places might start off being known 
only to locals, but as their reputation spreads increasing 
numbers of offenders are drawn in, thus increasing the 
number of crime and disorder events. 

 Crime enablers occur when there is little regulation of 
behavior at places: rules of conduct are absent or are 
not enforced. The removal of a parking lot attendant, for 
example, allows people to loiter in the parking area. This 
results in an increase in thefts from vehicles. This is an 
example of an abrupt change in place management. 
Sometimes place management erodes slowly over time, 
leading to problem growth. Crime enablers also occur 
with the erosion of guardianship and handling. For 
example, if parents attend a play area with their children 
they simultaneously protect the children (guardianship) 
and keep their children from misbehaving (handling). If 
parenting styles slowly change so that the children are 
increasingly left to themselves, their risk of victimization 
and of becoming offenders can increase. 

Patricia and Paul Brantingham suggest that areas can be 
crime neutral, i.e., they attract neither offenders nor 
targets, and controls on behaviors are adequate. These 
areas tend to have relatively few crimes, and the crimes 
tend to be relatively unpatterned. For this reason, crime-
neutral areas seldom draw police attention. Though they 
seldom require crime analysis, they are important because 
they provide a useful comparison to the other types of 
areas. Comparing crime-neutral areas, for example, to a 
hot spot can help identify the differences that create the 
troubles in the crime generator, crime attractor, or crime 
enabler. Case-control studies (Step 32) are useful for 
this purpose. 

In summary, when a crime or disorder hot spot becomes a 
greater problem it is generally because the number of 
targets has increased, the number of offenders taking 
advantage of the hot spot have increased, or because the 
level of control being exercised at the site declined. Often, 
all three are at work. Shoppers might increase in an area, 
for example, due to new roads. This might lead to 
increased thefts as offenders take advantage of the new 
theft opportunities. Successful offending might attract new 
offenders. Increased offending might cause the number 
of shoppers to decline. This removes guardianship 
(shoppers). But it has another effect. It could reduce 
place management as the resources of the businesses 
decline. So, a problem that started out as a crime 
generator evolved into a crime attractor and then into a 
crime enabler. 

We can compare numbers and rates to diagnose which of 
these mechanisms may be operating. Dividing the crimes 
in question by the number of possible crime targets 
creates rates (Step 27). This is often expressed as the 
number of crimes per 100 targets available. So, for 
example, if a parking lot has 15 car break-ins during a 
year, and the lot contains 150 spaces and operates at 
near capacity, its break-in rate is 15/150 or .1. This 
translates to 10 break-ins per space per year. Note that 
this analysis is only useful if the lot is operating near 
capacity. If only 50 spaces are used on most days, then 
the rate is three times as high (15/50=.3 or 30 break-ins 
per vehicle per year). 


Table 1 illustrates the differences in ranking the 
importance of hot spots depending on whether numbers 
or rates are used. Place A is the "hottest" spot in terms 
of numbers but second in terms of rates, and place C goes 
from third hottest to first when one switches from 
numbers to rates. 

Let's look at how hot spot mechanisms generate 
indicative combinations of numbers and rates. Crime 
generators have many crimes, but as their number of 
targets is high, they have low crime rates (Place B in Table 
1). Crime attractors also have many crimes, but as they 
have relatively few targets, their crime rates are high 
(Place A). Crime enablers, with their weakened behavior 
controls, tend to be unattractive to targets. However, 
those few available targets have high risks. So a place 
with relatively few crimes but a high crime rate suggests a 
crime enabler (Place C). Finally, the number of crimes at 
crime-neutral locations will be low, so even if the number 
of targets is not particularly great, their crime rate will 
also be low (Place D). Table 2 summarizes 
these relationships. 

The rankings of numbers and rates are relative, so this 
process is useful for comparison purposes. And there may 
be multiple mechanisms operating. Low behavioral 
controls (enabler) may also attract offenders (attractor), 
for example. Nevertheless, such comparisons provide an 
early indicator of how to proceed and establish 
hypotheses for later examination (see Step 20). Such 
analysis will help suggest the types of responses that 
could be effective. This is summarized in Table 3. 

Read More: 

Brantingham, Patricia and Paul (1995). "Criminality of 
Place: Crime Generators and Crime Attractors". European 
Journal on Criminal Policy and Research 3(3):1-26. 

Table 1: Numbers and Rates 
Table Headers: Place, Crimes, Targets, Rate Per 100 targets 

A, 341, 898, .350, 35 
B , 148, 1795, .082, 8
C, 117, 243, .481, 48 
D, 28, 638, .044, 4 
 
Table 2: Diagnosing Hot Spot Mechanisms 
Table Headers: Number, Rate

Crime Attractors: High, High 
Crime Generators: High, Low 
Crime Enabler: Low (High), High 
Crime Neutral: Low, Low 
 
Table 3: What To Do about Worsening Hot Spots
Table Headers: Hot spot type, Cause, Type of Response, Questions to Answer
Row Data:
Crime Generator: Many unprotected targets, Increase protection, In what circumstances are 
targets vulnerable? How can vulnerability be changed?   

Crime Attractor: Attract offenders, Discourage offenders from coming, What is attracting 
offenders? How can this be changed? 
 
Crime Enabler: Erosion of controls, Restore guardianship, handling or place management,  
Who could control behaviour? How can they be encouraged to exert controls? 
 

18. Learn if the 80-20 rule applies

Avery important principle of crime prevention is that 
crime is highly concentrated on particular people, 
places, and things. This suggests that focusing 
resources where crime is concentrated will yield the 
greatest preventive benefits. These concentrations (dealt 
with in more detail in later steps) have attracted labels 
that are becoming well known to most crime analysts: 

 Repeat Offenders In Wolfgang's famous Philadelphia 
cohort, about 5 percent of all offenders in the study 
were responsible for more than 50 percent of the 
crimes. 

 Repeat Victims According to the British Crime Survey, 
repeat victims (just over 4 percent of all victims) endure 
40 percent of the crimes reported in the survey (see 
Step 29). 

 Hot Spots In the landmark paper that put this concept 
on the map, so to speak, Lawrence Sherman and 
colleagues found that 6 percent of the addresses in 
Minneapolis accounted for 60 percent of the calls for 
police service. 

 Hot products Annual data produced by the Highway 
Loss Data Institute show that theft claims for some 
automobile models are as much as 30 times greater 
than for other cars (see Step 31). 

 Risky Facilities In Danvers, Massachusetts, 3 out of 78 
stores (5 percent) accounted for 55 percent of 
shoplifting incidents reported to the police (see 
Step 28). 

This kind of concentration is not peculiar to crime and 
disorder, but is almost a universal law. A small portion of 
the earth's surface holds the majority of life on earth. Only 
a small proportion of earthquakes cause most of the 
earthquake damage. A small portion of the population 
holds most of the wealth. A small proportion of police 
officers produce most of the arrests. 

This phenomenon is commonly called the 80-20 rule, 
where in theory 20 percent of some things are responsible 
for 80 percent of the outcomes. In practice, it is seldom 
exactly 80-20, but it is always a small percentage of 
something or some group involved in a large percentage 
of some result. The table shows this rule in practice. It 
reports an analysis made by Stacy Belledin of construction 
site thefts and burglaries for 55 homebuilders in 
Jacksonville, Florida. Eleven of the builders (20 percent of 
the group) experienced between them 85 percent of all 
the thefts and burglaries at construction sites reported to 
the Jacksonville Sheriffs Department during January-
September 2004. 

In investigating any problem, you should therefore always 
ask if the 80-20 rule applies. A simple six-stage procedure 
shows how to answer this: 

1. Make a list of the people, places, or products, with a 
count of the number of events associated with each 
of these. 

2. Rank order them according to the number of events
associated with each - most to least.

3. Calculate the percentages of the events each person, 
place, or product contributes. In the table, there are 
386 incidents of theft and burglary. Sixty of these 
incidents (15.5 percent) occurred at construction sites 
owned by Builder 1. 

4. Cumulate the percentages of incidents starting with 
the most involved person, place or product (or in this 
example, home builders). 

5. Cumulate the percentages of the people, places, or 
products (in our example, the cumulative percentage 
of home builders in column 5). 

6. Compare the cumulative percentages of people, 
places, or products (column 5) to the cumulative 
percentage of outcomes (column 4). This shows how 
much the most involved people or places contribute 
to the problem. 

These kinds of calculations can be very helpful at the 
scanning stage in directing preventive effort. Thus, in the 
Jacksonville example, just five builders experienced more 
than 50 percent of the incidents. In theory, focusing 
preventive action on these five builders, rather than on 
the total group of 55, could be a very efficient strategy for 
reducing the city's overall problem of theft and burglaries 
in construction sites. 

At the analysis stage, these kinds of tables can help in 
determining if there are important differences among 
people, places, or products at the top and those at the 
bottom of the list. In our example, Stacy Belledin found 
that an approximate measure of the numbers of homes 
built correlated fairly well with the numbers of thefts and 
burglaries experienced by each builder, but it did not 
explain all the differences in risk. Other possibly important 
sources of these differences could be the neighborhoods 
where builders were operating, their police reporting 
practices and their standard security precautions. 


Reported Thefts and Burglaries at Construction Sites 
55 Home Builders, Jacksonville, FL , Jan. - Sept 2004 
Table Headers: 1 Home Builder, 2 Incidents, 3 Percentage of Incidents,
4 Cumulative Percentage of Incidents, 5 Cumulative Percentage of Builders 
Row Data:
1, 60, 15.5%, 15.5%, 1.8% 
2, 39, 10.1%. 25.7%, 3.6% 
3, 38, 9.8%, 35.5%, 5.5% 
4, 34, 8.8%, 44.3%, 7.3% 
5, 34, 8.8%, 53.1%, 9.1% 
6, 31, 8.0%, 61.1%, 10.9% 
7, 29, 7.5%, 68.7%, 12.7% 
8, 26, 6.7%, 75.4%, 14.6% 
9, 19, 4.9%, 80.3%, 16.4% 
10, 11, 2.9%, 83.2%, 18.2% 
11, 8, 2.1%, 85.2%, 20.0% 
12, 7, 1.8%, 87.1%, 21.8% 
13, 7, 1.8%, 88.9%, 23.7% 
14, 6, 1.6%, 90.4%, 25.5% 
15, 5, 1.3%, 91.7%, 27.3% 
3 Builders 4 Incidents, 12, 3.0%, 94.8%, 32.7% 
3 Builders 3 Incidents, 9, 2.4%, 97.2%, 38.2% 
1 Builders 2 Incidents, 2, 0.5%, 97.7%, 40.0% 
9 Builders 1 Incident, 9, 2.3%, 100.0%, 56.4% 
24 Builders 0 Incidents, 0, 0.0%, 100.0%, 100.0% 
55 builders, 386, 100%, 100%, 100% 


19. Research your problem 

Other police agencies might already have dealt with 
the problem you are tackling or researchers might 
have studied it. You could save a lot of time by 
finding out how they analyzed it and what they did, in 
particular which responses seemed to be effective and 
which not. Studying the efforts of others can provide you 
with useful hypotheses to test on your problem (Step 20). 

Begin with the Problem-Oriented Guides for Police (POP 
Guides) available online at www.cops.usdoj.gov and 
www.popcenter.org. Each guide summarizes the research 
on a particular problem and discusses ways of responding 
to it. (The website versions of the guides include links to 
source materials that are not available with the print 
versions.) New guides are continually being produced, but 
if there is not one on your problem, look for related 
guides. For example, there is presently no guide on drug 
dealing in public housing, which might be the problem 
you are tackling. However, guides are available on "Drug 
dealing in privately-owned apartment complexes" and 
"Open-air drug markets," and reading them could 
be helpful. 

Useful Websites 

To expand your search, visit the websites listed below. 
Don't be tempted to skip those from Australia and the 

U.K. because problem-oriented policing is widely practiced 
in those countries and the crime problems are similar to 
those here. In fact, crime in San Francisco may be more 
like that in Sydney, Australia, than in a small town in 
Louisiana or Tennessee. 

 Center for Problem-Oriented Policing 

(www.popcenter.org). Apart from the POP Guides, the 
website also contains hundreds of reports of problem-
oriented projects submitted over the years for the 
Goldstein and Tilley Awards. The website's search engine 
allows you search these projects by topic and you can 
read and download them. 

 NCJRS Abstracts Database 

(http://abstractsdb.ncjrs.gov). Only a small proportion of 
the abstracts on this huge database deal directly with 
policing, but it might contain material useful to you. 
Abstracts are sometimes linked to the full text of the 
article or report, which you can download. In other 
cases, you can ask to borrow a copy. This service is free 
and efficient - it generally takes no more than 2 to three 
weeks to receive the material. 

 The Home Office, United Kingdom 
(www.homeoffice.gov.uk). The Home Office, roughly 
equivalent to the U.S. Department of Justice, undertakes 
and sponsors excellent research on police topics. Start 
with a "quick search" using the search box on the 
home page. A summary is given for each entry. Clicking 
on this will take you to the full text. 

 Crime Reduction Website, Home Office 
(www.crimereduction.gov.uk). Browse the "toolkits" 
and "mini-sites," which provide practical guidance in 
dealing with many crimes including robbery, residential 
burglary, domestic violence, street crime, and 
victimization of college students. 

 Australian Institute of Criminology 
(www.aic.government.au). Begin searching this website 
from the opening page. A short description is provided 
of each entry yielded by the search. You can get a fuller 
description by clicking on the title. Full text downloads 
are available of many of the documents. 

Other Useful Resources 

 Google. If the websites yield little of value, try 
"googling" the problem. Google is considered the 
premier search tool on the Internet. To enter a query, 
just type in a few descriptive words and click on the 
search button for a list of relevant web pages. These are 
listed in order of importance as calculated by the 
number of links to the site. Narrowing your search is as 
simple as adding more words to the search terms that 
you have already entered. Your new query will return a 
smaller subset of the pages found for your original "toobroad" 
query. 

 Other police departments. If you find that other 
police departments have tackled the same problem as 
yours, try calling them. Try to speak to the crime analysts 
or officers originally involved in the project. Unless a 
report is available, do not rely too heavily on what you 
are told because memory is notoriously unreliable. 

 Local faculty. Particularly when your local college has a 
criminal justice program, you might obtain useful advice 
from a faculty member. Learn about faculty interests 
from the college website before attempting to contact 
anyone. For anything more than an hour or so of 
consultation, the faculty member might expect 
compensation, although some state universities consider 
assistance to government agencies as part of their 
faculty's regular service mission. 


 National experts. If you repeatedly see an expert's 
name during your search, try e-mailing that person for 
advice. Ask only for specific information that the expert 
can provide quickly. When asking for references, list 
those that you have already found, which will let the 
expert see whether you have missed 
anything important. 

 Interlibrary Loan. Most large public libraries and 
college libraries subscribe to this service, which allows 
them to obtain books and articles that you might need 
from other libraries. You must complete a form that the 
library will supply, and expect to wait about 2 weeks for 
the material to arrive. 

 Criminal Justice Abstracts (CJA). Online access to 
CJA is a vital resource that you will usually find only at 
colleges with a criminal justice program. Try to persuade 
your department to subscribe to it. It covers the major 
journals, books and reports in the field. It provides 
greater coverage of the academic literature than NCJRS 
Abstracts, though the latter provides more coverage of 
government research and professional magazines. 

Limitations of the Information 

Your best sources of information are likely to be (1) 
articles by researchers who have studied the problem you 
are facing and, (2) reports of police projects dealing with 
the problem. However, both have their limitations, 
as follows: 

 Most criminologists are more interested in crime and 
delinquency in general than in specific forms of crime. 
They are also more interested in distant causes of crime, 
such as social disadvantage and dysfunctional families, 
than the near causes of a problem, such as poor security 
or lack of surveillance. So even when you find academic 
articles dealing with your problem, you might find the 
causes they identify help little in developing an 
effective response. 

 Unless your problem is very common, do not expect to 
find many relevant police projects. Be skeptical about 
claims of success unless supported by evaluative data. 
Even projects that have received Goldstein or Tilley 
awards may not have been well evaluated. Be warned 
also that a response that worked in a particular town or 
neighborhood might not work in yours because of 
specific circumstances that make your situation different. 
However, past police experience of dealing with the 
problem is always an important source of ideas about 
what might be helpful in your situation. 

Most academic articles begin with a short Abstract. If 
this looks interesting, read the Summary, Discussion 
and/or Conclusions. If these also seem useful, scan the 
literature review at the beginning of the article. You can 
usually skip the methods sections dealing with data, 
analysis, and results. Even if the article is not directly 
relevant, you might still find useful material listed in the 
References. 

Scanning Academic Articles 
If you need more detailed information for a response (for 
example, CCTV surveillance), returning to your computer 
and the library again should let you find the facts you 
need and enable you to profit from the experience 
of others. 

Read More: 

Clarke, Ronald and Phyllis Schultze (2004). Researching a 
Problem. Problem-Oriented Guides for Police, Problem-
Solving Tool Series No. 2. Washington, DC: Office of 
Community Oriented Policing Services. (accessible at 
www.popcenter.org and www.cops.usdoj.gov). 

Table: Identifying responses
Summarize the responses you identify by constructing a table like that found in the POP 
Guides, with one row for each response and five columns as below: 
Table Headers: Response, Source, How It Works, Works Best If..., Considerations
1 
2 
 

20. Formulate hypotheses

Whenever we confront some new and perplexing 
crime pattern we form hypotheses about its 
causes, often based on incomplete information. 
Experience and theory are good sources of hypotheses. 
You should (1) clearly state your hypotheses, (2) not be 
wedded to them, and (3) use data to objectively test 
them. Expect all hypotheses to be altered or discarded 
once relevant data have been examined because no 
hypothesis is completely right. For this reason it is often 
best to test multiple conflicting hypotheses. 

A set of hypotheses is a roadmap for analysis. Hypotheses 
suggest types of data to collect, how this data should be 
analyzed, and how to interpret analysis results. If you 
were investigating drinking-related assaults in bars you 
might begin with the question, "How many bars are 
problem locations?" Based on the 80-20 rule (Step 18), 
you would state the hypothesis that some bars will have 
many fights, but most will have few or none. You would 
then test this hypothesis by listing the licensed drinking 
places and counting the number of assault reports at each 
over the last 12 months. 

If your hypothesis was supported, you might ask the 
question, "What is different about the bars with many 
fights compared to the bars with few assaults?" The 
concept of risky facilities (Step 28) would help you form a 
set of three hypotheses: 

1. Risky bars have more customers. 
2. Risky bars have features that attract assaulters. 
3. Bar staff in risky bars either fail to control behaviors, or 
provoke fights. 

You can test these hypotheses by gathering data on the 
number of customers at high- and low-risk bars, analyzing 
the number and rate of assaults per customer, observing 
the interactions of people at troublesome and trouble-free 
bars, and interviewing staff and customers. 

If your first hypothesis was contradicted by the data, and 
you found that there was no great difference in numbers 
of assaults across drinking establishments, then you might 
ask the question, why are so many bars troublesome? 
This suggests another hypothesis: It's a perception 
problem; the city has about as many bar assaults as other 
comparable cities. This hypothesis suggests that you will 
need data from comparable cities. 

If, after you collected the relevant data, you found that 
your city has an abnormally high number of problem bars, 
you might ask the question, "What is common to most 
bars in the city that produces a large number of 
assaults?" One hypothesis is that it is the way liquor 
licenses are dispensed and bars regulated. Another 
hypothesis is that there is something about the nature of 
bar customers in your city. Testing each would require you 
to collect relevant data and assess the validity of 
the hypothesis. 

Notice how the questions and hypotheses structure the 
analysis. Test results - positive or negative - reveal new, 
more specific questions. The objective is to start with 
broad questions and hypotheses and, through a pruning 
process, come to a set of highly focused questions that 
point to possible responses. 

Hypotheses suggest the type of data to collect. In the bar 
assaults example, the test of each hypothesis requires 
specific data. Sometimes the same data can test multiple 
hypotheses (as is the case with choosing among the three 
alternative explanations for risky bars). Often a variety of 
data is required to select among alternative hypotheses 
(as is the case with the last set of hypotheses). The more 
specific your hypotheses, the more focused your data 
collection will be. This is why it is more important to have 
a clear hypothesis you personally dislike, than an unclear 
hypothesis you approve of, or worse, no hypothesis at all. 

The lack of explicit hypotheses can lead to "paralysis by 
analysis," collecting too much data, conducting too 
much analysis, and not coming to any useful conclusion. 
Paralysis by Analysis 
Hypotheses can help direct the analysis of data. Every 
clear hypothesis suggests a pattern of data that you 
should be able to observe, if the hypothesis is correct. In 
the example above, the hypotheses derived from the 
concept of risky facilities can be tested using a simple 
analytical procedure. If a bar is a crime generator, then 
you should see a high number of assaults, a high number 
of customers, but a low assault rate (see Step 17). Failure 
to find this pattern suggests the hypothesis is wrong. So 
it is important to have a clear idea of what you should 
observe if your hypothesis is correct, and what you should 
observe if your hypothesis is wrong (see third column of 
the table). If you cannot do this, then this is an indicator 
that your hypothesis may be too vague. 


Hypotheses help interpret the analysis results. Let's 
assume that the analysis of bar fights showed that a few 
bars had most fights, and observations of the high- and 
low-risk bars indicated that the security staff of the risky 
bars provoked fights. This immediately suggests a 
possible avenue for intervention. In short, the validity of a 
hypothesis must make a difference. That is, if the 
hypothesis is true you will take a different decision than if 
it is false. If you will make the same decision regardless of 
the test results, then the hypothesis and its test 
are irrelevant. 

In summary, hypotheses are important for guiding 
analysis. To formulate hypotheses you need to ask 
important questions, then create simple and direct 
speculative answers to these questions. These answers are 
your hypotheses. These speculations must be bold enough 
that they could be wrong, and there must be a way of 
showing whether they are right or wrong. If possible, 
create competing hypotheses. 

Hypothesis formation is a useful group exercise, as it 
allows participants with contrary views to put their 
perspectives on the table in a way that allows clear and 
objective tests. In this way, participants contributing 
invalid hypotheses make substantial contributions to the 
analysis of the problem. If each hypothesis is linked to a 
potential solution, the test of these hypotheses 
simultaneously directs attention to feasible responses and 
rules out ineffective approaches. 

Table: Questions, Hypotheses, and Tests
Table Headers: Question, Example Hypothesis, Possible Test

Why is this place risky?, It is due to a large number of targets 
being available., Count the targets at the location and 
calculate the crime rate. Compare this rate to rates for the surrounding 
area. If the risky place has a higher rate, the hypothesis is false, if it is 
about the same or lower, then the hypothesis is true.

Why are there more car thefts in the problem area than in nearby areas?,  
Residents park their cars on the street, unlike residents of other areas.,
If the problem area has similar or lower on-street parking rates than 
the others, reject the hypothesis. If higher, accept it.

Why did the theft of copper piping from new construction suddenly 
increase?, A new owner bought a nearby scrap metal dealership.,
Compare the thefts of piping before and after the change in owners. If 
the theft rate is the same before and after, or the trend in thefts was 
already going up before the change, then the hypothesis is probably false. 
If otherwise, the hypothesis appears reasonable. 
 

21. Collect your own data

In the course of your routine analytic work, you 
probably use mainly crime incident and arrest data, but 
for problem-oriented projects, you will need to use a 
much wider array of data. For example, calls-for-service 
data could give you a better handle on the amount of 
drug dealing at troublesome locations than arrest data. 
And data kept by the city and by businesses could be 
helpful in analyzing problems of vandalism or shoplifting, 
both of which are poorly measured by police reports. But 
for most problem-oriented projects you will find it 
necessary to go into the field - to use research 
terminology - and gather data yourself. For example, you 
and your project team might have to make systematic 
observations of the environmental features of crime sites; 
you might have to survey victims; and you might have to 
interview offenders or persuade officers to do this for you. 
The need for your own data collection can arise at any 
one of the four stages of SARA as the following 
examples show: 

1. Ronald Clarke was involved in a project focused on 
vehicle-related thefts in downtown parking lots in 
Charlotte, North Carolina. It turned out that the city did 
not have up-to-date maps showing the location of every 
parking lot because new lots were continually being 
opened on the sites of demolished buildings and new 
buildings were being erected on the sites of former lots. 
Consequently, police officers working on the project had 
to survey the entire downtown area to make a complete 
inventory of lots. Later in the project, officers counted 
the spaces in each lot so that the risks of theft per 
parking slot could be calculated. This enabled the lots to 
be ranked for their risks of theft, from highest to lowest. 
Then, in order to explain these variations in risk, officers 
collected detailed information about the security of each 
lot, including the adequacy of its lighting and fencing 
and the use of attendants or security patrols. 

2. In another Charlotte project focused on thefts from 
construction sites, two police officers working on the 
project, Dan Cunius and Eric Rost, regularly checked 
each house in the project to make sure that builders 
were implementing the agreed preventive measures. By 
the time that the study was completed, the officers had 
completed a total of 8,050 separate checks on 
individual houses - a truly enormous data-gathering 
exercise conducted in all kinds of weather. 

3. In a report for the National Law Enforcement & 
Corrections Technology Center, Karin Schmerler, a public 
safety analyst in Chula Vista, Calirfornia, has collected 
some other examples of primary data collection in 
projects submitted for the Goldstein Award for 
Excellence in Problem-Oriented Policing, including 
the following: 

For a project that reduced prostitution-related calls for 
service in Buffalo, New York, the police conducted 15 in-
depth interviews with prostitutes and 116 surveys of 
"johns". The information obtained was used to garner 
community support for increased enforcement against 
johns and increased drug treatment and court options 
for prostitutes. 

 In the course of a California Highway Patrol project that 
reduced deaths by 35 percent on a deadly stretch of 
rural roads, a 30-member task force spent 5 hours by 
bus inspecting 20 miles of roadway. A key 
recommendation made by the task force was to adopt a 
24-hour "headlights on" policy. 

 In a project to reduce school bullying in South Euclid, 
Ohio, police conducted focus group interviews with 
students to determine where and when they felt unsafe. 
The students identified hallways and class change-overs 
as being high-risk times and places for bullying, which 
the police confirmed by looking at school incident 
records. Based on these findings, class change-over 
times were staggered and teachers worked in teams to 
increase supervision of hallways. This led to a 60 percent 
drop of bullying in hallways. 

In her article, Karin Schmerler points out that even ad hoc 
data collection can be useful - she gives the example of a 
quick visit to a frequently targeted ATM to inspect the 
location and the lighting. In other cases, data collection 
might require the help of a local university in designing 
and conducting the exercise. 

Be Careful in Collecting Your Own Data 
Problem-oriented policing makes many demands on 
you, but it does not require you to expose yourself to 
the risk of mugging or assault. 


While you might resist collecting your own data because 
of the difficulties and time involved, it is sometimes 
essential for a problem-oriented project and it always 
brings benefits, as follows: 

1. Getting into the field can give you an understanding of 
the problem that you would never get from sitting in front 
of your computer, however rich the data that you 
manipulate. 

2. Designing a data-collection instrument can force you to 
think very hard about the nature of the problem, about 
the kind of responses that might be effective, and how 
best to evaluate your efforts. 

3. Involving police officers in data collection (and in the 
design of the exercise) provides a valuable opportunity to 
train them in the need for a rigorous, systematic approach 
in a problem-oriented project. 

4. Undertaking your own data collection gives you the 
opportunity to hone your research skills and be 
genuinely creative. 

Read More: 

Schmerler, Karin and Mary Velasco (2002). "Primary Data 
Collection: A Problem-Solving Necessity". Advanced Crime 
Mapping Topics. Denver, CO: National Law Enforcement & 
Corrections Technology Center, University of Denver. 

Tabulating Temporary Tags

Matt White and Charles Dean, working in the Charlotte-Mecklenburg Police Department, became convinced that 
many offenders were using forged temporary tags on their vehicles. These tags allowed them to operate untaxed, 
uninsured vehicles for months or even years, and made it safer for them to use their cars in committing other crimes. 
To build a case for reform of the temporary tag system, White and Dean undertook an evening's informal survey of 
two same-sized, contiguous neighborhoods in Charlotte - one high crime and the other low. The high crime area 
(Belmont on the left in the map) had 6.4 times as many reported violent offenses in the 12 months prior to the 
survey and 5.6 times as many resident arrests as the low crime area (Plaza-Millwood). As expected they spotted 12 
cars (black dots on map) with temporary tags in Belmont and none in Plaza Millwood. This was despite similar on-
street parking in both neighborhoods and a higher proportion of cars in Belmont backed into driveways to hide their 
tags from passing patrols. 
 
Source: White, Matt and Charles Dean (2004). "Abuse of Temporary License Tags in North Carolina". Understanding 
and Preventing Car Theft, Crime Prevention Studies, Volume 17, edited by Michael Maxfield and Ronald Clarke, 
Monsey, NY: Criminal Justice Press. 


22. Examine your data distributions

After collecting your data you need to know what it 
is telling you. Suppose you collected incidents of 
assaults on taxi drivers. Are assaults concentrated 
among a very few drivers? Are the assaults concentrated 
on some days of the week or times of day? 

To answer these questions you need to look at the 
distribution of the data. The figure below displays the 
distribution of homicides across Cincinnati's 53 
neighborhoods for a 36-month period. The horizontal axis 
shows the number of homicides in a neighborhood. The 
vertical axis shows how many neighborhoods had each of 
these numbers (so in the first column, 13 neighborhoods 
had zero homicides). Most neighborhoods had few 
homicides but there is a long tail stretching to the right 
where a few neighborhoods have many homicides. 

Often you need to summarize a distribution. There are 
two basic descriptions of distributions: the typical, or 
average, case and the variation, or spread of cases. 

The Average Case. The average can be calculated 
three ways: 

 Mean. This is the most common measure of 
average. The mean number of homicides in the 
Cincinnati neighborhoods is 3.7 homicides per 
neighborhood - calculated by dividing the 198 killings 
by the 53 neighborhoods. 

 Median. This is the value that divides the cases into 
two equal groups. Half the Cincinnati neighborhoods 
have two or more homicides and half have two or 
fewer. 

 Mode. This is the value possessed by the greatest
number of cases. In this example the mode is 
homicides because the biggest group of
neighborhoods have no homicides.

The Spread of Cases. There are three common 
methods to measure spread: 

 Range. This is most basic measure of spread. This is 
the lowest and highest value. In our example, the 
range is 0 to 27 homicides. 

 Inner quartile range looks at the lower and upper 
bounds of the middle 50 percent of the cases. In the 
Cincinnati example, the inner quartile range is one to 
five homicides. Half the neighborhoods fall into this 
bracket. Another 25 percent of the neighborhoods 
have one or no homicides and the last 25 percent 
have 5 or more homicides. To find the inner quartile 
range, rank the cases and divide them into four equal 
groups. The two middle groups are the innerquartiles. 
The inner quartile range is the lowest and 
the highest value of these two middle groups. 

 Standard deviation. This measure of spread 
indicates the mean difference from the mean of the 
distribution. The smaller the standard deviation, the 
smaller the average spread around the mean. The 
formula is rather tedious, but any spreadsheet or 
statistical software package can calculate it. Two 
thirds of the cases fall within one standard deviation 
on both sides of the mean. In the Cincinnati 
example, the standard deviation is 5.2 homicides. 

Bar Graph: FREQUENCY DISTRIBUTION OF HOMICIDES IN CINCINNATI NEIGHBORHOODS 
Number of Neighborhoods vs. Number of Homicides 

Range 0 to 27 homicides 
Mode=0 homicides 
Inner quartile 1 to 5 homicides 
Median=2 homicides 
Mean=3.7 homicides 
66.7% of neighborhoods within one std. deviation of mean (std. dev.=5.2) 


Which measures of typicality and spread are best depends 
on two characteristics of the data. The first is the 
symmetry of the distribution. In a symmetrical distribution, 
the shape on one side of the mean is mirrored on the 
other side. The mean equals the median in symmetrical 
distributions. If the value with the most cases is in the 
center, then the mode will be the same as the other two 
measures of average. But the mode need not equal the 
median or the mean. The distribution could have two 
modes, one on each side of the median. If the distribution 
is roughly symmetrical, the mean and standard deviation 
may be appropriate. 

If the distribution is asymmetrical, then the mean and 
standard deviation should not be used. Use the median 
or the mode and the inner quartile or full range. In 
problem analysis, asymmetry is very common. 

The second characteristic used to select measures of 
typicality and spread is the measurement scale used for 
the data. There are three common types of scales. 

 Nominal scales simply apply labels. Gender 
(male=1, female=2) is measured with a nominal scale 
because the numbers simply substitute for word 
labels, and the categories could be relabeled, male=2, 
female=1 without creating a problem. If your data is 
nominal, then only a mode is appropriate. 

 Ordinal scales rank cases as well as label them. An 
ordered list of neighborhoods, from greatest to fewest 
homicides produces an ordinal scale (first, second, 
third, through fifty-third). You cannot add and 
subtract, multiply and divide ordinal data. You can 
only determine if a case has a greater, lesser or equal 
rank to another case. If the data is ordinal, neither 
the mean nor the standard deviation can be used. 
Use the median and inner quartile range. 

 Ratio scales allow you to add, subtract, multiply and 
divide because the difference between each value is 
equal and there is a meaningful zero. The number of 
homicides in a neighborhood is measured with a ratio 
scale: the difference between 0 homicides and 1 
homicide is the same as the difference between 26 
homicides and 27 homicides, and 0 homicides has 
meaning. You can use a mean and standard 
deviation with this type of data. 

Read More: 

Help for elementary to advanced statistics with many 
useful links 
www.prndata.com/statistics_sites.htm - Hyperstat 

HyperStat Online Textbook 
http://davidmlane.com/hyperstat/index.html 

Table: TYPES OF DATA, THEIR USE, AND THEIR LIMITATIONS 
Table Headers: Nominal, Ordinal, Ratio
Row Data: 
Description: Names categories, Ranks & names categories, Has equal intervals between numbers
and zero is meaningful 

Example: 
0= not victim 
1= victim is as valid as 
0= victim
1= not victim, 

0= no crime
1= one crime
2 = more than one crime,

Number of crimes - 0,1,2,0 (0=no crimes)

Scales to the right have all the properties of those to their left, plus their own properties (e.g., anything you can do with nominal and 
ordinal data you can do with ratio data, plus more). 

Allowable Math: Same or not same, Greater lesser or equal, Addition subtraction multiplication & division 
Allowable Average: Mode, Median & Mode, Mean Median & Mode 
Allowable Spread: Range, Inner quartile range & Range, Standard deviation & Others 
Comments: Use when dealing with categories (e.g. gender) and groups (e.g. chain stores vs. not chain stores), Use when there is a natural 
ranking or order to categories (e.g., police ranks) but the differences between ranks is not always the same or unclear,  
Use for percents, counts, and a host of other measures.
 

23. Diagnose your hot spot

When mapping crime, it is helpful to distinguish 
between acute and chronic hot spots (Step 17). 
Acute hot spots show abnormal spikes in crime, 
which may decline naturally, while chronic hot spots have 
persistently higher crime levels than other areas and are 
unlikely to decline unless something is done. There are 
three basic forms of chronic hot spots, each of them 
linked to particular theories and types of responses. 

 Hot dots are locations with high crime levels. These 
show crime concentrated at facilities or at addresses of 
repeat victims (see Steps 28 and 29). Multiple crime 
events at places are represented by dots. 

 Hot lines are street segments where crime is 
concentrated. These might occur, for example, if vehicles 
parked along particular streets suffer high rates of 
break-ins. Multiple crimes along street segments are 
shown with lines. 

 Hot areas are neighborhoods where crime is 
concentrated. Hot areas arise for a variety or reasons. 
Area characteristics may give rise to crime. Or a hot area 
may contain many separate and discrete problems. On 
maps, hot areas are shown as shaded areas, contour 
lines, or gradients depicting crime levels. Jerry Ratcliffes 
hot spot typology (see box) differentiates between two 
kinds of area hot spots: 

 those that have a tightly grouped pattern of 
events and 

 those that have a relatively even spread of events over 
the hot spot area. 

The figure depicts these three forms of hot spots. 
Troublesome entertainment locations are shown as dots 
because the assaults are located at addresses. Vehicle 
break-ins, however, are along continuous street segments, 
so this concentration is shown as two intersecting lines. 
Finally, the graduated contours for the residential hot spot 
suggests that risk for break-ins is highest in one small 
area but declines as one goes away from the center. The 
dots within this graduated area depict repeat 
burglary locations. 

Clarifying the nature of your hot spot gives an inkling 
of response: 

Hot dots suggest changing the physical environment of 
particular places or changing their management. They 
also suggest intervening with high-risk victims. 
Hot lines suggest changing streets, paths and other 
routes, or the environments along them. 
Hot areas suggest large-scale partnerships to change 
neighborhoods. 

The table shows how crime concentration is related to the 
way it is mapped, and where the response is focused. 

Table: Concentration, Mapping and Action
Data:
Concentration 
Places - at specific 
addresses, corners, or 
facilities 
Victims 
Streets - along streets or 
block faces 
Area - neighborhoods 
Hot spots shown as: 
Dots 
Dots 
Lines 
Shaded areas 
Action level 
Facility, corner, address 
Victims' addresses 
Along paths, streets, and 
highways 
Neighborhoods, regions and 
other areas 
Action examples 
Closed circuit television in a 
parking garage, changing 
the way alcohol is served in 
bars. 
Helping victims prevent 
further crimes through 
target hardening. 
Creating cul-de-sacs, 
changing traffic patterns, 
altering parking regulations. 
Community partnerships, 
neighborhood 
redevelopment. 
 

Types of Hotspots 
Image of map with callout boxes.
Callout box: Hot lines representing 
thefts from vehicles along 
a side street parallel to 
an arterial route 
Callout box: One of four hot dots representing 
entertainment venues with a 
high numbers of assaults 
Callout box: One of five hot dots 
showing repeat 
burglary locations 
Callout box: A hot area represented 
as a gradient of risk for 
residential burglary 

Ratcliffe's Hot Spot Typology 
Jerry Ratcliffe differentiates among three types of hot spots. He begins with a hot spot area and then examines the 
point pattern. If all events occur at the same location then the hot spot is a "hot point." Hot points describe the 
same phenomena as hot dots. If the events are tightly grouped within the overall area, Ratcliffe calls this a 
"clustered" hot spot. Finally, if the events are spread relatively evenly across the hot spot area, he calls the hot spot 
"dispersed." Clustered and dispersed hot spots are subcategories of our category of "hot area." Ratcliffe's 
approach draws attention to the concentration of the events and requires the analyst to define the perimeter of the 
hot spot area prior to classifying the hot spot. 

Source: Ratcliffe, Jerry (2004). "The Hotspot Matrix: A Framework for the Spatio-Temporal Targeting of Crime 
Reduction". Police Practice and Research 5:5-23. 

Analysis of hot spots should begin with places, then move 
to streets, and finally to areas. Consider, for example, the 
problem of burned-out cars. Are they repeatedly found at 
specific addresses? If yes, then you should ask why these 
places are chosen instead of other nearby sites. If no, you 
should move on to examine streets. If you find street-level 
concentration, you should compare streets to find out why 
some attract burned-out cars and others do not. If there is 
little street-level concentration (i.e., crime is spread 
relatively evenly across many streets), then you should 
consider community concentration and compare high- and 
low-concentration neighborhoods. This approach assures a 
highly focused response. 

In the figure, the hot burglary dots indicate repeat victims 
within the overall neighborhood problem. An area hot 
spot alone would not reveal this. Before proceeding 
further, you should determine if the area hot spot is 
largely due to the few repeat burglary spots. You can do 
this by treating each crime location as if it had only a 
single event, and then look at the area. If it is no longer 
hot, then the problem is driven by a few hot places. If the 
area is still hot, then these repeat burglary dots are 
fragments of an area concentration of burglaries. 

Hot spot analysis can be a valuable tool early in the 
problem-solving process, but having discovered hot spots, 
you need to ask why some spots are hot and others are 
not. Stopping analysis after the discovery of hot spots 
can result in superficial analysis and the implementation 
of ineffective responses. If there is no geographical 
component to the problem, hot spot mapping has little 
utility and you must use other analytical approaches. 

Read More: 

Eck, John, Spencer Chainey, and John Cameron (2005). 
Mapping Crime: Understanding Hot Spots. Washington, 
DC: U.S. Department of Justice, National Institute 
of Justice. 


24. Know when to use high-definition maps

Conventional software is of little use when mapping 
crime in a downtown area, a college campus, a 
public housing project, or any site with many large 
buildings. This is because most buildings, however large, 
have only one street address, and crimes occurring 
anywhere in the building are assigned to that address. 
Mapping might therefore suggest that a particular 
building or facility has a crime problem, but this may only 
be because it is so large. When account is taken of the 
many people working in the building or using the facility, 
it could prove to be relatively safe. For example, George 
Rengert showed that a parking garage in central 
Philadelphia identified as an auto crime hot spot actually 
had a lower rate of auto crime than the surrounding 
streets, once account was taken of the large number of 
cars that could be parked in the facility. 

In fact, many large buildings are not safe. In his 
devastating critique of 1960s American public housing, 
Oscar Newman showed that the taller a tower block, the 
higher the rate of crime per 100 residents. He argued that 
very large blocks invited crime because residents did not 
know their neighbors and the design and layout of the 
buildings made it difficult for them to exercise any 
supervision of the public spaces, including corridors, 
elevators, and play areas. His ideas have since been 
developed into a set of principles - Crime Prevention 
through Environmental Design (CPTED) - for designing 
and laying out secure buildings and public spaces. 

To understand why a particular building is insecure, crimes 
need to be divided into specific categories and their 
locations within the building need to be charted. This is 
where high-definition or 3-D mapping comes into play. 
Unfortunately, high-definition mapping is difficult and time 
consuming. It suffers from two principal problems: 

1. 
Police records of crime rarely give the precise location 
of incidents within the building, though building 
managers or security departments can sometimes supply 
this information. When they cannot, special crime-
recording procedures may have to be established for a 
period of time in order to obtain this information 
(Step 21). 

2. For new buildings, it may be possible to obtain plans in 
digitized format, which can make mapping easier. But 
when the building is old, it may be difficult to obtain up-
to-date plans so you may have to get these drawn. 

In many cases, these problems will simply rule out high-
definition mapping, but they can be overcome, as George 
Rengert and his colleagues showed in their study of crime 
on Temple University's campus in Philadelphia. They 
developed a high-definition GIS by combining mapping 
software with AutoCAD drawings of the campus. Features 
such as water pipes and electrical wiring were eliminated, 
and the maps were altered so that streets were 
represented as lines (with lines on either side representing 
pavements), while polygons were used to represent the 
footprints of buildings and the shapes of athletic fields 
and parking lots. Shrubbery, fences, lighting, and other 
physical features were also represented on the maps. 
Crimes recorded by the campus police were then plotted 
exactly where they occurred, allowing them to be related 
to environmental features such as poor lighting or a blind 
corner allowing the attacker to lie in wait. 

Crime was mapped for the floors of each building and a 
picture of the horizontal arrangement of crime within the 
building was projected onto its ground floor footprint. 
Figure 1 shows the result for one of the buildings -
Gladfelter Hall. Crime is distributed among all floors, with 
the exception of the 10th floor. The map also shows a 
clear cluster of crime common to most floors, the area 
closest to the bank of four elevators near the center of the 
building. This is where each academic department's 
fishbowl offices for secretaries and receptionists are 
located - fishbowls because they are surrounded by glass 
windows, which allow thieves to look into them to see if 
anyone is there and if anything is worth taking. The 
Department of Criminal Justice - Rengert's own 
department - has now installed blinds, which can be 
lowered in the evenings to prevent people seeing into 
the fishbowl. 

Commercial software is already available that will produce 
photo-realistic city models, and technological 
developments, such as 3-D laser imaging, will simplify the 
production of computer maps like those of Gladfelter Hall. 
Meanwhile, when the number of incidents is small, good 
clear drawings with the location of crimes clearly indicated 
can sometimes do just as well. Figure 2 is a plan of the 
Lisson Green public housing estate in London, drawn by 
Barry Poyner, showing the locations of robberies and purse 
snatches on the walkways connecting the buildings for 
two 6-month periods: before any preventive changes were 
made and after four of the blocks were fitted with entry 


phones. In effect, the entry phones closed access to the 
walkway system from the main street entrance. In this 
case, high-definition mapping assisted with the 
assessment of preventive action. But Figure 2 also helped 
with diagnosis of the problem because it showed that 
robberies and purse snatches tended to occur on those 
parts of the walkway system that lacked surveillance from 
neighboring buildings or ground level. 

Read More: 

Crowe, Tim (1991). Crime Prevention Through 
Environmental Design. Applications of Architectural Design 
and Space Management Concepts. Boston: 
Butterworth-Heinemann. 

Rengert, George, Mark Mattson, and Kristin Henderson 
(2001). Campus Security. Situational Crime Prevention in 
High-Density Environments. Monsey, NY: Criminal 
Justice Press. 

Figure 1: 3-D Map of Gladfelter Hall, Temple University Campus 

Figure 2: Locations of Robberies and Snatches on the Walkway System on the Lisson Green Estate 
 

25. Pay attention to daily and weekly rhythms

Cycles of activities have tremendous influences on 
problems. The ebb and flow of vehicles caused by 
commuting and shopping rhythms, for example, 
changes the number of targets and guardians in parking 
facilities. This, in turn, influences when vehicle thefts and 
break-ins are most frequent. Robberies of drunken 
revelers may be more likely around bar closing time on 
Fridays and Saturdays, because the number of targets is 
higher. In this example, two important rhythms 
concentrate problem activities. The first is the 
workday/weekend cycle that makes Friday and Saturday 
nights so popular for entertainment and recreation. The 
second involves the daily cycle of opening and closing of 
bars. In this step we will discuss short-term fluctuations 
occurring over hours and days. In Step 26, we will look at 
longer time periods covering months and years. 

Different facilities have different cycles of activities that 
can contribute to their associated problems. School 
rhythms are similar though distinct from job rhythms. Bus 
stops are influenced by the rhythm of commuting and 
shopping, but also by the more frequent coming and 
going of buses. 

Charting the rhythm of crime or disorder events helps 
identify important activity cycles that may contribute to a 
problem. As shown in the figure below, calculate the 
average of the number of events occurring in each hour 
(or other time interval) over several days (data matrix at 
top), then plot the results (Chart A). Chart B shows the 
percentage of the week's events occurring on each day. 
Because some days routinely have very different rhythms 
than other days, Rachel Boba recommends charting days 
and hours together (Chart C). The result shows hot time 
periods throughout the week. Such charts are easy to 
produce; all three of these charts were created on a 
spreadsheet, using standard graphing routines. 

Temporal analysis is easiest when problem events are 
frequent. So temporal analysis will be more useful for 
common minor events, like noise complaints and minor 
traffic accidents, than for uncommon serious events, like 
murder. If there are few events, then you can look at a 
longer period to collect more events. But if the problem 
changes in the longer period, the picture that emerges 
may be distorted or out of date. 

Having reasonably exact times of occurrence helps 
temporal analysis. Contact crimes, such as robbery, rape, 
and assault, can be accurately pin-pointed as victims can 
often describe when these crimes took place. Property 
crimes, such as vehicle crimes, burglary, and vandalism, 
are much harder to pin down because victims usually 
provide only a time range during which such crimes could 
have occurred. Though it is common to use the midpoints 
in these ranges to estimate the times crimes occurred, this 
can lead to distortion and should be avoided for long 
periods (e.g., more than 8 hours). 

Jerry Ratcliffe also has identified three forms of temporal 
clustering. First, events may be relatively evenly spread 
over the entire day. He calls this a diffused pattern. 
Second, focused patterns show clustering within distinct 
time ranges. Events clustered around rush hours follow 
focused patterns. Third, acute patterns are tightly packed 
within small periods. Disturbances immediately following 
bar closing time might be an example. Focused and acute 
patterns immediately suggest temporal cycles that should 
be investigated. 

Though Ratcliffe developed his typology for daily patterns, 
the basic idea can be applied to weekly cycles. If no 
particular day of the week is routinely troublesome, this 
indicates a diffused weekly pattern. A cluster of days 
showing a marked increase in troublesome events 
indicates a focused pattern. Finally, if one or two days 
have a marked concentration of events, this indicates an 
acute pattern. 

Read More: 

Boba, Rachel (2005). Crime Analysis and Crime Mapping: 
An Introduction. Thousand Oaks, CA: Sage Publications. 

Table: Example of Number of Events by Hour and Day of Week 
Hours 
Days 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Mean 
Mon 7 3 6 9 9 11 10 17 16 17 5 6 12 7 9 5 20 18 16 8 7 10 8 7 10.1 
Tues 10 9 10 11 7 6 13 15 15 18 6 12 7 7 8 5 16 18 17 12 5 11 10 4 10.5 
Wed 4 11 12 6 8 3 18 17 24 14 10 7 4 2 4 9 23 24 24 7 5 12 3 4 10.6 
Thur 8 8 7 9 4 10 17 21 20 11 10 5 4 3 9 6 17 24 18 4 5 4 10 6 10.0 
Fri 3 12 6 7 9 12 13 19 20 19 3 4 3 4 9 3 15 16 17 8 10 18 12 13 10.6 
Sat 10 12 3 1 1 1 1 1 2 3 4 3 4 5 6 4 7 8 7 5 10 21 24 23 6.9 
Sun 21 22 10 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 3.1 
Mean 9.0 11.0 7.7 6.4 5.6 6.3 10.4 13.0 14.0 11.9 5.6 5.4 5.0 4.1 6.6 4.7 14.1 15.6 14.3 6.4 6.1 11.0 9.7 8.3 


EXAMINING TEMPORAL RHYTHMS 
Bar Graph A. Average Hourly Rhythm

Bar Graph B. Percent of Week's Events 
 
Map C. Daily and Hourly Rhythms 


26. Take account of long-term change

Is your problem getting worse or better? Does it 
fluctuate regularly or randomly? To answer these 
questions you need to study your problem by graphing 
either the number of events or a rate against time. A rate 
is typically the number of crime or disorder events divided 
by the number of targets at risk (Step 27). 

The time course of a problem can be divided into three 
basic components: 

 The overall trend, which may be obvious from visual 
inspection, and which shows whether the problem is 
getting worse, better, or staying the same over a 
long period. 

 Seasonal, daily, and weekly cycles. 

 Random fluctuations that are caused by a large 
number of minor influences. 

Systematic study of the time course of crime is called 
"time series analysis." 

Figure 1 shows homicides in Buffalo, New York. The 
straight line through the middle of the chart shows the 
overall trend. It is virtually flat, indicating very little 
upward trend (though it is increasing slightly at about 1 
homicide per 100 months). May 2001 was a particularly 
bad month, and October and November of 2000 were 
particularly low months. 

Throughout the 58 months there is considerable monthly 
variation, shown by the jagged peaks and valleys. Low 
frequency problems tend to have this characteristic, 
whereas problems with many events per time period often 
show smoother changes. These random fluctuations can 
hide systematic variation. One method for revealing a 
trend obscured by random variation is to use a moving 
average. This is called "smoothing". A 3-month moving 
average was used in this example. The July value, for 
example, is the average of June, July, and August while 
the August value is the average of July, August, and 
September. Notice that there is no data for the first and 
last months of the series because we do not have 3 
months of data for these months. Moving averages fill in 
the valleys and knock off the peaks. Longer moving 
averages produce smoother graphs than shorter ones, but 
they can also hide useful information by making the graph 
too smooth. 
 
Image of Figure 1: HOMICIDES IN BUFFALO, NY 


Cycles can be detected by comparing the same months of 
the year (or same weeks of the month, or same days of a 
week, or same hours of a day, depending on the time 
periods you are examining). It is important to note that 
months are of different lengths (and do not forget 
February in leap years) as this might influence the number 
of problem events. Some analysts use 4-week periods, 
rather than months, to address this issue. 

Obvious seasonal cycles can be seen in Figure 2. Here we 
see the number of bicycle thefts per month over 32 
months. Thefts consistently peak in July and August, and 
consistently reach their minimum in January and February. 
We can also see that on a month-to-month basis 2001 
was usually worse than 2002 and the months of 2003 for 
which we have data. This makes some sense, as there are 
more bicycles available to steal in the summer and even 
thieves have little use for bicycles in the winter (especially 
in Buffalo!). 

Separating a time series into component parts is very 
useful for revealing possible causes of a problem. The 
homicide trend, for example, could be decomposed into 
two charts showing domestic homicides and 
non-domestic homicides (or firearm and non-firearm). So 
if the non-domestic homicides were trending upward 
while domestic homicides were declining, this would 
suggest that attention should be focused on 
non-domestic homicides. 

Time series analysis is a powerful tool for evaluating the 
effectiveness of a response. The basic principle is to obtain 
a good idea of a problem's natural trends, cycles, and 
variation before the response is implemented, using the 
techniques just discussed. This tells you what you can 
expect from the problem in the future, if you did nothing 
about the problem. This provides a basis for examining 
time frames after the response. Changes in the trend, 
cycles, or even the random fluctuation suggest the 
response had an impact. The longer the time frames 
before and after, the greater the confidence you can have 
in your conclusions. 

Time series analysis can also be very complex, so if there 
is a great deal depending on a precise answer to a time 
frame analysis, it may be useful to seek the help of a 
statistician specializing in this area. 

Figure 2: SEASONAL EFFECTS IN BUFFALO BICYCLE THEFTS 


27. Know how to use rates and denominators

When one place has more crimes than another 
place, one possible reason is that one has more 
targets than another. Examining rates helps you 
understand if number of targets contributes to your 
problem (see Step 17). 

Rates describe the number of crimes per target at risk, 
during a period of time: one burglary per 1,000 
households during 2002, for example. Target rates show 
the risk the average target has of being involved in a 
crime during the time period. 

To calculate target rates you will need to: 

1. Define the type of event you are interested in (e.g., 
thefts from vehicles). 

2. Define the at-risk population (e.g., vehicles). 

3. Define the locations and time period (e.g., downtown 
area parking lots in 2004); 

4. Find sources of data that that provide counts of events 
of interest and targets for each location being 
examined (e.g., police reported crime data has 
information on address of theft, which can be 
associated with specific parking lots, and observations 
of downtown parking lots can provide estimates of the 
number of vehicles in each lot). 

5. For each location, divide the number of events (the 
numerator) by the number of targets 
(the denominator) to obtain rates. 

Defining the targets at-risk requires careful thought. If 
you are analyzing burglaries, is your target people or 
homes? "Homes" is the more reasonable answer. 
Everything being equal, if a population of a 1000 people 
lived in 500 units we would expect it to have more 
burglaries than if the same population lived in 250 units. 
If you are analyzing street robberies, then the at-risk 
population is the number of pedestrians in the area 
being examined. 

Police incident reports usually contain data describing the 
events of interest, including address information, so 
counts of events at locations can be obtained. However, 
it is often difficult to obtain information describing the 
number of targets at risk at locations. For example, 
reported thefts from vehicles may be available for parking 
lot addresses, but the number of vehicles using the lots 
may not be readily available (see box). 

To overcome this problem, you might have to find proxy 
measure of targets. The number of vehicles using parking 
lots, for example, may be proportional to lot size. Thus, a 
proxy measure for vehicles at risk might be square 
footage or number of parking spaces. The table gives 
some examples of estimating at-risk target rates. 

Proxy measures of targets must have two characteristics. 
First, they must be logically associated with the targets. 
One would expect spaces to be associated with the 
volume of vehicles, but we would not expect number of 
feet of parking lot street frontage to be associated with 
number of vehicles, because very deep lots could have 
little street frontage but contain many vehicles. Second, 
the association between the proxy and at-risk targets 
cannot vary too greatly across locations. If all parking lots 
in the downtown area are about two thirds full during the 
week, number of spaces is a useful proxy. But if some 
lots are used to capacity and others get little use, then 
number of spaces is not a good indicator of targets. 

Table: Example of Rates for Different Crimes
Type 
1. Apartment burglaries 
2. Shoplifting 
3. Motorcycle Theft 
4. Graffiti 
5. Taxi robberies 
6. Disorder calls from motels 
 
Location 
1. Apartment buildings 
2. Retail stores 
3. Neighborhood 
4. Commercial areas 
5. Company 
6. Motels 

Rate 
1. Burglaries per apartment, or per household 
2. Thefts per item on shelves, or per 
square foot of retail space 
3. Motorcycle thefts per registered 
motorcycle 
4. Graffiti per square foot 
5. Robberies per cab, or per driver, or 
driver-hours 
6. Disorder calls per guest or per room 

Comments 
1. Burglaries per resident places too much emphasis on 
large families. 
2. Thefts per customer gives an offending rate. 
3. Problematic for areas cyclists use but do not live in. 
4. Difficult to measure. 
5. Hours of exposure is preferable, but data may not be 
available. 
6. Might also look at numbers of non-guest visitors. 


Even with proxy measures, it can be difficult to obtain 
target data. Government agencies might have some of 
the information you need. For example the Hamilton 
County, Ohio, auditor has information on every land 
parcel in the county, including the square footage and 
location. Businesses and business associations sometimes 
have information about sales volume. And state supplied 
sales tax information can be used as proxy for the 
numbers of customers (when comparing stores selling 
similar items). 

Calculating rates can be very helpful in finding risky 
facilities (Step 28). Karin Schmerler and her colleagues in 
the Chula Vista, California, Police Department investigated 
calls from the city's motels. The 10 national chain and 16 
local independent motels generated similar numbers of 
calls, but the national chains contained more rooms. 

When they added up all the calls for the local 
independents and divided this by the rooms in these 
motels, Schmerler found that the average call rate for the 
independent motels was 1.8 per room. Doing the same 
for the national chains yielded a call rate of 0.5. Clearly, 
the local independents generate many more calls 
per room. 

Should you put more emphasis on high numbers or high 
rates? If your objective is to reduce the volume of crime, 
then focusing on numbers may the best choice. But if 
your objective is to reduce the chances of harm, then 
focus on rate. 

Using Rates to Identify Risky Parking Lots 

The value of calculating rates is illustrated by a project 
in Charlotte, North Carolina on which one of us 
(Clarke) worked with Herman Goldstein. Assisted by 
local analysts and police officers, we examined 
larcenies from autos (LFAs) in parking facilities in the 
downtown area of the city (locally known as Uptown). 
Hot spot analysis had shown a large undifferentiated 
cluster of these thefts centered in the middle of the 
area, but a map based on rates of theft was far more 
revealing. This map was produced by crime analyst 
Matt White, who enlisted the help of precinct officers 
in counting the number of parking spaces in each 
facility. He then calculated theft rates for each lot and 
parking garage. The resulting map revealed a much 
more detailed picture of risk. Further analysis showed 
that cars parked in lots were six times more at risk 
than ones in garages and that some lots were crime 
enablers due to inadequate security. 
Image of map with Rates of theft from cars by block, Charlotte NC, 1999 

Read More: 

Clarke, Ronald and Herman Goldstein (2003). Thefts from 
Cars in Center City Parking Facilities. From Innovation to 
Mainstream. Crime Prevention Studies, vol. 15, Monsey, 
New York: Criminal Justice Press. (available at: 
www.popcenter.org) 


28. Identify risky facilities

Facilities are environments with special functions (Step 
15). Educational facilities involve teaching and study. 
Industrial facilities produce and process materials. 
Office facilities process information. Retail facilities involve 
sales and monetary transactions. Some facilities are 
frequent sites for crime and incivilities. These include 
taverns, parks, railway stations, payphone booths, 
convenience stores, and public housing projects. These 
facilities make a disproportionately large contribution to 
crime and disorder - they are "risky facilities." 

But the term has also a more precise meaning. It refers to 
the fact that within each type of facility a few of them are 
especially risky. When we described the 80-20 rule in Step 
18, we mentioned that 5 percent of the stores in Danvers, 
Massachusetts, accounted for 50 percent of the reported 
shopliftings (see the table provided by Christopher Bruce, 
crime analyst in the Danvers Police Department). Here are 
some other documented examples of risky facilities: 

 Convenience stores. A national survey found that 6.5 
percent of convenience stores experience 65 percent of 
all robberies. 

 Gas Stations. Ten percent of Austin, Texas gas stations 
accounted for more than 50 percent of calls for driveoffs 
and drug crimes in 1998-1999. 

 Banks. Four percent of U.K. banks have rates of 
robbery four to six times higher than other banks. 

 Schools. Eight percent of Stockholm schools suffered 
50 percent of the violent crimes reported in the 19931994 
school year. 

 Bus stops. Andrew Newton's recent doctoral 
dissertation reported that 9 percent of the shelters at 
bus stops in the British city of Liverpool experienced 
more than 40 percent of the vandalism incidents. 

 Parking facilities. In another British city, Nottingham, 
just one parking deck (The Royal Moat House) 
accounted for about 25 percent (103) of the 415 crimes 
reported for all 19 downtown lots in 2001. 

There are at least eight reasons why facilities are "risky" 
and different analysis procedures can help determine 
which reasons are operating in particular circumstances: 

1. Random Variation. It is possible to get 
concentrations of crime in a few places through some 
fluke of randomness. This is more likely to occur when 
you are looking at only a few facilities with few 
incidents. Try checking the same facilities for a different 
time period. If the rank order of incidents is roughly the 
same in both periods, then the variation is not random. 

2. Reporting practices. Some facilities might always 
report crimes to the police, while others experiencing 
the same number of incidents might report many fewer 
of them. This can be difficult to check, but you should 
ask officers who are familiar with the facilities whether 
the recorded crime rates match their own perceptions of 
the crime problems in the facilities. 

3. Many targets. Some facilities contain many targets. 
The store with the most shopliftings in Danvers was one 
of the largest in the city. But this was not the whole 
story because when account is taken of its size by 
calculating shopliftings per 100 square feet (see the 
final row of the table), it is still one of the riskiest for 
shoplifting (see Step 27). 

4. Hot products. A risky facility may not have a large 
number of targets, but it might have targets that are 
particularly "hot." Store 15 in the Danvers list had the 
highest rate of shoplifting in the city per 1,000 square 
feet. This store specializes in selling small, high value 
electronic items that meet the CRAVED criteria described 
in Step 31. 

5. Location. Facilities located in high-crime areas, 
perhaps where many habitual offenders live, are more 
likely to be crime risks. This is because offenders prefer 
not to travel far to commit crime (Step 16). 

6. Repeat victimization. Some places attract people 
who are particularly vulnerable to crime. Compare the 
people being victimized in risky and non-risky facilities. 
If the re-victimization rates are different, then repeat 
victimization may be the cause of the elevated risk (Step 
29). 

7. Crime attractors. Facilities that draw in large 
numbers of offenders are crime attractors (Step 15). 
Crime attractors have high numbers of offenses and 
high offense rates. Additional diagnostic checks involve 
analysis of arrest records and other information 
containing offender names. 

8. Poor management. When owners or managers do 
not exercise proper control or management a risky 
facility can develop. The box shows how a slumlord's 
negligent management turned the properties he 
acquired into risky facilities (Step 44). 


Table: Reported Shopliftings by Store, Danvers, MA. 
October 1, 2003 to September 30, 2004

Table Headers: Store*, Shopliftings, % of Shopliftings, Cumulative % of Shopliftings, Cumulative % of Stores, Shopliftings per 1000 sq ft. 
1, 78, 26.2, 26.2, 1.3, 1.54 
2, 42, 14.1, 40.3, 2.6, 0.70 
3, 28, 9.4, 49.7, 3.8, 0.22 
4, 16, 5.4, 55.0, 5.1, 0.24 
5, 15, 5.0, 60.1, 6.4, 0.28, 
6, 12, 4.0, 64.1, 7.7, 0.31 
7, 11, 3.7, 67.8, 9.0, 0.09 
8, 11, 3.7, 71.5, 10.3, 0.16 
9, 9, 3.0, 74.5, 11.5, 0.28 
10, 2.3, 76.8, 12.8, 2.82 
11, 5, 1.7, 78.5, 14.1, 0.16 
12, 5, 1.7, 80.2, 15.4, 0.10 
13, 4, 1.3, 81.5, 16.7, 0.35 
14, 4, 1.3, 82.9, 17.9, 0.12 
15, 3, 1.0, 83.9, 19.2, 3.32 
16, 3, 1.0, 84.9, 20.5, 0.90 
17, 3, 1.0, 85.9, 21.8, 0.02 
7 stores with 2 incidents, 14, 4.7, 90.6, 30.8, 0.08 
28 stores with 1 incident, 28, 9.4, 100.0, 66.7, 0.06 
26 stores with 0 incidents, 0, 0.0, 100.0, 100.0, 0.00 
Total stores = 78, 298, 100.0, 100.0, 100.0, 0.15 
 
* The top 17 stores were (in alphabetical order): Best Buy, Boater's World, Circuit City, Costco, CVS Pharmacy, Galyan's, Home Depot, 
Kohl's, Linens & Things, Lowe's, Marshall's, Old Navy, Radio Shack, Stop & Shop, Target, and Wal-Mart 

Table: Slumlords, Crime in Low Rent Apartments and Neighborhood Blight 
Table Headers, Property, Year Acquired, # of Units, Avg Yearly Arrests Pre-Owning, Avg Yearly Arrests Post-Owning

1, 1977, 4, 0, 1.6 
2, 1982, 15, 0, 16.9 
3, 1983, 8, 0, 2.3 
4, 1985, 8, 0, 4.5 
5, 1985, 10, 0.1, 6 
6, 1986, 16, 0.2, 27.9 
7, 1986, 6/8, 8, 3.4 
8, 1987, 5, 0, 8.3 
9, 1987, 12, 0, 11.3 
10, 1988, 6, 0.4, 8.1 
11, 1991, 10, 0.2, 9.3 
12, 1991, 10+, 2.3, 21.8 
13, 1992, 4+, 1.1, 0.7 
14, 1992, 4, 0.2, 10.7 

Source: Clarke, Ronald and Gisela Bichler-Robertson (1998). "Place Managers, Slumlords and Crime in Low Rent Apartment Buildings". 
Security Journal, 11: 11-19. 

In every large city, a few low-cost rental apartment 
buildings make extraordinary demands on police time. These 
"risky facilities" are often owned by slumlords unscrupulous 
landlords who purchase properties in poor 
neighborhoods and who make a minimum investment in 
management and maintenance. Building services 
deteriorate, respectable tenants move out, and their place is 
taken by less respectable ones - drug dealers, pimps, and 
prostitutes - who can afford to pay the rent but who cannot 
pass the background checks made by more responsible 
managements. In the course of a problem-oriented policing 
project in Santa Barbara, California, Officers Kim Frylsie and 
Mike Apsland analyzed arrests made at 14 rental apartment 
buildings owned by a slumlord, before and after he had 
purchased them. The table clearly shows a large increase in 
the number of people arrested at the properties in the years 
after he acquired them. There was also some evidence that 
the increased crime and disorder in these properties spilled 
over to infect other nearby apartment buildings - a finding 
that supports the widespread belief that slumlords 
contribute to neighborhood blight. 

Read More: 

Eck, John, Ronald Clarke and Rob Guerette,
"Risky Facilities: Crime Concentration in Homogeneous
Sets of Facilities." Crime Prevention Studies, in press.


29. Be ready for repeat victimization

Some people are repeatedly victimized and, in 
conformity with the 80-20 rule (Step 18), a small 
proportion of victims account for a large proportion 
of all victimizations. Ken Pease and Graham Farrell 
carefully documented this fact in a seminal Home Office 
publication called "Once Bitten, Twice Bitten". Using 
British Crime Survey data (see the table), they showed 
that about 4% of people experience about 40% of all 
victimizations in one year. They showed that repeat 
victimization occurs for a variety of crimes including 
domestic violence, sexual assault, burglary and car-related 
thefts. They also showed that repeats occur quite quickly, 
often within a week of the first victimization, though this 
varies with the offense. 

Table: About 4 Percent of People Experience About 40 
Percent of All Crimes 
Table Headers: Number of Crimes Experienced, % of Respondents, % of Incidents 
0, 59.5, 0.0 
1, 20.3, 18.7,  
2, 9.0, 16.5,  
3, 4.5, 12.4 
4, 2.4, 8.8 
5+, 4.3, 43.5 

Source: British Crime Survey, 1992, all offenses 

Research has shown that it is easy to miss the extent of 
repeat victimization for several reasons: 

 Many victims do not report crimes to the police, which 
means that repeat victimization is undercounted in 
official police records. This is why researchers have tried 
to use surveys, in which people can be asked about 
crimes they did not report to the police. Unfortunately, 
the National Crime Victimization Survey, the United 
States equivalent to the British Crime Survey, 
undercounts repeat victimization because it uses only a 
6-month recall period and does not count all the crimes 
committed in a series against a particular victim. 

 Crime analysts often look for repeat victimization by 
counting the number of crimes at addresses, but police 
data often contains incomplete address information, 
especially for apartment units. This leads to higher 
estimates of one-time only victimizations than is actually 
the case. This difficulty is being reduced by the greater 
availability of GIS systems and through the use of 
address matching in mapping software (i.e., geocoding). 

 Repeat victimization can be underestimated because of 
the "time-window effect". If only victimizations during a 
specific time period are counted - a time window of 
January 2002 through June 2002, for example - then 
someone who had been victimized in December 2001 
and once during the six-month window would not be 
counted as a repeat victim. If they had the misfortune to 
be victimized in July 2002, we would not know that this 
person had three victimizations. Ideally, a moving 
window should be used where each new victim is 
followed for a year after the first reported event. 

In explaining repeat victimization, Ken Pease distinguishes 
two kinds of accounts: 

1. Boost accounts explain repetitions in terms of 
positive experiences at the initial offense. A burglar, for 
example, learns a great deal about a home during a 
break-in. This knowledge may encourage him to come 
back for another break-in. A burglar may also tell others 
about goods he left behind, leading to subsequent 
break-ins by other burglars. 

2. Flag accounts explain repetitions in terms of the 
unusual attractiveness or vulnerability of particular 
targets that result in their victimization by a variety of 
offenders. Some occupations have much higher 
victimization rates than others (taxi drivers, for example) 
and people who spend time in risky facilities (such as 
convenience store clerks) are also more prone to 
repeated victimization. Finally, the ownership of hot 
products, such as cars attractive to joyriders (Step 31), 
will also increase the probability of repeat victimization. 

"Lightning never strikes twice in the same place" 
Well-intentioned police officers sometimes say this to 
reassure burglary victims that they won't be victimized 
again. Unfortunately, the research reviewed here shows 
that it is not true. 

"Virtual" or "near" repeats involve victims with 
characteristics similar to the original victim or target. After 
successfully attacking the first target, offenders generalize 
to targets with similar characteristics. Houses with the 
same lay-out and in the same neighborhood as the first 
burglary, for example, can be expected to have higher 
risks because the offender has learned something about 
them from breaking in before. 


Knowledge of repeat victimization is useful for predicting 
who is most at risk and when they are at risk. This means 
that crime prevention resources can be focused on these 
people, rather than spreading resources over a number of 
people, most of whom have a very low risk of crime. 

Many police agencies now also use a "graded response" 
when dealing with repeat victims. This means that the 
more often someone has been victimized the more 
intensive the preventive action taken by the police. 
Knowing the time period between repeats also makes it 
possible to temporarily deploy crime prevention for short 
periods when the risk of crime is the greatest. For 
example, some police agencies will install temporary 
burglar alarms where the risk is high of a repeat burglary 
occurring soon. 

Read More: 

Weisel, Deborah (2004) Analyzing Repeat Victimization, 
Problem Solving Tool Series, No. 2. Washington, D.C.: 
Office of Community Oriented Policing Services, U.S. 
Department of Justice. (accessible at www.popcenter.org 
and www.cops.usdoj.gov). 

Johnson, Shane and Kate Bowers (2004). "The Burglary 
as Clue to the Future: The Beginnings of Prospective Hot-
Spotting." European Journal of Criminology, 1(2), 
237-255. 

Neighbor Beware! 
Repeat victimization tells of an elevated risk that the same victim will suffer again, most often in the immediate days 
or weeks following the preceding crime. But risk can be communicated to nearby places. Kate Bowers and Shane 
Johnson of the Jill Dando Institute of Crime Science have shown how burglary risk is communicated down a street. 
This is illustrated in the graph. A home is burgled, which we will call the reference burglary. The numbers at the 
bottom are a measure of distance from the reference burglary. A distance of one tells of a home next to a burglary 
location on the same side of the street, or the home immediately opposite. A distance of two refers to homes two 
doors down on the same side of the street, or diagonally opposite, and so on. The ordinate shows the number of 
burglaries following reference burglaries. The data come from Merseyside Police in the UK. You can see that the risk 
of another burglary declines the further the distance from the reference burglary. For any given distance, the risk is 
greater for homes on the same side of the street. This shows which homes one should seek to protect in the wake of 
a burglary. Priority should be given to homes close to the burgled home and especially on the same side of the street. 

Image of Line Graph


30. Consider repeat offending

One of the fundamental facts of criminology is that a 
small proportion of individuals commit a large 
proportion of crime. Data from Marvin Wolfgang's 
famous Philadelphia cohort study suggested that around 
5 percent of offenders account for 40 percent of crimes. 
There are two explanations for repeat offending, the first 
of which is that impulsive individuals, with weak social 
attachments to others tend to get into trouble more 
frequently than less impulsive and more attached 
individuals. The second explanation is that people exposed 
to more crime and disorder opportunities take advantage 
of them and adjust accordingly (see Step 9). Both of these 
theories can be true. Impulsive individuals with weak 
attachments require routine exposures to crime 
opportunities to become repeat offenders. 

Repeat offending can be detected by testing for the 
presence of the 80-20 rule (Step 18). This can be difficult 
in practice because offenders try to remain anonymous, so 
the data are seldom comprehensive, and may not even 
exist. Intelligence information can provide evidence of 
repeat offending, but the quality of this information is 
highly variable and seldom comprehensive about the 
offender population. We often know far more, and know 
it with greater validity, about places and victims than we 
know about offenders. Nevertheless, systematic 
interviews with offenders and their associates can reveal 
very useful information for understanding and addressing 
problems (Step 10). 

Understanding repeat offenders' objectives and motives 
can help create prevention strategies. It can make a 
difference to the solution of a vehicle theft problem if the 
thieves want to have a good time riding around in a fancy 
car, to obtain transportation home after a late night of 
partying, or to sell it for cash to support a drug habit. It 
can make a difference to the solution of a graffiti problem 
if the offenders are marking gang territories, creating 
"public art", displaying their affection, or trying to 
terrorize local residents of a different religion, race, 
or ethnicity. 

Successful offending can lead to more offending. This 
occurs in three ways: 

 Offenders, like others, learn from doing. A successful 
crime teaches important lessons. This can lead to the 
offender attacking the same target again (see box). But 
offenders, like everyone else, can generalize. So they 
learn that they may be successful if they attack similar 
targets (see Step 29). 

 Offenders learn from each other. Information can spread 
through individuals working in small groups, group 
breakup and new group formation. This underscores the 
need to understand offender networks. Police can use 
networks to spread information that enhances 
offenders' perceptions of risks or of the undesirability of 
the target or place. Part of the effort to reduce juvenile 
homicides in Boston, Massachusetts for example, 
involved highly targeted messages to gang members. 

 Successful offending can erode prevention, thus making 
subsequent offending easier. A small break in a fence, 
for example, will become larger with use. If the influx of 
offenders and offensive behaviors is faster than the 
responses of guardians and place managers, then a 
small problem will become worse. 

Catch Prolific Criminals by Focusing on Repeat Victimization 

Ken Pease has recently written about the benefits for 
detection resulting from a focus on repeat victimization. 
Evidence is accumulating that repeat victimizations are 
the work of the most committed offenders. He points out 
that this raises the intriguing possibility that offender 
targeting may be achieved simply by detecting repeated 
offenses against the same household or person, since 
these offenses are committed by offenders whom one 
would in any case wish to target. This kind of offender 
targeting avoids allegations of violations of civil liberties, 
since it focuses on the most troublesome subset of acts 
that prolific offenders commit. 

Many crime prevention techniques rest on the assumption 
of a credible threat (Step 40). Closed circuit television 
(CCTV) provides a deterrent threat to the extent that 
potential offenders believe either that someone is 
watching who will take action should they see 
misbehavior, or that offenders can be identified and 
arrested later based on CCTV recordings. This does not 
mean that there have to be many arrests, but a few well-
publicized arrests can reinforce an important message. 
And the message may be powerful if it is communicated 
through offender networks. 


When there is specific information that a few people are 
responsible for most of a problem, it can be productive to 
focus on these individuals. The Boston Police Department 
reduced homicides among young males by monitoring a 
relatively few gang members. Francis Cullen and 
colleagues suggest that probation and parole authorities 
should learn the specific circumstances under which each 
offender gets into trouble, then help offenders develop 
plans to avoid these circumstances, and finally monitor 
compliance with these plans. 

Tackling repeat offending by removing facilitating 
environments can be effective. For example, in Staining, a 
village in England, a scrap yard served as a receiver for 
stolen vehicles, parts, and other loot from thefts. Many of 
the associated offenders were known. But despite police 
enforcement efforts this problem could not be resolved. 
The local constable was able to close the site using laws 
governing pollution and other environmental hazards. This 
substantially reduced crime in the village. Similarly, police 
in the United States often use civil laws to close down 
facilities that foster drug dealing, prostitution, and other 
crimes and disorder. 

Conversely, creating crime opportunities to catch 
offenders can make things worse. In the late 1970s and 
early 1980s, a number of U.S. police departments 
experimented with "sting" operations in which they 
created fake markets for stolen goods, documented who 
sold such goods to them, and then arrested many thieves. 
A number of these operations were evaluated. There is 
no evidence that these operations reduced crime. There is 
some evidence that they may have increased crime by 
providing lucrative and convenient ways to sell stolen 
goods. Throughout this manual we have noted the strong 
influence facilitating environments can have on promoting 
criminal behavior. So one should be very cautious about 
creating artificial crime opportunities to round up 
unknown prolific offenders. 

Information from repeat offenders and their confederates 
can be used to identify features of the environment that 
facilitate offending. Much of the early crime prevention 
implemented in convenience stores was developed from 
offender interviews (Step 9). In the early 1970s, the 
Lakewood, Colorado Police Department interviewed 
convicted burglars and learned a great deal about how 
they targeted dwellings and handled stolen goods. The 
Newport News, Virginia Police Department used offender 
interviews to help analyze thefts from vehicles. An 
important piece of intelligence they gained was that 
thieves targeted vehicles that the thieves believed 
contained drugs. More recently, when the Chula Vista, 
California Police Department interviewed car thieves they 
found that the thieves had a much simpler method for 
stealing cars than investigators had suspected. This 
alerted investigators to an unknown vulnerability of older 
cars of a particular make. Such information is available 
from no other source. 

Read More: 

Cullen, Francis and colleagues (2002). "Environmental 
Corrections: A New Framework for Effective Probation and 
Parole Supervision." Federal Probation, 66 (2):28-37. 

Kennedy, David and colleagues (2001). Reducing Gun 
Violence: The Boston Gun Project's Operation Ceasefire. 
Research Report. Washington, D.C.: National Institute 
of Justice. 


31. Know the products that are CRAVED by thieves

In line with the 80-20 principle (Step 18), not all 
products are equally at risk of theft because thieves are 
very picky about what they will steal. They focus on 
relatively few "hot products," such as cars, laptop 
computers, DVD players, and cell phones. The hottest 
product of all is cash, which Marcus Felson describes as 
"the mother's milk of crime." It is the most frequently 
stolen item in larcenies, burglaries, and robberies. It fuels 
robberies of banks and off-track betting shops, attacks on 
payphones, and muggings near ATMs. 

People's possessions can help explain their victimization 
risks. For example, owning a car doubles the risk of 
becoming a crime victim, even when account is taken of 
relevant demographic and social variables. And the 
particular model of car owned can raise this risk many 
times over. To inform people about high-risk cars and to 
put pressure on manufacturers to improve security, the 
Highway Loss Data Institute in Washington, D.C. publishes 
annual data showing the number of theft-related 
insurance claims made for each model on the road. The 
table shows the five models with the highest and lowest 
theft claim frequencies (per 1,000 vehicles on the road) 
from among the 305 new models during 2001-2003. The 
Cadillac Escalade and Nissan Maxima had claim 
frequencies about 30 times higher than the five models 
with the lowest claims. Escalades were targeted for their 
custom wheels and Maximas for their high-intensity 
headlights, which also fit earlier models supplied without 
such lights. 

Useful as these data are, they do not show which cars are 
most at risk from specific forms of theft. However, 
research undertaken in the 1980s found that the models 
preferred by joyriders were "muscle" cars with powerful 
acceleration, such as the Chevrolet Camaro. Those most 
often stolen and never recovered were expensive cars 
such as Lincolns and Mercedes, and those most often 
broken into and stripped of contents were European 
models, such as Volkswagens, with good radios that fit a 
variety of models. Domestic station wagons, the staples of 
family transport, were not at risk of any form of theft. 
These were inexpensive, had terrible radios, and joyriders 
wouldn't be seen dead in them. 

Surveys undertaken by the Loss Prevention Research 
Council show that shoplifters consistently choose CDs, 
cigarettes, liquor, and fashion items such as Hilfiger jeans 
and Nike sneakers. Many of these things can readily be 
sold on the street or door-to-door in some places. Police 
have paid little attention to the fencing of stolen goods 
because it is difficult to prove and attracts relatively light 
sentences, but many departments now receive regular 
electronic reports on pawnshop transactions. Scanning 
these reports will help you keep informed about what 
burglars and others are stealing in your area. It will also 
help you think about how stolen goods are sold and ways 
of disrupting the market. 

Highest Theft Claim Frequencies, 2001-03 
Cadillac Escalade EXT (2002-03), Large luxury pickup, claim frequency 20.2 
Nissan Maxima (2002-03), Midsize 4-door car, claim frequency 17.0
Cadillac Escalade (2002-03), Large luxury SUV, claim frequency 10.2
Dodge Stratus/Chrysler Sebring, Midsize 4-door car, claim frequency 8.3
Dodge Intrepid, Large 4-door car, claim frequency 7.9
 
Lowest Theft Claim Frequencies, 2001-03  
Buick LeSabre, Large 4-door car, claim frequency 0.5  
Buick Park Avenue, Large 4-door car, claim frequency 0.5  
Ford Taurus, Large station wagon, claim frequency 0.5 
Buick Rendezvous 4WD (2002-03), Midsize SUV, claim frequency 0.7 
Saturn LW, Midsize station wagon, claim frequency 0.7
AVERAGE ALL CARS 2.5 
 
Source: Highway Loss Data Institute (www.hldi.org) 


The acronym CRAVED will help you remember which 
goods are most stolen. These are Concealable, Removable, 
Available, Valuable, Enjoyable, and Disposable: 

 Concealable. Things that can be hidden in pockets or 
bags are more vulnerable to shoplifters and other sneak 
thieves. Things that are difficult to identify or can easily 
be concealed after being stolen are also more at risk. In 
some cases, thefts may even be concealed from the 
owners of goods, as when lumber or bricks left lying 
around on building sites are stolen. 

 Removable. The fact that cars and bikes are mobile 
helps explain why they are so often stolen. Nor is it 
surprising that laptop computers are often stolen since 
these are not only desirable but also easy to carry. What 
is easy to carry depends on the kind of theft. Both 
burglars and shoplifters steal cigarettes, liquor, 
medicines, and beauty aids from supermarkets, but 
burglars take them in much larger quantities. 

 Available. Desirable objects that are widely available 
and easy to find are at higher risk. This explains why 
householders try to hide jewelry and cash from burglars. 
It also helps explain why cars become more at risk of 
theft as they get older. They become increasingly likely 
to be owned by people living in poor neighborhoods 
with less off-street parking and more offenders living 
nearby. Finally, theft waves can result from the 
availability of an attractive new product, such as the cell 
phone, which quickly establishes its own illegal market 
(see box). 

 Valuable. Thieves will generally choose the more 
expensive goods, particularly when they are stealing to 
sell. But value is not simply defined in terms of resale 
value. Thus, when stealing for their own use, juvenile 
shoplifters may select goods that confer status among 
their peers. Similarly, joyriders are more interested in a 
car's performance than its financial value. 

 Enjoyable. Hot products tend to be enjoyable things to 
own or consume, such as liquor, tobacco, and DVDs. 
Thus, residential burglars are more likely to take DVD 
players and televisions than equally valuable electronic 
goods, such as microwave ovens. This may reflect the 
pleasure-loving lifestyle of many thieves (and 
their customers). 

 Disposable. Only recently has systematic research 
begun on the relationship between hot products and 
theft markets, but it is clear that thieves will tend to 
select things that are easy to sell. This helps explain why 
batteries and disposable razors are among the most 
frequently stolen items from American drug stores. 

Read More: 

Clarke, Ronald (1999). Hot Products. Police Research 
Series. Paper 112. London: Home Office. (Accessible 
at: www.popcenter.org). 

The Rise and Fall of the Cloned Phone 
When cell phones became popular, criminals found ways to clone 
them so that they could use them without paying any bills. They used 
scanners near airports and hotels to capture the numbers that each 
phone transmits in order to send and receive calls. They then created 
"clones" of the original phones by re-programming the numbers into 
phones they had stolen. The original phone would then be charged 
for calls made by the clone. This rapidly became big business. The top 
line in the graph shows that the cloning losses for all cell phone 
companies increased quite rapidly from June 1992 to June 1996 
when they totaled nearly $450 million for the previous 6 months. 
(The losses were the charges that the phone companies wiped off the 
bills of legitimate subscribers whose phones were cloned.) At this 
point, the phone companies began to introduce a variety of 
technologies that made it much more difficult to steal phone numbers 
and to use a clone. There was a rapid reduction in cloning so that, by 
December 1999, it was all but eliminated. Incidentally, the second 
most common form of cell phone fraud, "subscription fraud" 
(opening an account with a false name and address), did not 
skyrocket when cloning was closed down, as displacement doomsters 
would predict. This could be because cloning was easy to "massproduce" 
by organized criminals, whereas subscription fraud is not. 

Image of line graph: Smei-Annual Fraud Dollar Losses United States, June 1992 - December 1999

Source: Clarke, Ronald, Rick Kemper and Laura Wyckoff (2001). 
"Controlling Cell Phone Fraud in the U.S.," Security Journal, 14:7-22. 


32. Conduct case-control studies

When analyzing a problem, it is always useful to 
ask, "why are these persons, places, times, or 
events troublesome, when other similar entities 
are far less troublesome?" Answering such questions 
requires you to compare problem cases to 
non-problem cases. 

This kind of comparison is called a "case-control study." A 
case-control study involves comparing troublesome 
persons, places, times, or events with untroublesome 
persons, places, times, or events. The troublesome cases 
are called the "cases." The cases to which they are 
compared are called the "controls." 

An example comes from data supplied by Susan Wernike, 
a crime analyst for the Shawnee, Kansas Police 
Department. For every bar in Shawnee, she calculated the 
calls per 100 persons of rated capacity. This adjusted for 
bars of various sizes (see Step 27). The figure shows the 
bars ranked from highest to lowest rate. A basic case-
control study could be applied here. The bars with the 
highest rates would be compared to those with the lowest 
rates to see if there are systematic differences in the ways 
they operate, the behaviors in the bars, and the types of 
customers they attract. 

Case-control studies are very helpful when the 
troublesome cases are rare relative to the untroublesome 
ones. This is frequently the situation in problem solving. 

To conduct a valid case-control study you should do 
the following: 

 Define your cases precisely. 

 Select a representative sample of these cases. 

 Define a group of controls that could have been 
troublesome but did not become troublesome even 
though they were exposed to similar conditions (e.g., in 
the same neighborhood or city, serve the same types of 
clients, etc.). 

 Select a representative sample of these controls. 

 Compare the characteristics of the cases to the 
characteristics of the controls. 

Substantial differences indicate characteristics that might 
be contributing to the problem. Similarities indicate 
characteristics that are probably not contributing to the 
problem. Let's explore these steps with an example. 

The simple example of Shawnee bars illustrates the first 
four steps for a very small number of locations. We can 
also examine a more complex example to point out some 
of the details of case-control studies. 

Define the cases precisely. In the early 1990s, John 
Eck was interested in why a few places were persistent 
drug dealing locations and most other nearby places were 
not. With the help of the San Diego Police Department, 
California, over 300 cases of persistent drug places were 
identified in one San Diego neighborhood. These were 
identified based on citizen calls, drug enforcement actions, 
field interrogation records, arrest data, and patrol officer 
observations. To be classified as persistent, each site 
either had to have more than one drug arrest, call, or field 
interrogation on separate days; or a warrant for a raid; or 
be identified by a patrol officer. Because multiple 
indicators were used to locate these sites, it was 
reasonable to believe that most persistent sites 
were located. 

Select a representative sample of cases that were 
troublesome. For each block in the neighborhood with 
a single dealing location, the dealing location was 
selected for study. If two dealing locations were on the 
block, both were selected. If there were more than two, 
two were randomly selected. This provided a 
representative sample of 189 locations. Selecting all the 
cases was another valid option, but that would have 
raised the costs of the study. Simple random sampling 
could also have been used, but would not have 
guaranteed coverage of all affected blocks. 

Define a group of controls that could have been 
troublesome. Controls were places in the neighborhood 
that showed no evidence of drug dealing. Nearby places 
were useful because drug sellers looking for a dealing site 
would know them. Therefore, the nearby places were 
exposed to dealers but had not been selected by dealers. 
Controls should be entities that could have been cases, 
but for mysterious reasons did not become so. The 
objective of the study is to solve the mystery. 

Select a representative sample of controls. On 
each block the same number of non-dealing places was 
selected as dealing places. These sites were randomly 
selected (as would be the case if they were in a lottery) 
from a list of places on each block that had no indicators 
of drug activity. Selecting all non-dealing locations would 
have been impractical, since there were thousands of non


dealing locations. By making sure cases and controls were 
from the same block, the selection process assured that 
the controls were exposed to drug dealers. Random 
selection assured us that the controls were representative 
of all non-dealing locations. 

Compare the cases to the controls. Observers were 
sent to the cases and the controls to record information 
about the sites. This included information on: the type of 
structure (business, apartment building, single family 
home, vacant lot, etc.); the type of street it was on 
(number of lanes, one-way/two way, etc.); the distance 
from the nearest interstate highway; the types of 
surrounding buildings; the proximity of lighting; the 
number of apartment units; the presence of fences and 
other security; adjacency to alleys and paths; and many 
other factors. The objective was to see if the dealing 
locations differed substantially from the non-dealing 
locations with regard to any of these characteristics. Two 
patterns were found, one for crack-dealing sights and the 
other for methamphetamine sites. Compared to controls, 
crack locations were more likely to be in small apartment 
buildings and have a lockable gate in a fence. Compared 
to controls, methamphetamine sites were more likely to 
be in single-family homes and adjacent to paths. The 
seeming preference of drug dealers for rental units in 
small buildings (either buildings with few apartments or 
single family homes) suggested that they were looking for 
places with low place management. In a later 
experiment, Eck found that intervening with landlords did 
reduce drug-related crime. 

Case-control studies are different from most other studies 
and require special techniques to analyze data. Step 33 
describes one technique that is particularly useful. 

Case-control studies are very useful in problem analysis. 
The approach is flexible enough to be applied to a small 
number of places (as in the Shawnee example) or a very 
large number (as in the San Diego example). Though the 
examples focused on places, the same process can be 
applied to people, times, and events. 

Read More: 

Loftin, Colin and David McDowall. (1988). "The Analysis 
of Case-Control Studies in Criminology." Journal of 
Quantitative Criminology 4:85-98. 

Graph: COMPARING HIGH AND LOW CALL RATE BARS - Shawnee, KS 

Do Not Perform an Uncontrolled Case Study
A common mistake is to collect data only on the persons, places, times, or events that are troublesome. This can 
provide misleading results because you learn only about characteristics common among the troublesome cases, but 
not if they are different from untroublesome cases. An example of this is a study conducted by the FBI in the early 
1990s to understand killings of police officers. The researchers collected information on officers killed in the line of 
duty, but did not collect information on officers who were exposed to similar conditions but not killed. 
Consequently, we do not know which, if any, of the characteristics of the dead officers contributed to their killing. 
Living officers exposed to the same conditions may share many of these same characteristics. 
 

33. Measure association

Do parking lots with gate attendants, for example, 
have fewer thefts from vehicles than parking lots 
without gate attendants? Are apartment buildings 
with on-site managers at less risk of having drug dealing 
than ones without such managers? To answer questions 
like these you will need to determine if there is a 
statistical association between some characteristic of 
persons, places or events and some measure of the 
problem (crime, injury, etc.). 

There are many ways to calculate association. Often a 
correlation coefficient is used. Correlation coefficients 
range from -1 to 1. A negative correlation means an 
increase in one characteristic is associated with a decline 
in the other (and a decline is one associated with an 
increase in the other). A positive correlation means that 
an increase in one characteristic is associated with an 
increase in the other (and a decline in one is associated 
with a decline in the other). Big coefficients mean strong 
associations (positive or negative). If a correlation 
coefficient is near zero, there is an absence of association 

- a change in one characteristic is unrelated to a change 
in the other. Any spreadsheet or statistical analysis 
program can perform the calculations. 

The Crime Analysis Unit of the Jacksonville-Duval County 
(FL) Sheriff's Department examined apartment complexes 
over 50 units. They found that for the 269 apartment 
complexes, the correlation between number of units and 
number of crimes is about .57: a modest positive 
correlation. There is a very high positive correlation (.91) 
between the number of property crimes and the number 
of violent crimes in these apartment complexes. 

You cannot use a correlation coefficient to measure 
association in a case-control study (Step 32). Instead, you 
should use an odds ratio. 

Odds ratios can be any number greater than zero. When 
an odds ratio is equal to one, there is no association 
between the characteristic and the outcome. That is, the 
risk of the outcome is the same whether or not the 
characteristic is present. If the odds ratio is between 0 
and 1, risk is higher when the characteristic is absent than 
when it is present (a negative association). An odds ratio 
of .1 indicates the risk of the outcome when the 
characteristic is present is a tenth of that when the 
characteristic is absent. If an odds ratio is greater than 1, 
the risk is higher when the characteristic is present than 
when it is absent (a positive association). An odds ratio 
of 3 means that the risk of the outcome is three times as 
large when the characteristic is present than when it 
is absent. 

To use an odds ratio both the outcome and the 
characteristic must have only two values. For example, for 
the outcome, 1 means that a bar is a high crime bar and 
0 means that it is a low crime bar. For the characteristic, 
1 means that the staff has been trained how to prevent 
assaults, and 0 means that the staff has not been so 
trained. The odds ratio would tell you whether there is an 
association between bars that have staff trained to 
prevent assaults and a bar having a great deal of crime. 
Here we would expect a negative association, so the odds 
ratio would have to be less than one to meet 
our expectations. 

Table 1 shows how to calculate an odds ratio. The 
outcome is in the row and the characteristic is in the 
column. The number of cases with the appropriate value 
for both outcome and characteristic is in each cell. Cell A 
contains the number of cases that have the characteristic 
in question. Cell C contains the number of cases without 
the characteristic. Cell B contains the number of controls 
that have the characteristic. Cell D contains the number 
of controls without the characteristic. The odds ratio can 
be computed with a hand calculator using the formula at 
the bottom of the table, but many statistical software 
packages will also calculate it. 

Table 2 illustrates the application of odds ratios in a case 
control study of drug dealing places in San Diego (see 
Step 32). The outcome is persistent cocaine or heroin 
dealing. There were 58 apartment buildings in the study 
that had indicators of persistent dealing (cases). There 
were also 47 apartments in the study that showed no 
indication of any drug dealing (controls). Does the 
presence of locked or unlocked gates or on-site managers 
influence whether a drug dealer will select the location? 
When apartments with unlocked gates were compared to 
those locked or with no gates the odds ratio was greater 
than one, but this was not significantly different from one 
(see Step 53), so we cannot rule out the possibility that 
there is no relationship between unlocked gates and drug 


dealing (recall, when an odds ratio is one, there is no 
association). The association between locked gates and 
drug dealing is significantly positive. Buildings with 
locked gates were almost three and a half times more 
likely to have cocaine or heroin dealing than other 
apartment buildings. Apartment buildings with on-site 
managers had about three-tenths the chance of becoming 
dealing sites as the apartments without on-site managers. 

This is a statistically significant negative association. 
But remember, correlation is not the same as causation. A 
correlation suggests that the characteristic in question 
might be a contributing cause, but by itself a correlation is 
insufficient to demonstrate causation. 

Table 1: Calculating Odds Ratios 
Table Headers: Outcome, Characteristic Yes(1) No(0),  Total
Yes (1) -- Cases, A C, A+C 
No (0) -- Controls, B D, B+D 
Odds Ratio = (A/B)/(C/D) = (A*B)/(C*B) 

Table 2: Apartment Building Security and Drug Dealing 
Table Headers: Unlocked Gates, Locked Gates, or No Gates, Odd Ratio
Dealing - 16, 42, 1.857
Non-Dealing - 8, 39 
Dealing - 33, 25, 3.452 
Non-Dealing - 13, 34,  
Dealing - 14, 44, 0.305 
Non-Dealing - 24, 23 


34. Look for crime facilitators

Crime facilitators help offenders commit crimes or 
acts of disorder. There are three types of facilitators: 

 Physical facilitators are things that augment offenders' 
capabilities or help to overcome prevention measures. 
Trucks extend offenders' capacity to move stolen goods, 
telephones allow people to make obscene phone calls, 
and firearms help overcome resistance to robberies. 
Some physical facilitators are tools, but others are part 
of the physical environment. Felson and colleagues 
describe how the old layout of the Port Authority Bus 
Terminal in New York facilitated a variety of crimes. 
Types of crimes had specific ecological niches created by 
the variety of design features in the old station. 

 Social facilitators stimulate crime or disorder by 
enhancing rewards from crime, legitimating excuses to 
offend, or by encouraging offending. Groups of young 
men, for example, can provide the social atmosphere 
that encourages rowdy behavior at sporting events. 
Gangs and organized criminal networks facilitate 
criminal activity by their members. 

 Chemical facilitators increase offenders' abilities to 
ignore risks or moral prohibitions. Some offenders, for 
example, drink heavily or use drugs before a crime in 
order to decrease their nervousness. 

Each type of facilitator acts against particular forms of 
situational crime prevention (Steps 39-43). This is shown 
in the table. Each facilitator (in the columns) can counter 
specific prevention methods (marked by dots). Physical 
facilitators help offenders overcome preventive measures 
that increase risk or effort. They can also act as 
provocations to deviancy. Social facilitators can offset 
each of the prevention methods. Bribes, for example, 
offset risk. Some crimes require multiple offenders to 
offset the effort. Perceptions of target desirability are 
often influenced by what is desired by others. What is an 
acceptable excuse often depends on what others will 
accept. And acquaintances can provoke crime or disorder 
through encouragement. Chemical facilitators allow 
offenders to ignore the risk and effort involved in 
committing a crime, and to make unacceptable excuses. 

Because of their capacity to blunt crime prevention, it is 
important to identify the role of facilitators in a problem. 
Evidence about facilitators can be found in investigative 
reports and from investigators, by interviewing victims and 
offenders, and by observing social situations. Analysis of 
crime reports can be used to determine the association 
between crimes and various facilitators. 

If facilitators do play a role in the problem, then the next 
step is to find the sources of the facilitators. Sources will, 
of course, vary by type of facilitator. Physical facilitators 
might be readily available, as in the case of rocks for 
rioters or public phones for drug dealers. Or they may be 
purchased legitimately, as is the case for many burglary 
tools. Or they may be stolen, as is sometimes the case 
with vehicles used in serious crimes. Once their source is 
found, it may be possible to do something about them. 
The boxes show measures taken to address the use of 
public phones in drug dealing and facilitating 
environments around cash machines. 

Table: Facilitators Used by Offenders to Counter Crime 
Table Headers: Crime prevention method, Type of facilitator used 

Measures to Prevent Use of Public Phones by 
Drug Dealers in U.S. Cities 
 
Before cell phones became widely available, drug dealers 
often relied on the use of public phones to make contact 
with suppliers and customers. Many ways to stop them 
were tried, including: 
 City ordinances to license public phones and ban them 
or limit their number at specific locations or categories 
of location. 
 Installation of rotary dials that do not permit outgoing 
calls to pagers. 
 Modification of phones to block incoming calls. 
 Community pressure on local phone companies or the 
city government to remove public phones or relocate 
them in better lit or supervised areas. 
 Permitting only operator-assisted calls or emergency 
calls during night hours by blocking coin operation of 
the phones. 
 Removal or modification of public phones by businesses 
such as convenience stores and gas stations. 
 Other types of intervention such as increased police 
patrols, warning labels on phones, and "hotlines" to 
report problems. 

Source: Natarajan, Mangai and colleagues (1996). Drug 
Dealing and Pay Phones: The Scope for Intervention. 
Security Journal 7: 245-251. 


Social facilitators depend heavily on whom offenders 
associate with, and the settings for the association. Risky 
facilities (Step 28), for example, can provide settings for 
social facilitation. Gangs provide the social support for 
crime. But even legitimate activity can on occasion spark 
social facilitation, as in the case with some politically 
motivated violence, or college student disturbances 
following games against historical rivals. 

Chemical facilitators are abundant and frequently 
associated with crime and disorder. Alcohol is particularly 
implicated as a facilitator. Various mixtures of facilitators 
are common, particularly social and chemical in 
entertainment venues. Several of the 25 techniques of 
situational crime prevention are designed to reduce the 
effect of the three kinds of crime facilitators (Steps 
39-43). 

Chart: Security Provisions for Bank Cash Machines in New York City and Los Angeles 

Source: Guerette, Rob and Ronald Clarke (2003). "Product Life Cycles and Crime Automated Teller Machines and 
Robbery." Security Journal 16: 7-18. 
 

35. Understand the crime from beginning to end

We think of crime as over in a flash. It takes just a 
few seconds to snatch a necklace in the street, 
pick a pocket, or to break into a car. And rare are 
the burglars who search every conceivable hiding place. 
Instead, they try to leave as soon as they have found 
something worth stealing - usually within a few minutes 
of entering the house. Snatching the necklace or breaking 
into the house is, in fact, just one step in a series of steps 
needed to complete each of these crimes. 

You should try to understand the sequence of steps 
involved in your crime or disorder problem. There are 
several approaches that you can follow: 

 Leslie Kennedy of Rutgers University and his colleague 
Vincent Sacco separate the steps into precursors, 
transactions, and aftermath, and have produced a 
criminology textbook, The Criminal Event, organized 
around these three stages. 

 William Haddon has developed a similar classification to 
assist thinking about road accident prevention. He 
divides preventive actions into pre-crash, crash, and post 
crash. 

 Derek Cornish uses the concept of crime "scripts" to 
guide analysis. The underlying idea is that any particular 
category of crime requires a set of standard actions to 
be performed in a particular order, just as in the script of 
a play. The scenes are the sequential stages of the 
crime; the cast consists of the criminals, victims and 
bystanders; and the tools they use are the props. 

Whichever of these approaches you use, try to list the 
sequence of steps the offender must make to complete 
the crime. The table below is Cornish's simplified 
representation of the many steps that joyriders must 
complete, but it shows that the specific act we consider to 
be the crime (in this case, taking the car) is preceded by 
preparation, and followed by escaping and enjoying the 
proceeds. This brings us to the reason for analyzing 
crimes in this careful, step-by-step manner: understanding 
clearly the sequence of actions required for the successful 
completion of the crime will reveal to you many more 
points of intervention. In other words, this will broaden 
the choice of responses for to you consider in your 
project. The final column of the table lists the possible 
responses, keyed to each stage of joyriding. 

Joyriding is one of the simpler crimes, but you can follow 
the same process of breaking the crime down into its 
constituent steps for more complex crimes as well. One 
example is crowd disturbances (including riots). Clark 
McPhail, a leading expert on crowds, created a three-step 
process for analyzing all gatherings: the assembling 
process, the assembled gathering, and the disbursal 
process. Tamara Madensen, a graduate student at the 
University of Cincinnati, added two earlier steps: initial 
planning and pre-assembly preparation. Police might 
send out warnings about hosting large drinking parties to 
forestall initial planning. To prevent bonfires, easily 
burnable trash should be removed during the pre-
assembly preparations. Police might greet arriving 
students to encourage lawful behavior during the 
assembling process. When the crowd is assembled, police 
can monitor behavior and intervene if trouble develops. 
During the disbursement process, police want to make 
sure the crowd breaks up quickly and peacefully. 

Table: Steps in Joyriding and Associated Responses
Table Headers: Stages, Steps, Responses
Row Data:
STAGES
1. Preparation 
2. Entering setting 
3. Enabling conditions 
4. Selecting target 
5. Completing the theft 
6. Exiting the setting 
7. Aftermath 

STEPS 
1. Get tools (e.g., screwdriver, duplicate keys, slide-
hammer, short steel tube) 
Select co-offender 
2. Enter parking lot 
3. Loiter unobtrusively 
4. Reject alarmed cars 
Choose suitable vehicle 
5. Enter car (duplicate keys, use screwdriver) 
Break ignition lock (tube or slide-hammer) 
Hot wire ignition and start car 
6. Leave parking lot 
7. Use car to joyride 
Abandon car on wasteland 
Set fire to car 

RESPONSES 
1. Control sales of equipment such as hand scanners and 
duplicate keys 
2. Parking lot barriers; attendants; few entrances 
3. CCTV and/or regular patrols to deter loiterers 
4. Visible protection of tempting vehicles 
5. CCTV to monitor suspicious behavior; improve natural 
surveillance of lot; vehicle alarm to alert security; 
vehicle immobilizer 
6. Attendants or other exit barriers 
7. Vehicle-tracking system activated; vehicle curfew 
program; surveillance of dumping sites 
 
Source: Cornish, Derek (1994). "The Procedural Analysis of Offending and its Relevance for Situational Prevention." Crime Prevention Studies, 
volume 3. Monsey, NY: Criminal Justice Press 

Preventing Deaths of Illegal Migrants 

In an unusual application of situational prevention, Rob 
Guerette of Florida International University, has 
undertaken a careful study for the U.S. Border Patrol of 
the circumstances in which illegal migrants die crossing 
the U.S.-Mexico border. Each year, some 300 migrants die 
in tragic circumstances - for example, by drowning in 
canals and rivers, by heat exposure in desert regions, or as 
result of vehicle accidents. By tracing the steps that add 
the illegal migrants take in crossing the border and trying 
to understand the circumstances that lead to loss of life, 
he came up with a number of life-saving suggestions. He 
classified these suggestions in a two-way grid: 

 Across the top, he followed William Haddon's method 
and sorted the preventive suggestions into those that 
applied before, during, and after the life-threatening 
event. 

 Down the side of the grid, he followed the crime triangle 
and sorted measures by whether they were aimed at (1) 
the migrant or the "victim," (2) the "coyote," who is 
employed by migrants to get them safely across the 
border (the "offender"), and (3) the "place" or 
environment, i.e., desert, rivers, urban areas, and 
so forth. 

Some of these suggestions were extensions or 
improvements of measures already in place, but others 
were novel, which shows the value of his approach. Most 
of the suggestions are self-explanatory, but more 
background is needed to understand some of them (the 
numbering follows the table): 

1. His research showed that proportionately more females 
die from heat exposure. 

3. Migrants typically gather in staging towns close to the 
border in Mexico where they make contact 
with "coyotes." 

4. When highly trained search and rescue agents are 
dispatched to make a rescue, Guerette found migrants 
are more likely to survive than when regular line agents 
are dispatched. 

5. To prevent immediate attempts to re-cross the desert in 
the very hot months, migrants apprehended at these 
times in the Arizona desert were laterally repatriated in 
2003 to Mexican towns near the Texas border. This 
experiment was effective in saving lives. 

6. In 2004, the Mexican authorities agreed to accept 
repatriations from Arizona to destinations in the interior 
of Mexico. 

14. Motorists in Arizona commonly see small bands of 
illegal migrants attempting to cross the desert in the hot 
months. This campaign would seek their aid in saving 
lives by calling a 1-800 number to report the sighting. 

15. Border Patrol agents in Arizona told Guerette that 
they often had great difficulty in locating a migrant 
reported to be in distress by other migrants, whom they 
had apprehended. This is because large swathes of the 
desert are quite featureless and the directions given by 
apprehended migrants are often vague. A systematic 
program of temporary desert markings using color-
coding or symbols could ameliorate this difficulty. 

Table:
Table Headers: Before life threatening event, During life threatening event, After life threatening event 

Before Life Threatening Event:
Migrant 
1. Inform female migrants 
about dangers of crossing 
the desert 
2. Implement alert system for 
hazardous conditions 
Coyote
7. Implement alert system for 
hazardous conditions 
8. Warn coyotes of 
prosecution in event of 
migrant deaths
Environment
11. Target problematic times 
and places 
12. Erect barricades at 
dangerous crossing points 
13. Post visible warning signs 
in risky areas 

During Life Threatening Event
Migrant
3. Distribute instructions in 
staging towns for migrants 
to follow when in distress 
4. Expand Border Patrol 
search and rescue capacity 
Coyote  
9. Target coyote for arrest
Environment
14. "Save a life/report a 
migrant" publicity 
campaign 
15. Desert markers

After lift threatening event
Migrant
5. Lateral repatriation 
6. Interior repatriation 
Coyote
10. Create task force to 
prosecute coyotes when 
deaths occur 
Environment
16. Continually review data 
to detect new patterns of 
hazard 


36. Be sure to answer the five "W" (and one "H") questions

When you have completed your analysis using the 
concepts discussed in the previous steps, you 
should ask whether it meets the test of a good 
newspaper story. Does it adequately answer the 5 W and 
one H questions: what, where, when, who, why, 
and how? 

These same questions structure Barry Poyner's method of 
crime analysis by breaking up a larger problem into its 
constituent parts. For example, when he was asked by the 
Home Office to study "street attacks" in downtown 
Coventry and Birmingham (two large cities in England), he 
found that the police classified these as robberies and 
thefts from the person, but he found that the majority of 
incidents fell into a number of quite distinct problems: 

 Robbery from street vending booths 
 Robbery of drunks 
 Money snatched while being taken to the bank 
 Snatching women's purses 
 Wallets/money snatched from the victim's hand after a 
verbal ploy 
 Thefts from shopping bags 
 Pickpocketing at bus stops 

This was a much more meaningful characterization of 
"street attacks" and was an important first step in 
understanding the events. He then began to sort through 
the incident reports, trying to arrive at a picture of each 
problem that would help him find a response. 

Incident reports are quite variable in the information 
recorded, especially when the victim is not present and 
there are no witnesses. However, Poyner tries to piece the 
reports together to get a picture of the particular problem 
(see box). For each incident he tries to discover: 

 What happened? This entails spelling out the 
sequence of events and the actions of those involved 
(Step 35). 

 Where did it happen? Sometimes the sequence of 
events takes place in several locations. For example, a 
car might be stolen from a parking lot, moved to a 
garage for stripping of valuable parts, and then dumped 
on a piece of wasteland. Information may only be 
available about the first and last locations. Visiting these 
can help explain why the offender selected them. 

 When did it happen? Householders or car owners 
might know only that their car was stolen or their house 
burgled "sometime during the weekend." For many 
interpersonal crimes, however, the victim will be able to 
report precisely when the crime occurred, which may 
permit inferences about such matters as whether the 
streets were deserted. 

 Who was involved? There is always at least one 
offender; there may be one or more victims even if they 
have no direct contact with the offender; there may be 
witnesses and other third parties. Statements in police 
records made by witnesses and victims can provide 
much useful information, but it might sometimes be 
important to question a sample about the event. 

 Why did they act as they did? It is important to 
understand the specific benefits that a particular kind of 
crime brings to the offender. In many cases of theft, the 
motive will be obvious, but for interpersonal crimes and 
for vandalism the motives may only emerge from 
interviewing offenders (Step 10). Equally important for 
prevention may be to understand why victims and 
witnesses behaved as they did and to answer such 
questions as "What causes some victims to respond by 
attacking the offender?" and "Why do witnesses often 
fail to intervene?" 

 How did the offender carry out the crime? Crime 
can be thought of as a process, with several steps from 
initiation to completion, rather than a circumscribed act 
occurring at a specific point in time. At each step the 
offender must make decisions, might need to work with 
others, and might need to employ specific knowledge 
and tools. This is essentially the idea underlying 
Cornish's "script" approach discussed in Step 35. It may 
not always be possible to develop detailed scripts, but 
the analysis should give a clear picture of how the crime 
was accomplished. 

Poyner's analysis of pickpocketing at bus stops illustrates 
the approach. He was able to construct a detailed 
description of the crime by supplementing the rather 
sketchy incident report with observations of the lines 
waiting for the bus. He found that the peak time for 
pickpocketing was the afternoon rush hour, particularly on 
Fridays when lines were long. Groups of three or four 
youths would hang about near the lines, looking in the 


windows of nearby stores to avoid arousing suspicion, 
while watching at the same time for suitable victims. 
These were invariably middle-aged or older men who kept 
their wallets in the back pockets of their trousers. 
(Younger men wore tighter-fitting trousers and did not 
keep their wallets in their back pockets.) 

As their victims began to board the bus, which used a 
pay-as-you-enter system, the youths would run to the 
front of the line, jump on the boarding platform of the 
bus and jostle the riders. They would ask the driver some 
irrelevant question about the destination of the bus. 
Meanwhile one of the youths would pick the pocket of 
the victim. The victim would be irate at being jostled and 
would not realize what was happening. The driver would 
shout at the youths to get off his bus and other 
passengers would be complaining. The youths would step 
off the bus and slip away into the crowd. The youths were 
never caught. The victim would only find out later that 
his wallet was gone. 

This analysis suggested four possible responses: 

 Instead of pay-as-you-enter, tickets might be sold in 
advance for use at these stops. 

 Bus stops might be re-sited away from main pavements 
and organized in bays more like a bus station. This 
would make it difficult for offenders to lie in wait. 

 Use a bus shelter to screen the waiting lines so the 
offenders would be unable to identify potential victims 
in advance. 

 Construct line-marshalling barriers at the boarding point 
so offenders could not jump onto the bus platform. 

Note that all these solutions are outside the normal remit 
of the police. Officers rarely consider that their role 
involves, for example, redesigning bus stops. But as a 
problem-solving crime analyst your job is to cut crime, and 
you may need gently to persuade police colleagues that, 
in the widest sense, it is their job, too. 

Working Like an Archaeologist
"There is a further advantage of combining incidents. In some cases we may have much less detail 
than other cases but otherwise the facts we do know about are the same. It may be possible to 
reconstruct the missing data in these less well reported incidents in much the same way as the 
archaeologist reconstructs broken pottery from an excavation. He may only have a few pieces of the 
broken pot but from knowledge of other similar pots he can be reasonably sure about the form of the 
whole pot. This archaeological approach is quite helpful when, for example, we may have some 
detailed accounts of what offenders do in a few cases where they have been caught. It seems 
reasonable to believe that similar behaviour occurred in similar crimes even though the offenders 
were not caught." 
 
Source: Poyner, Barry (1986). "A Model for Action." Situational Crime Prevention, Gloria Laycock and 
Kevin Heal. London: Her Majesty's Stationery Office. 


37. Know that to err is human

Crime prevention often involves predictions. Will 
offenders associated with the problem continue to 
offend as they have done in the past? Will recent 
victims become victims again in the near future? Will hot 
spot places become cold spots, or will they stay hot? 
Though past behavior may be our best predictor of future 
behavior, it is not a perfect predictor. 

The examples above deal with predicting the future. But 
we also try to probe the unknown in other ways, including 
in our responses to problems. A polygraph examiner tries 
to assess whether the subject is lying or not. Drug tests 
are used to determine if people have recently used illicit 
drugs. Metal detectors and baggage screening devices at 
airports are used to determine if passengers have 
weapons on their person or in their luggage. In all these 
examples the examiner is trying to draw a conclusion 
about an unknown condition. And just like predictions of 
the future, the examiner may make an accurate 
assessment or an inaccurate one. Consequently, it is very 
important to understand how predictions and other 
judgments can fail. 

A useful way to examine errors of prediction and 
judgment is to compare the prediction to what actually 
occurs. The columns in Table 1 show two possible 
predictions: Yes, the outcome will occur; and No, the 
outcome will not occur. The rows show two actual 
outcomes: Yes, the outcome did occur; and No, the 
outcome did not occur. 

Table 1: Types of Prediction Errors
Table Headers: Actual Outcome, Yes, No
Actual Outcome 
YES, A. Accurate True Positives, B. False Negatives   
NO, C. False Positives, D. Accurate True Negatives  
Accuracy Rate (A+D)/(A+B+C+D)
False Negative Rate B/(A+B+C+D)
False Positive Rate C/(A+B+C+D) 
 

Imagine a large number of predictions. When a prediction 
corresponds to the actual, then it is accurate. Cells A and 
D contain counts of accurate predictions. You can 
calculate an accuracy rate by adding the number of 
predictions that fall into these two categories and dividing 
by all the predictions made. 

Lets look at cells B and C. When the decision-maker 
predicts that the outcome will not occur, but it does occur 
then it goes into cell B. This is called a False Positive. 
Cases in cell C represent situations in which the decision-
maker has predicted that the outcome would occur, but it 
did not. These are False Negatives. You can calculate 
error rates for both types by dividing the number of 
predictions in each cell by the total number of predictions. 

Lets look at a hypothetical example. To curb crime in 
rental housing, a police department facilitates and 
encourages landlords to conduct background checks. 
Prospective renters with recent histories of criminal 
behavior are not accepted. Such a policy implies a 
prediction that people with recent histories of criminal 
involvement will continue that involvement on or nearby 
the rental property and that people without such 
backgrounds will not engage in this type of behavior. 
Even advocates of such a policy would agree that such 
predictions are not perfect, but it would be useful to know 
two things. First, does such a policy reduce rental 
property crime? An evaluation could answer this 
question. But even if it does reduce crime, what are the 
negative consequences? To answer this question requires 
an analysis of the prediction errors. 

If we were able to collect the relevant data we might be 
able to create a table like Table 2. We see that the 
policy's predictions are accurate. But how do we feel 
about the errors? Should something be done about 
people without a recent history of prior criminal 
involvement who commit crimes? Are too many former 
offenders who are not engaging in criminal behavior 
being denied housing? 

Table 2: Example of Prediction Error Analysis 
Table Headers: Later Criminal Involvement, Prior Criminal Involvement - Yes or No, Total  
Row Data:
YES, 35, 10, 45 
NO, 35, 496, 531 
Total, 70, 506, 576

Accuracy Rate 92.2% 
False Negative Rate 1.7% 
False Positive Rate 6.1% 


Tighter restrictions to curb offending by people who have 
no recent criminal record might reduce the false negative 
rate, but it could increase the false positive rate, 
particularly if the information for making the decisions is 
less accurate than the information currently used. On the 
other hand, making distinctions among applicants with a 
recent criminal history could decrease the false positive 
rate, but at the expense of increasing the false negative 
rate. Such tradeoffs are quite common. 

Further, we may regret one type of error more than 
another. If the types of crimes being prevented by the 
landlords are relatively minor, then the false positive rate 
might be too high. But if these are crimes of serious 
violence being averted, then the false negative rate may 
be of greater concern. The consequences of the errors are 
very important and people often disagree over these. 

Another source of disagreement are the error rates 
themselves. Such rates are often very difficult to estimate. 
Consider the shaded boxes in Table 2. Under most 
circumstances, these figures will be unknown. The 
landlords might count how many people they turned away 
because of a criminal record, but they cannot tell us what 
such people would do if they had not been turned away. 
In other situations the shoe is on the other foot; false 
positives may be known with some precision, but false 
negatives are unknown. In airport screening, false 
positives are known because predictions of having 
contraband are followed by closer scrutiny. A passenger 
who security personnel believe is carrying a firearm will 
be subject to a very careful search, thus revealing if the 
initial prediction was accurate or inaccurate. However, 
false negatives are not known with much reliability. A 
passenger, who carries contraband past airport security 
may not be checked again, So we cannot learn that she 
was a false negative. 

In some circumstances it is possible to use a pilot test to 
accurately estimate the errors by making the predictions, 
not acting on them, and carefully observing what 
happens. This might be difficult to do with offenders, who 
prefer to keep their misdeeds hidden, but it could work 
with potential victims or crime places. For example, a 
response to a problem might involve predicting which 
places are most likely to be crime sites and then 
intervening at those locations. Prior to implementing this 
response, a pilot study could be conducted in which the 
predictions are made, but no action is taken. If the error 
rates are unacceptably high, then it might not be worth 
implementing the response. 


38. Embrace your key role at response

The first inclination of police, even when they have 
been involved in a detailed analysis of a problem, is 
to try to solve it by beefing up enforcement. You 
should expect this and not oppose it, even if the impact is 
usually short-lived. But from the beginning you should be 
helping your police colleagues find more permanent 
solutions. Local community partners could provide this 
help, but instead they often promote their own agendas 
and push solutions with limited impact. The result is often 
a compromise package of measures, none of which is 
effective, but each of which may satisfy one or other of 
the parties. In fact, the disagreements over solutions may 
lead to a loss of momentum and nothing may be 
properly implemented. 

You can help to stop this from happening, but you must 
first become an expert on solutions. For example, if the 
problem is one of car theft, you must be able to speak 
authoritatively about the ineffectiveness of decoy vehicles 
or "lock your car" campaigns. If it is a burglary problem, 
you must know the results of research on burglar alarms 
or improved street lighting, both of which may be 
suggested as solutions. You should also be thoroughly 
familiar with findings on displacement, since innovative 
solutions are often blocked by knee-jerk invocations of 
this theory. 

To become an expert on solutions you must know how to 
find out more about particular responses by undertaking 
rapid literature searches (Step 19). You must also become 
an expert on situational crime prevention, the science of 
reducing opportunities for crime. Situational prevention 
uses the same action-research methodology as problem-
oriented policing and has dozens of evaluated successes 
to its credit. Much of the knowledge about displacement, 
diffusion of benefits, repeat victimization, and many other 
concepts discussed in this manual have been developed 
by situational prevention researchers. The next five steps 
discuss the 25 techniques of situational crime prevention, 
which fall into five main groups (see box). These are 
defined by what Nick Tilley of the University of 
Nottingham Trent in the U.K. calls the mechanism through 
which the techniques achieve their preventive effect: 
increasing the effort of crime, increasing the risks, 
reducing the rewards, reducing provocations and 
removing excuses. 

At this point, you might be asking yourself why you 
should assume this responsibility for identifying solutions. 
Isn't it enough that you carry most of the burden at the 
scanning, analysis, and assessment stages? And even if 
you did take on this role, why should anyone pay 
attention to you? But to become a problem-solving 
analyst you must go beyond your traditional analytic 
function. You must become a full and equal member of 
the problem-solving team. You may be relatively junior, 
but your authority comes from your expert knowledge, not 
your position. People will listen if you make novel 
suggestions, or if you provide supporting evidence for 
other people's good ideas. 

Table: Twenty-Five Techniques of Situational Crime Prevention 
 
Increase The Effort
1. Target harden 
2. Control access to facilities 
3. Screen exits 
4. Deflect offenders 
5. Control tools/weapons 

Increase The Risks
6. Extend guardianship 
7. Assist natural surveillance 
8. Reduce anonymity 
9. Use place managers 
10. Strengthen formal surveillance 

Reduce The Rewards
11. Conceal targets 
12. Remove targets 
13. Identify property 
14. Disrupt markets 
15. Deny benefits 

Reduce Provocations
16. Reduce frustrations and stress 
17. Avoid disputes 
18. Reduce arousal and temptation 
19. Neutralize peer pressure 
20. Discourage imitation 

Remove Excuses
21. Set rules 
22. Post instructions 
23. Alert conscience 
24. Assist compliance 
25. Control drugs and alcohol 


Table: Seven Criticisms of Situational Crime Prevention - and Rebuttals 

Criticism 
1. It is simplistic and atheoretical. 
Rebuttal
It is based on three crime opportunity theories: routine 
activity, crime pattern, and rational choice. It also draws 
on social psychology. 

Criticism 
2. It has not been shown to work; it displaces crime 
and often makes it worse. 
Rebuttal 
Many dozens of case studies show that it can reduce 
crime, usually with little displacement. 

Criticism
3. It diverts attention from the root causes of crime. 
Rebuttal
It achieves immediate results and allows time for finding 
longer-term solutions to crime. 

Criticism
4. It is a conservative, managerial approach to the 
crime problem. 
Rebuttal
It promises no more than it can deliver. It requires that 
solutions be economic and socially acceptable. 

Criticism
5. It promotes a selfish, exclusionary society.
Rebuttal
It provides as much protection to the poor as to the rich. 

Criticism 
6. It promotes Big Brother and restricts 
personal freedoms. 
Rebuttal
The democratic process protects society from these 
dangers. People are willing to endure inconvenience and 
small infringements of liberty when these protect them 
from crime.

Criticism
7. It blames the victim. 
Rebuttal 
It empowers victims by providing them with information 
about crime risks and how to avoid them. 
 

You should always opt for solutions that could bring a 
rapid reduction in the problem. This means that you must 
focus on the immediate, direct causes of a problem rather 
than the more distant, indirect ones. This important 
distinction has been developed by Paul Ekblom of the 
Home Office, and can be illustrated by the problem of bar 
fight injuries caused by broken bottles and glasses. 
Distant "root" causes might include racial discrimination 
producing a generation of disaffected minority youths, 
lack of local employment opportunities resulting in widespread 
social exclusion, and the premium placed on a 
"tough" reputation in a deprived and lawless community. 
More immediate, situational causes might include 
irresponsible serving practices promoting drunkenness in 
local bars and taverns, and the immediate availability of 
bottles and glasses that can easily be used as 
deadly weapons. 

Rapid and sustained reductions in crime can only result 
from addressing situational causes; addressing root 
causes, even if we knew what to do about them, can only 
pay off in the comparatively distant future - long after the 
current stakeholders have any remaining interest in the 
problem. Meanwhile, unless the immediate causes are 
dealt with, broken glasses and bottles will continue to 
claim victims. 

Some situational solutions can also take a long time to 
implement. For example, the danger posed by glasses and 
bottles could be addressed by legislation requiring bars 
and taverns to use only toughened glasses and bottles 
that disintegrate into crumbs when broken. This would 
probably take years to accomplish. Much more realistic 
would be to bring community pressure to bear on local 
taverns to serve beer only in toughened or plastic glasses 
and to refuse to sell bottles at the bar. This ought to be 
achievable in a much shorter time. You might have a 
particular analytic role in promoting this solution by 
assembling data about the likely costs for the pubs and 
the reduced costs of injuries and emergency care. In fact, 
it will probably fall to you (who else?) to collect data 
about the feasibility, costs and the public acceptability of 
any of the measures that are being seriously considered 
by the problem-solving partnership. 

The bottom line is that you must acquire knowledge of a 
broad range of solutions, and be prepared to fight for 
good ideas, if your careful analytic work is to bear fruit. 

Read More: 

Clarke, Ronald (1997). Situational Crime Prevention: 
Successful Case Studies (2nd ed.). Monsey, NY: Criminal 
Justice Press. 

Von Hirsch, Andrew, David Garland and Alison Wakefield 
(2000). Ethical and Social Perspectives on Situational 
Crime Prevention. Oxford: Hart Publishing. 


39. Increase the effort of crime

Here we describe the most basic category of 
situational measures - those designed to increase 
the difficulties of crime - beginning with target 
hardening. Situational prevention is sometimes dismissed 
as being nothing more than this, though it is only one of 
the 25 techniques that the approach encompasses. Note 
that there is considerable overlap between the techniques. 
For example, target hardening makes crime more difficult, 
but it can also slow up offenders and increase their 
chances of getting caught. Some measures can also serve 
more than one purpose. When using this classification, do 
not spend time worrying where a particular measure fits use 
it only to ensure that you consider the widest possible 
repertoire of situational responses to a particular problem. 

Harden targets. An obvious, often highly effective way 
to obstruct the vandal or the thief is through physical 
barriers such as locks, screens, or reinforced materials. The 
introduction more than 30 years ago of steering locks in 
this country and overseas brought about long-term 
reductions in car theft, and ignition immobilizers are now 
reinforcing these benefits. Anti-robbery screens in London 
post offices have reduced robberies by 40 percent and 
bullet-resistant passenger screens have cost-effectively 
reduced assaults and robberies committed against cab 
drivers in New York City (see Robbery of Taxi Drivers, 
Problem-Oriented Guides for Police No. 27, accessible at 
www.cops.usdoj.gov and www.popcenter.org). 

Control access to facilities. Keeping people out of 
places they have no right to be, such as military camps, 
factories, and apartment blocks, has a long pedigree think 
only of the portcullises, moats, and drawbridges of 
medieval castles. It is also a central component of Oscar 
Newman's concept of defensible space, arguably the start 
of scientific interest in situational prevention. Barry Poyner 
has demonstrated that the installation of entry phones 
and the demolition of walkways linking buildings 
significantly reduced muggings at a London estate (Step 
24). In some cases, access controls are intended to ensure 
the possession of tickets and documents. The redesign of 
tickets to make them easier to check produced a sharp 
reduction in fare evasion on Vancouver, Canada ferries. In 
the most famous example, baggage and passenger 
screening at airports in the early 1970s contributed to a 
reduction in the number of airline hijackings worldwide 
from about 70 to 15 per year. 

Screen exits. The purpose of exit screening is to ensure 
that those leaving a building, a facility, or some other 
place have not stolen anything or have paid all fees and 
taxes. Passengers on the Washington, D.C. subway must 
insert their tickets in the automatic gates not only when 
entering the subway, but also on leaving. This provides 
two opportunities to check that the fare has been paid. 
On the New York City subway, passengers must insert 
their tickets in the gates only once, when entering the 
subway, thus reducing the chances of detecting fare 
evasion. Other examples of exit screening include border 
controls on leaving a country and the use of electronic 
tags in library books and merchandise. These tags activate 
an alarm if books have not been checked out or if a thief 
tries to remove a tagged item from the store. Studies have 
shown that they significantly reduce shoplifting and theft 
of library books. 

Deflect offenders. Rival groups of soccer fans in the 

U.K. are segregated in the stadium to reduce fighting, and 
their arrival and departure is scheduled to avoid the 
waiting periods that promote trouble. Scheduling the last 
bus to leave immediately after pub closing time is 
intended to interfere with another of Britain's less 
admirable traditions, the closing time brawl. These are 
examples of deflecting offenders away from crime targets, 
a situational technique suggested by routine activity 
theory. Other examples are provided by road closure 
schemes that have produced reductions in many kinds of 
crime (see Closing Streets and Alleys to Reduce Crime, 
Problem-Oriented Guides for Police, Response Guide No.2, 
accessible at www.cops.usdoj.gov and 
www.popcenter.org). Even drive-by shootings in Los 
Angeles have been reduced by street closures (see box). 

Table: Increase The Effort Of Crime

Harden targets 
 Steering column locks and ignition immobilisers 
 Anti-robbery screens in banks and post offices 
 Bullet-resistant shields for cab drivers 
Control access to facilities 
 Entry phones for apartment complexes 
 Electronic card access to garages and offices 
 Defensible space designs for public housing 
Screen exits 
 Ticket needed to exit 
 Export documents 
 Electronic tags for stores and libraries 
Deflect offenders 
 Separation of rival fans in stadium 
 Street closures 
 Separate bathrooms for women 
Control tools and weapons 
 Safer guns 
 Toughened beer glasses 
 Stop incoming payphone calls to foil drug dealers 
 Photos on credit cards and thumbprints on checks 
 

Control tools and weapons. Saloons in the Wild West 
routinely required customers to surrender their pistols on 
entry because of the risk of drunken gunfights. More 
recently, so-called "safer" handguns have been developed 
that can only be fired by the owner or which shoot wax 
bullets or tranquilizers. To prevent glasses being used as 
weapons when broken, many pubs in the U.K. now use 
"toughened" beer glasses. The first commercial use of 
Caller-ID (in New Jersey at the end of the 1980s) 
produced a 25 percent reduction in obscene telephone 
calls. Step 34 lists the different ways in which cities have 
attempted to control the use of public phones in drug 
dealing, including blocks on incoming calls and banning 
them from specific locations. Re-programming of public 
phones at the Manhattan bus terminal prevented illegal 
access to international phone service, thus wiping out a 
multi-million dollar scam perpetrated by hustlers. 
Improved security procedures for delivering credit cards 
produced a substantial drop in credit card frauds in this 
country in the mid-1990s (Step 11). 

A Designer Solution to Drive-by Shootings 

Rival gangs often settle disputes by shooting at 
members of the other gang from moving cars. These 
"drive-by shootings" are difficult to prevent through 
youth work or by intensified policing. A novel solution, 
Operation Cul de Sac, was tried in one 10-block area in 
Los Angeles, which had experienced the city's highest 
level of drive-by shootings and gang homicides. The 
police installed traffic barriers on the most affected 
streets. These dead-end streets prevented cars from 
entering at one end and required those that did enter at 
the other end to return the same way. This not only 
made it more difficult for shooters, but also increased 
their risks because when they returned the same way, 
their targets could have their own guns ready. 
The barriers brought about an immediate reduction in 
drive-by shootings and homicides. In the year before 
Operation Cul de Sac, 1989, seven homicides were 
committed in the area. In the 2 subsequent years, after 
the barriers were installed, only one homicide was 
recorded. There was no evidence that homicides had 
been displaced to another neighbourhood. At the 
conclusion of Operation Cul de Sac, when the barriers 
were removed, homicides increased again to their 
previous level. 
Source: Lasley, James (1998) "Designing Out" Gang 
Homicides and Street Assaults. Research in Brief, National 
Institute of Justice. Washington, D.C.: U.S. Department of 
Justice. 


40. Increase the risks of crime

According to interviews with offenders, they worry 
more about the risks of being apprehended than 
about the consequences if they are caught. This 
makes sense because they can do little to avoid 
punishment if caught, but they can do a lot to reduce the 
risks of capture by being careful. This is why situational 
prevention seeks to increase the risks of being caught and 
makes no attempt to manipulate punishment. 

Extend guardianship. Cohen and Felson showed that 
the increase in residential burglary during the 1960s and 
1970s was partly due to the increasing numbers of 
women working outside the home. This meant that for 
much of the day many homes, if not entire suburbs, had 
no "capable guardians." Other research has found that 
burglars prefer to commit their crimes on weekday 
afternoons when people are likely to be out. This explains 
why people should cancel newspapers and inform their 
neighbors when they go on vacation. Carrying a cell 
phone or going out at night in a group are other ways to 
extend guardianship. Little is known about the 
effectiveness of these routine precautions and evaluations 
of neighborhood watch, the only systematic effort to 
extend guardianship, have not been encouraging. 
However, "cocoon" neighborhood watch, under which 
surrounding homes were alerted after a burglary, was an 
important element of a successful project in Kirkholt 
in England. 

Assist natural surveillance. Homeowners trim bushes 
near their windows and doors and banks light their 
interiors at night to capitalize on the "natural" 
surveillance provided by people going about their 
everyday business. Enhancing natural surveillance is also 
the prime objective of improved street lighting and 
defensible space architecture. Studies in the U.K. have 
found that improved lighting in public housing reduces 
crime with little evidence of displacement. One 
component of an early CPTED intervention to reduce 
burglary in a commercial strip in Portland, Oregon, was 
improved lighting of the outside of stores. Oscar Newman 
has reported successes in reducing crime in public housing 
through the application of natural surveillance principles. 
Finally, informant hotlines and crime-stopper programs are 
attempts to capitalize on the natural surveillance provided 
by the public. 

Reduce anonymity. Expanded car ownership has 
allowed people to work far from their homes. The 
development of out-of-town malls has led to the decline 
of downtown shopping. Low-cost travel has led to 
increased tourism both at home and overseas. As a result, 
people spend increasing periods of time among 
anonymous strangers. The building of large schools has 
contributed to this trend because pupils are less well 
known to staff and other pupils. Reducing anonymity is a 
promising but rarely used situational technique. Some 
schools are now requiring uniforms, partly to reduce the 
anonymity of pupils on their way to and from school. Cab 
driver ID badges and "How's my driving?" decals with 1800 
numbers on trucks are two further ways of 
reducing anonymity. 

Use place managers. In addition to their primary 
function, some employees also perform a surveillance role. 
These "place managers" include sales assistants, hotel 
door-men, and parking lot attendants. Canadian research 
has found that apartment complexes with doormen are 
less vulnerable to burglary. Rewarding cashiers for 
detection of forged or stolen credit cards helped to reduce 
annual fraud losses by nearly $1 million at an electronics 
retailer in New Jersey. Vandalism on a large fleet of 
double-decker buses in northern England was 
substantially reduced when a few of the buses were fitted 
with video cameras for drivers. Having two clerks on duty, 
especially at night, has consistently been found effective 
in preventing robbery of convenience stores (see table). 

Strengthen formal surveillance. Formal surveillance is 
provided by police, security guards, and store detectives, 
all of whom furnish a deterrent threat to potential 
offenders. Burglar alarms, video cameras, and speed 
cameras can enhance this surveillance. A study of an 
affluent community near Philadelphia found that 
widespread ownership of burglar alarms reduced police 
costs by lowering burglary rates for the community at 
large. Home Office studies have found appreciable 
reductions in a variety of crimes following installation of 
video cameras in British cities (see Video Surveillance of 
Public Spaces, Problem-Oriented Guides for Police, 
Response Guide No.3, accessible at www.cops.usdoj.gov 
and www.popcenter.org). An evaluation of photo radar 
deployed state-wide in Victoria, Australia, showed that it 
reduced speeding and contributed to a 45 percent 


reduction in traffic fatalities. A well-publicized bike patrol 
provided by a private security company in a large park-
and-ride lot in suburban Vancouver, Canada led to a 
substantial drop in theft of cars. When security personnel 
began systematic, daily counts of high-risk merchandise, 
such as VCRs and camcorders, thefts by employees 
dropped by more than 80 percent in the warehouse of a 
New Jersey electronics superstore. Powerful new ways of 
enhancing formal surveillance are provided by linking 
data-sets on individuals, as shown in a study by Eckhart 
Kuhlhorn. He demonstrated that computerized 
crosschecking of statements of personal income made by 
claimants to two separate Swedish government 
departments reduced welfare frauds. When people 
claimed for rent allowance they were tempted to 
understate income, but when they claimed sickness 
benefits, they were tempted to overstate it. The ability to 
crosscheck the income statements substantially reduced 
these frauds. 

Read More: 

Painter, Kate and Nick Tilley (1999). "Surveillance of 
Public Space: CCTV, Street Lighting and Crime 
Prevention." Crime Prevention Studies, volume 10. 
Monsey, NY: Criminal Justice Press. (Accessible in part at 
www.popcenter.org). 

Table: Measures that Reduce Robbery of 
Convenience Stores 
(Results of 14 Studies) 

Two or more clerks - # of supporting studies*, 10
Good cash handling - # of supporting studies*,
No concealed entrances - # of supporting studies*,
Nearby stores - # of supporting studies*,
Clear view of store front - # of supporting studies*,
Closed at night - # of supporting studies*,
Security technology - # of supporting studies*,
Cashier in secure booth - # of supporting studies*,
Employee training - # of supporting studies*,
Clear view inside store - # of supporting studies*,
Gas pumps at front - # of supporting studies*,
Cashier in center of store - # of supporting studies*,
Store on busy street - # of supporting studies*,
Security guard present - # of supporting studies*,
Number of supporting - # of supporting studies*,
 
*Not all studies included all measures 
Source: Hunter and Jeffery (1997). "Preventing 
Convenience Store Robbery through Environmental 
Design." Situational Crime Prevention: Successful 
Case Studies, Ronald Clarke. Monsey, NY: Criminal 
Justice Press. 

Table: Increase The Risks Of Crime 

Extend guardianship 
 Promote routine precautions such as leaving signs of 
occupancy when away from the house, carrying a cell 
phone and going out at night in a group 
 "Cocoon" neighborhood watch 
Assist natural surveillance 
 Improved street lighting 
 Defensible space design 
 Neighborhood watch and informant hotlines 
Reduce anonymity 
 Cab driver IDs 
 "How's my driving?" decals 
 School uniforms 
Use place managers 
 Train employees to prevent crime 
 Reward vigilance 
 Support whistleblowers 
Strengthen formal surveillance 
 Speed cameras and random breath testing 
 Video surveillance of downtowns 
 Focused bike patrols in parking lots 


41. Reduce the rewards of crime

Rational choice theory holds that offenders are 
always seeking to benefit themselves by their 
crimes. These benefits may not simply be material, 
as in theft, because there are many other rewards of 
crime, including sexual release, intoxication, excitement, 
revenge, respect from peers, and so forth. An important 
strand of situational crime prevention is therefore to 
understand the rewards of any particular category of 
offending and to find ways of reducing or removing them. 

Conceal targets. Householders often try to foil burglars 
by hiding jewelry or other valuables. They also keep their 
curtains drawn to stop thieves from looking through the 
windows to see what they own. Some people don't wear 
gold chains in public, and others avoid leaving their cars 
overnight on the streets if these are models attractive to 
joyriders, such as Hondas and Acuras. The table presents 
British Crime Survey data showing that cars left on the 
street are at very much greater risk of theft than those left 
in the owner's garage or driveway. These are all ways to 
conceal targets and reduce temptation. Some other 
concealment strategies are less obvious. For example, 
gender-neutral phone lists can help protect women from 
obscene phone calls, and unmarked armored trucks can 
reduce the risk of in-transit robbery. 

Table: Car Thefts and Parking Place, England and Wales, British Crime Survey 
Table Headers: Where parked, Car crimes* per 100,000 cars per 24 hours 
Garage at home, 2 
Drive/carport, 40 
Other street, 327 
Public parking lot, 454 

*Includes theft of, theft from, attempts and deliberate damage 

Source: Clarke, Ronald and Pat Mayhew (1998). "Preventing Crime in Parking Lots." 
Reducing Crime through Real Estate Development and Management, Marcus Felson and 
Richard Peiser. Washington, DC: Urban Land Institute. 

Remove targets. The installation of a machine that 
accepted credit cards in a Spanish church brought several 
benefits: donors received receipts for tax purposes, the 
church received larger gifts, and, since cash was not 
deposited, the church reduced its theft risk through 
removing targets. An earlier application of this same 
situational technique comes from the days of the 
Californian Gold Rush. Plagued by robberies of 
stagecoaches, one mine started casting gold in 400pound 
cubes. These were too heavy for robbers to carry 
away on horseback. More up-to-date examples of target 
removal are provided by changes made to pay phones. To 
stop people from smashing glass, wall-mounted booths 
have been substituted for kiosks in high-risk locations in 
the U.K. and prepaid cards that dispense with the need to 
store large sums of cash have removed an important 
target for theft. Perhaps the most striking example of 
target removal is the introduction of exact fare systems 
and safes on buses, which dramatically reduced robberies 
of bus drivers in New York and in 18 other cities in the 
late 1960s. 

Identify property. Motor vehicles in developed 
countries must be registered and must carry a unique 
Vehicle Identification Number (VIN). This is to assist 
taxation, but these measures also reduce theft. One of the 
last states to require vehicle registration was Illinois in 
1934, whereupon vehicle thefts declined from 28,000 in 
the previous year to about 13,000. More recently, the 
federal Motor Vehicle Theft Law Enforcement Act of 1984 
has mandated the marking of all major body parts of 
"high-risk" automobiles with VINs. Police "operation 
identification" programs have had limited success in this 
country, but Gloria Laycock of the Jill Dando Institute of 
Crime Science found that property marking undertaken in 
three small communities in Wales, combined with 
extensive media publicity, halved the number of reported 
domestic burglaries. 

Disrupt markets. Criminologists and police have 
devoted rather little attention to understanding and 
disrupting markets for stolen goods. Criminologists have 
found it difficult to obtain data about these markets, and 
the police have preferred to pay more attention to 
catching thieves and burglars than fences, partly because 
the penalties for fencing stolen goods are relatively light. 
However, if there were no market for stolen goods there 
would be few persistent burglars and few thefts of trucks 
carrying large loads of tobacco and alcohol. Recent work 
for the Home Office by Mike Sutton has awakened 
interest in disrupting markets for stolen goods. The 
disruptive measures need to be tailored to the nature of 
the market and they include systematic monitoring of 
pawn shop transactions by the police, crackdowns on 
illegal street vendors, and monitoring of small ad sales in 
newspapers to detect repeat vendors. Police "sting" 
operations - such as bogus used goods stores - should be 
avoided because research has found that they may 
stimulate theft in the area around the sting. 


Deny benefits. Installing speed humps is a sure way to 
deny the benefits of speeding. Security-coded car radios 
and ink tags provide further illustrations of crime 
prevention techniques. Security-coded radios cannot be 
used unless the thief knows the PIN and, according to 
studies undertaken in the United States and in Australia, 
cars with these radios have lower theft rates. Ink tags are 
used in clothing stores to prevent shoplifting. They release 
ink if tampered with and indelibly the stain garment to 
which they are attached. The thief cannot wear the 
garment or sell it, which removes the incentive for theft. 

Read More: 

Sutton, Mike and colleagues (2001). Tackling Stolen 
Goods with the Market Reduction Approach. Crime 
Reduction Research Series Paper 8. London: Home Office. 

Table: Reduce Rewards
Conceal targets 
 Off-street parking for cars attractive to joyriders 
 Gender-neutral phone directories 
 Unmarked armored trucks 
Remove targets 
 Removable car radios 
 Women's shelters 
 Pre-paid cards for payphones 
Identify property 
 Property marking 
 Vehicle licensing and parts marking 
 Cattle branding 
Disrupt markets 
 Checks on pawn shops 
 Controls on classified ads 
 License street vendors 
Deny benefits 
 Ink merchandise tags 
 Graffiti cleaning 
 Disable stolen cell phones 
 
Denying The Benefits Of Graffiti
Graffiti-covered subway trains became almost a trademark of New York City in the 1970s and 1980s, and they 
frequently appeared in the opening sequences of movies that were set there. The subway authorities had tried 
innumerable law enforcement and target-hardening strategies to rid the subway cars of graffiti, but with little result. 
Eventually they hit upon a simple idea that brought them success: Once a car had been cleansed of graffiti it would 
immediately be withdrawn from service and cleaned again if it attracted fresh graffiti. This effectively denied 
"taggers" the benefits of "gettin up" and seeing their handiwork on public display. Because of the huge number of 
subway cars, it took six years before all the cars were clean. Nowadays, they are no worse than subway cars in other 
cities. 

Table: Clean Cars 
Year 1984, Goal none, Actual 400
Year 1985, Goal 1720, Acutal 1915
Year 1986, Goal 3434, Acutal 3454
Year 1987, Goal 4707, Acutal 4839
Year 1988, Goal 5946, Actual 6077
Year 1989, Goal 6221, Actual 6245

Source: Sloan-Howitt, Maryalice and George Kelling (1997) "Subway Graffiti in New York City: Gettin up vs. Meanin 
it and Cleanin it." Situational Crime Prevention: Successful Case Studies, Ronald Clarke, Monsey, NY: Criminal Justice 
Press. 
 

42. Reduce provocations

When studying prisons and pubs, Richard Wortley 
noticed that crowding, discomfort, and rude 
treatment provoked violence in both settings. This 
led him to argue that situational prevention had focused 
too exclusively on opportunities for crime and had 
neglected features of the situation that precipitate or 
induce crime. As a result of his work, Clarke and Cornish 
have included five techniques to reduce what they called 
"provocations" in their new classification of situational 
techniques. These techniques are explained below, 
drawing on Wortley's examples. 

Reduce frustration and stress. Everyone gets angry 
when treated rudely by waiters, when people push in front 
to be served, or when trains are delayed with no 
explanation. Sometimes they get so angry they become 
violent. This could be avoided by improved service, which 
is increasingly being demanded and delivered. However, 
complaints may be ignored when those mistreated have 
little power. For example, prisoners are often ignored 
when they complain that they cannot eat when hungry or 
choose their TV programs, even though these complaints 
could be met quite easily by staggering meal times and 
providing more TVs. Waiting one's turn to use the phone, 
another source of frustration for prisoners, can be reduced 
by computerized systems to ration phone use (see box). 
Outbursts of anger and violence can also result from 
people being subjected to extreme discomfort - too much 
noise, being jostled, and having nowhere to sit. These 
conditions exist in many clubs, bars, and delayed 
passenger airline flights and have consistently been found 
to induce trouble. More seating, soothing music, and 
muted lighting are all ways to reduce stress in 
these settings. 

Avoid disputes. In the U.K., rival groups of fans are 
segregated in soccer stadiums and their arrival and 
departure is scheduled to avoid the periods of waiting 
around that promote trouble. Taxi fares from New York 
City's Kennedy Airport to Manhattan are fixed at a 
standard $45 to prevent cheating and disputes over fares. 
In an attempt to produce consensual crowd management 
at the Australian Motorcycle Grand Prix, riders were 
allowed to operate camp-sites for their fellow 
motorcyclists and were encouraged to develop rules for 
use of the facilities. This helped to eliminate the brawls 
between police and motorcyclists, which had marred the 
event in previous years. 

Reduce arousal and temptation. Male doctors should 
not conduct detailed physical examinations of female 
patients without a nurse or receptionist present. This 
protects the doctor from false accusations, but it also 
reduces the temptation to sexually abuse the patient or 
make inappropriate advances. Laws that prohibit 
convicted pedophiles from taking jobs involving contact 
with children not only protect children, but also help 
adults to manage their sexual desires. That the very sight 
of a gun has been found to trigger feelings of aggression 
provides one good reason for regulating the display of 
weapons. Similarly, the fact that high proportions of sex 
offenders own or use violent pornography provides a 
rationale for controlling these materials. Finally, reducing 
temptation is the basis for advice about being careful with 
one's money in public as well as advice to young women 
about being careful when out alone at night. 

Neutralize peer pressure. Many parents discourage 
friends who are a "bad influence" on their children and 
schools disperse groups of troublemakers into different 
classes. But adults as well as children are subject to peer 
pressure. Existing staff may induct new workers into 
stealing from their employers, and young men are often 
encouraged to drink too much by friends. One publicity 
campaign mounted in Australia to reinforce the powerful 
deterrent impact of random breath testing made use of 
the slogan, "Good mates don't let mates drink and 
drive." A publicity campaign in this country used "Friends 
don't let friends drive drunk." 

Discourage imitation. All new television sets contain a 
"V-chip" so that parents can program their TVs to prevent 
children from viewing violent programs. Though the link 
between violent movies and violence in society is much 
disputed, there is some evidence of "copycat" crimes 
because media reports of unusual crimes sometimes 
provoke imitation elsewhere. It has also been shown, for 
example, that students who see their teachers engaging in 
illegal computer activity are more likely to commit 
computer crimes themselves, and that other pedestrians 
will follow someone crossing against a red light. Indeed, 
how often have you "run the red" only to find when 
glancing in your rear-view mirror that so has the car 
behind you? It has also been shown that picnic tables in 
parks that had been scratched and carved are more than 
twice as likely to attract further damage. Findings such as 
these provide the rationale for "rapid repair" programs to 


deal with vandalism. Wilson and Kelling extended this 
principle in their famous "broken windows" article by 
arguing that the failure to deal promptly with minor signs 
of decay in a community, such as panhandling or soliciting 
by prostitutes, can result in a quickly deteriorating 
situation as hardened offenders move into the area to 
exploit the breakdown in control. 

Read More: 

Wortley, Richard (2001). "A Classification of Techniques 
for Controlling Situational Precipitators of Crime." Security 
Journal, 14: 63-82. 

List: Reduce Provocations
FIND A PRACTICAL RESPONSEReduce frustration and stress 
 Efficient lines and polite service 
 Expanded seating capacity 
 Soothing music and muted lighting 
Avoid disputes 
 Separate enclosures for rival soccer fans 
 Reduced crowding in pubs 
 Fixed cab fares 
Reduce arousal and temptation 
 Controls on violent pornography 
 Prohibitions on pedophiles working with children 
 Advice about avoiding sexual victimization 
Neutralize peer pressure 
 "Idiots drink and drive" 
 "It's OK to say No" 
 Disperse troublemakers at school 
Discourage imitation 
 Rapid repair of vandalism 
 V-chips in TVs 
 Censor details of modus operandi to avoid 
"copycat" crimes 

Phone Fraud, Slot Time, and Victoria Secrets at Rikers Island 
Rikers Island, a stone's throw from New York City's La Guardia Airport, is a huge system of 10 jails. These house 
different categories of inmates, whose phone privileges vary with their status. Corrections officers were supposed to 
use logbooks to record phone use and to regulate the amount of time each inmate spent on the phone. In the early 
1990s, this system had broken down. Inmates had developed their own system, known as "slot time", and the 
annual cost of calls had escalated to more than $3 million. The most powerful inmates controlled the phones, which 
they often used to access their beepers and maintain their drug businesses in the outside world. Inmates were also 
accessing "sex lines" and were using stolen credit card numbers to make long distance calls and purchases. Nancy 
La Vigne, who studied this problem as a graduate student at Rutgers University, notes, "The female inmates did just 
this, accessing the Victoria Secrets catalogue, which resulted in a jail that could boast the best-dressed inmates in the 
country - until officials caught on." 

The officials introduced a high-security computerized phone system that put strict limits on phone use, in line with 
the status of the caller. Detainees gained access to the phones through bar codes on their ID cards and by entering a 
PIN. This system immediately cut phone costs in half, but it was also noticed that fewer fights were erupting over 
access to the phones. In fact, La Vigne's study showed that the monthly rate of these fights dropped from 6.7 per 
1,000 inmates in the year before the new phone system to 3.6 per 1,000 after its introduction. 

Source: La Vigne, Nancy (1994). Rational Choice and Inmate Disputes over Phone Use on Rikers Island". Crime 
Prevention Studies, volume 3, Ronald Clarke. Monsey, NY: Criminal Justice Press. 

43. Remove excuses for crime

This fifth category of situational techniques recognizes 
that offenders make moral judgments about their 
behavior and that they often rationalize their conduct 
to "neutralize" what would otherwise be incapacitating 
feelings of guilt or shame. They make such excuses as: 
"He deserved it," "I was just borrowing it," and "I only 
slapped her." These excuses may be especially important 
for ordinary people responding to everyday temptations to 
evade taxes, drive when drunk, sexually harass junior 
employees and steal employers' property. 

Set rules. All organizations make rules about conduct in 
their fields of governance. For example, businesses 
regulate employees' time-keeping and stores require sales 
assistants to follow strict cash-handling procedures. 
Organizations such as hospitals, public libraries and hotels 
must, in addition, regulate the conduct of the clients they 
serve. Any ambiguity in these regulations will be exploited 
if it benefits the client. One important strand of situational 
prevention, therefore, is rule setting - the introduction of 
new rules or procedures (and the clarification of those 
already in place) to remove any ambiguity concerning the 
acceptability of conduct. For example, in attempting to 
reduce "no-shows," many restaurants will now only 
accept reservations if callers leave a telephone number 
where they can be reached. Some also require a credit 
card number so that a charge can then be made for no-
shows. Requiring anglers in California to wear their 
fishing licenses was successful in getting more of them to 
comply with license purchase rules. 

Post instructions. Work rules are often set out in 
employment contracts, and rules established by credit card 
companies, telephone providers, and insurance companies 
are contained in the service contracts. Regulations 
governing public places or facilities may be publicly 
posted, either to prevent people claiming ignorance of the 
rules or to show precisely where these apply. The roads, in 
particular, make extensive use of signs governing driving 
or parking. Studies have found that warning signs 
significantly reduce illegal parking in spaces reserved for 
disabled drivers. Many other facilities - parks, colleges, 
transit lines and housing projects - also post signs to 
govern a wide range of behaviors. Despite their wide use, 
there have been few evaluations of the preventive 
effectiveness of posted instructions - but they are an 
essential tool of law enforcement and are often used in 
problem-solving efforts. 

Alert conscience. This situational technique differs from 
"informal social control" in two important respects. First, 
the focus is on specific forms of crime occurring in 
discrete, highly limited settings and, second, the purpose 
is to alert conscience at the point of committing a specific 
kind of offense rather than attempting to bring about 
lasting changes in generalized attitudes to law breaking. 
For example, signs at store entrances announce 
"Shoplifting is stealing," and in Manhattan's Port 
Authority Bus Terminal signs proclaim "Smoking here is 
illegal, selfish and rude." Roadside speed-boards give 
immediate feedback (without issuing fines) to motorists 
traveling above the speed limit. 

Assist compliance. When Italian criminologist Cesare 
Lombroso suggested in the 19th century that people 
should be locked up for urinating in the streets, his pupil 
Enrico Ferri suggested a more practical way to solve the 
problem: build public toilets. This constitutes an example 
of facilitating compliance, a technique of wide application. 
It includes subsidizing taxi rides for those who have been 
drinking, providing litter baskets and "graffiti boards" (for 
people's public messages), and improving checkout 
procedures in libraries, which reduce delay and thus 
excuses for failing to comply with rules for book 
borrowing. In a classic paper on Disney World, Shearing 
and Stenning provide a fascinating glimpse into the ways 
in which sophisticated crowd control and management involving 
the use of pavement markings, signs, physical 
barriers (which make it difficult to take a wrong turn) and 
instructions from cheerful Disney employees - greatly 
reduce the potential for crime and incivility in the theme 
park (see box). 

Control drugs and alcohol. Crime is facilitated by 
alcohol and drugs, which undermine inhibitions or impair 
perception and cognition so that offenders are less aware 
of breaking the law. The value of situational controls on 
drinking has often been demonstrated. Johannes 
Knutsson, research director at the Norwegian Police 
College, has shown that limiting the amount of alcohol 
that individuals could bring into a Swedish resort town on 
Midsummer Eve helped to reduce drunkenness and 
disorderly conduct. The small community of Barrow, 
Alaska, instituted a total ban in 1994 on the sale of 
alcohol to curb binge drinking, which led to an 81 percent 
drop in alcohol-related calls for service, a reduction of 43 
percent in felonies, and drop of more than 90 percent in 


removals of drunken people from public places (see 
Goldstein Award submission at www.popcenter.org). 
Voluntary agreements reached among local drinking 
establishments to promote responsible drinking have 
reduced alcohol-related crime in numerous nightlife areas 
in Australia. Rutgers University has decreed that beer 
must be served from kegs instead of cases at dorm parties 
because cases are easier to hide and, as one student said: 
"If you have one keg and a line of 20 people behind it, 
people will get less alcohol than if you had a refrigerator 
and people were throwing out beer." 

List: Remove Excuses
FIND A PRACTICAL RESPONSESet rules 
 Rental agreements 
 Harassment codes 
 Hotel registration 
Post instructions 
 "No Parking" 
 "Private Property" 
 "Extinguish camp fires" 
Alert conscience 
 Roadside speed display boards 
 Signatures for customs declarations 
 "Shoplifting is stealing" 
Assist compliance 
 Easy library checkout 
 Public lavatories 
 Litter bins 
Control drugs and alcohol 
 Blood alcohol self-testing in bars 
 Server intervention 
 Alcohol-free events 

List: Arriving at Disney World
 Signs tell visitors arriving by car to tune into Disney radio for information. 
 Signs direct them to the parking lot they must use and road markings show the way. 
 Smiling parking attendants direct visitors to their space and loudspeakers remind them to lock their cars. 
 Visitors are directed to rubber-wheeled trains to take them to the monorail. 
 Recorded announcements direct them to stand safely behind guardrails. 
 They are reminded about the location of their parking space (e.g., Donald Duck 1). 
 They are (politely) asked to sit, to keep their arms and legs within the confines of the carriage, and to make sure 
children do the same. 
 Before disembarking, they are told how to get to the monorail and barriers stop them from going the wrong way. 
 On the platform, attendants guide them into corrals the right size to fill one compartment of the monorail. 
 Safety gates at the platform edge open only when the monorail arrives. 
 Any delays in service are announced and expected times of arrival are given. 
 On board, passengers are asked to remain seated "for your own safety". 
 Passengers are told how to disembark and how to move to the first entertainment. 
 They are once again reminded to look after their children and to take their possessions. 
 While waiting to enter each exhibit, visitors are marshaled in lines, which indicate waiting times; those in line are 
entertained by Disney characters. 
 On leaving the exhibit, they are guided by signs, barriers and attendants to the next one. 
 
Source: Shearing, Clifford and Phillip Stenning (1997). "From the Panopticon to Disney World: The Development of 
Discipline". Situational Crime Prevention: Successful Case Studies (2nd ed.), Ronald V. Clarke. Monsey, NY: Criminal 
Justice Press. 


44. Find the owner of the problem

Many problems arise through the failure of some 
institution - business, government agency, or 
other organization - to conduct its affairs in ways 
that prevent crime rather than cause it. In short, many 
problems occur because one or more institutions are 
unable or unwilling to undertake a preventive strategy, or 
because these institutions have intentionally established a 
circumstance that stimulates crimes or disorder. This 
creates risky facilities (Step 28) and other concentrations 
of crime. 

Solving problems usually requires the active cooperation 
of the people and institutions that have failed to take 
responsibility for the conditions that lead to the problem. 
These problem owners have shifted responsibility for the 
problem from their shoulders to the shoulders of the 
public and the police. Consequently, an important 
objective of any problem-solving process is to get them to 
assume responsibility. So for any problem, you need to 
answer three ownership questions: 

 Who owns the problem? 
 Why has the owner allowed the problem to develop? 
 What is required to get the owner to undertake prevention? 

Who owns the problem? When a problem is located at 
a specific place, it is usually easy to identify who is 
responsible. The owner of the problem is the owner of the 
location. A problem in a park, for example, is the body 
with the responsibility for operating the park - usually a 
local government or some private agency. 

It is more difficult to identify those responsible for 
problems that are spread over larger areas. If a 
widespread problem is focused on a specific location, then 
that location may be the source for the events in the 
surrounding area, and the owner of the central location 
may be responsible. A real estate speculator, who owns 
many derelict properties in a neighborhood, owns the 
crime associated with these properties. 

If there is a special group of individuals - the elderly, 
children with special needs, or victims of domestic 
violence - and these individuals are targets of crime or 
disorder, then potential owners of the problem are family 
members. If there are agencies charged with seeing to 
the well-being of these special groups, these service 
agencies are possible co-owners of the problems. While 
trying to reduce the highway deaths of migrant workers, 
the California Highway Patrol identified businesses that 
specialized in the transportation of migrant workers. They 
owned the problem but were not being responsible. 
Fixing responsibility entailed stepped up regulation of 
these businesses, including vehicle inspections, requiring 
seats and seat belts for certain types of migrant transport 
vehicles, and greater enforcement of safety violations. The 
result was a large reduction in fatal accidents involving 
migrant farm workers. This effort received the Goldstein 
Award for Problem-Solving Excellence in 2002. 

Why has the owner allowed the problem to 
develop? There are four generic explanations that alone 
or in combination fit most problems: 

1. An institution may be unable to prevent crime. This 
might be due to ignorance as to the effect of its 
operations on crime or ignorance as to how to prevent 
crime. Or this may be due to lack of resources, even 
when the institution knows its operations help create 
crime. It is also important to recognize the importance 
of institutionalized procedures. Changing procedures 
can be time consuming and costly in both monetary 
resources and staffing. A new inventory control 
procedure to prevent shoplifting and internal theft may 
be difficult to implement because it requires disruptive 
changes in the ways employees conduct their 
normal business. 

2. Some institutions may be unwilling to prevent crime 
facilitated by their operations because they believe that 
fixing crime is the exclusive responsibility of the police 
(e.g., gas stations with a high rate of gasoline drive-offs 
may see gas thieves as the problem rather than their 
lack of a pre-pay policy). Rather than recognize the role 
of opportunity in creating crime, some people dwell 
exclusively on the role of offenders. From this 
perspective, it is the function of police to reduce crime 
by stricter enforcement. The limitations of this approach 
have been noted in Step 3. Another source of 
unwillingness is the belief that the police are intruding 
on the property owner's rights. A retailer might claim 
that he has the right to display goods any way he 
wants, and that the police should not compel, or even 
suggest, alternative displays that might 
reduce shoplifting. 


3. Some institutions are unwilling because of the costs of 
addressing the problem; they gain more by ignoring 
crime than they lose. They may perceive that the costs of 
prevention outweigh any benefits to them. Security 
personnel at an entertainment venue are costly, and 
quality security personnel are more costly. If the costs of 
the problem are not borne by the facility, then there is 
little perceived need to bear the costs of prevention. In 
essence, such facilities are exporting the costs of crime 
and prevention onto others, and thereby reducing their 
own costs. 

4. Some institutions may profit from the crimes, as can 
happen when a used goods shop does little to verify 
legitimate ownership of the merchandise they display. 
Auto repair garages can purchase stolen car parts 
cheaper than legal car parts, thus increasing their profit 
margin. 

What is required to get the owner to undertake 
prevention? Herman Goldstein has outlined a rough 
hierarchy of interventions designed to shift responsibility 
for problems from the police back to the institutions that 
own them (see box). 

Moving from the bottom to the top of Goldstein's list, 
interventions become less cooperative and increasingly 
coercive. Because of this, the difficulty of intervention 
increases, along with the costs of failure to the police, as 
one moves up the list. Consequently, the value of 
information and thorough analysis increases from the 
bottom to the top. As Goldstein notes, this hierarchy is a 
rough indicator of these trends rather than an exact 
description. Nevertheless, it is useful for planning a 
layered set of responses to a problem - beginning with 
the most cooperative and working upward only if needed 
and only when supported by information. 

Shifting responsibility back to the owner of the problem 
can create legal and political conflicts. Institutions that 
had gained from the problem, or foresee a cost in taking 
responsibility for it, are unlikely to simply agree to a 
suggestion that they do something about it. The problem 
of false alarms has been a plague for over two decades, 
but in many jurisdictions it is difficult to overcome the 
political and financial clout of the alarm industry who are 
principally responsible for the high level of false alarms. 
Clearly, the least costly and intrusive prevention measures 
will meet the least resistance (Step 45). But if these 
responses turn out to be ineffective, then the police often 
face a difficult choice: demand greater responsibility from 
problem owners and risk a political conflict, or continue to 
spend the public's money on a problem created by a few 
individuals. In the abstract the answer seems clear, but in 
practice it is often a difficult decision. 

Read More: 

Scott, Michael (2005). "Policing for Prevention: Shifting 
and Sharing the Responsibility to Address Public Safety 
Problems." Handbook of Crime Prevention and 
Community Safety, Nick Tilley. Cullompton U.K.: Willan. 

Flowchart: Herman Goldstein's Hierarchy of Ways to Shift Ownership 
Least cooperative/ Most difficult to Most cooperative/ Least difficult 

Bringing a Civil Action 
Legislation Mandating Adoption of Prevention 
Charging a Fee for Police Service 
Withdrawing Police Service 
Public Shaming 
Creation of a New Organization to Assume Ownership 
Engaging Another Existing Organization 
Targeted Confrontational Requests 
Straightforward Informal Requests 
Educational Programs 


45. Choose responses likely to be implemented

Finding a suitable response can be a troublesome 
process. You may be repeatedly disappointed when 
promising interventions are vetoed because of 
expense or difficulty, or because of lack of cooperation. 
But there is more than one way to solve a problem. So, 
eventually your team will agree on a response that meets 
some basic requirements: 

 It is not too ambitious or costly. 

 It focuses on near, direct causes rather than on distant, 
more indirect ones, which gives it a good chance of 
making an immediate impact. 

 The mechanism through which each response should 
impact the problem has been clearly articulated. 

So, at last your worries are over and you can relax, right? 
Wrong! Even more difficult than agreeing on a good 
response is to make sure that it is actually implemented. 
You cannot ensure this on your own, but if you know the 
pitfalls of implementation, you can steer the partnership 
away from choosing responses that can fall prey to these. 
Tim Hope and Dan Murphy identified these pitfalls when 
studying a vandalism prevention project in eleven schools 
in Manchester, England. 

The responses to be implemented at each school were 
selected by groups of local government officials, school 
staff and police. Much of the damage was more careless 
than malicious. This suggested two different solutions: 
situational responses to protect the buildings or providing 
recreational activities to divert children into less harmful 
activities. Only one of the eleven groups recommended 
improved leisure provision. The situational responses 
recommended were mostly basic target-hardening 
(window grills, toughened glass and high fences), though 
proposals also included a plan to encourage local 
residents to keep an eye on two adjacent schools and a 
plan to move a playground to a less vulnerable area. 

At only two schools were all the recommendations 
implemented. In three, none was put in place and at the 
remaining six schools one or more recommendations 
failed to materialize. These failures to implement meant 
there was little impact on vandalism. Hope and Murphy 
identified five main obstacles to implementation, all of 
which have been encountered in U.S. problem-solving 
projects: 

1. Unanticipated technical difficulties. For eight 
schools, the groups recommended the replacement of 
vulnerable windows with polycarbonate glazing or 
toughened glass. However, not a single pane of either 
type was installed. The city architects had prohibited 
polycarbonate glazing because in case of fire it would 
prevent escape and might give off toxic fumes. 
Toughened glass had to be cut to size before it was 
toughened, but the panes came in many sizes and it 
would have been difficult to store a few of each size 
in readiness. The alternative of supplying a pane to 
order was ruled out by the long time (six weeks) it 
would take to do this. 

2. Inadequate supervision of implementation. At 
one school it was agreed to move the playground to 
a less vulnerable area. The original playground was to 
be replaced with flowerbeds, but this had to be done 
by a government agency that got no further than 
providing an estimate for the work. The relocation of 
the playground was sub-contracted to a private 
builder, but due to a misunderstanding only half the 
proposed area was resurfaced. After two years, therefore, 
vandalism was unchanged, there were no 
flowerbeds, and the school had acquired a useless, 
narrow strip of pavement. 

3. Failure to coordinate action among different 
agencies. Every recommendation that was the sole 
responsibility of the buildings maintenance section of 
the school system was implemented, while none of 
those involving other departments or agencies ever 
materialized. For example, it was recommended that 
people living near two schools should be encouraged 
to keep an eye on them after hours and report anything 
suspicious to the police. This required the 
cooperation of the school system administration, the 
principal, staff and pupils of the schools and three 
branches of the police - crime prevention, community 
relations and local police. All liked the idea, but no 
one would take the lead. 

4. Competing priorities. During the implementation 
period many other demands were placed on the 
school system as a result of widespread labor unrest 
by local government employees and a school 
reorganization made necessary by a declining school-
age population. School staffing changes resulted in 
the reassignment of staff who were involved in the 
vandalism project. It is not surprising that the staff 
gave the vandalism project low priority. 


5. Unanticipated costs. In some cases, the wider 
consequences of a particular course of action 
outweighed its immediate benefits. For example, at 
the school with the most serious vandalism problem it 
was decided to mount a security patrol for the 
upcoming holiday period. The school maintenance 
workers were employed to patrol the school for 
payment during their spare time. This was 
immediately successful in reducing vandalism and was 
extended beyond school holidays to provide coverage 
at evenings and weekends. Other schools demanded 
the same protection and more maintenance workers 
wanted the additional overtime opportunities. 
Ultimately the cost became too high and the project 
was scrapped. 

You can see from the list above that some 
implementation problems cannot be anticipated and that 
a proportion of all responses selected will never be 
implemented. However, it is also clear that certain kinds 
of responses can be expected to encounter problems and 
these are summarized in the box. In some cases, of 
course, a response may be so promising that it is worth 
pursuing despite the risks of implementation failure. But 
being forewarned is to be forearmed. 

Read More: 

Hope, Tim and Daniel Murphy (1983). Problems of 
Implementing Crime Prevention: The Experience of a 
Demonstration Project. The Howard Journal, XXII, 38-50. 

Laycock, Gloria and Nick Tilley (1995). Implementing 
Crime Prevention. In Building a Safer Society, edited by 
Michael Tonry and David Farrington University of 
Chicago Press. 

List - Expect implementation problems when a response:
 Requires coordinated action among a number of separate agencies. 
 Will take a long time to introduce and involves a number of steps to be completed in sequence. 
 Must be implemented by staff with little understanding of its purpose. 
 Has no major supporter among the partnership team. 
 Lacks the support of senior administrators. 
 

List - Also expect problems when the response must be implemented by an agency: 
 That is outside the partnership. 
 That is poorly resourced or in turmoil. 
 That will gain little direct benefit from the solution. 


46. Conduct a process evaluation

The first critical step in assessment is to conduct a 
process evaluation. It answers the question,"Was the 
intervention put into place as planned and how was it 
altered for implementation?" As shown in the figure, a 
process evaluation focuses on the resources that were 
employed by the response (inputs) and the activities 
accomplished with these resources (results), but it does not 
examine whether the response was effective at reducing 
the problem (outcomes). For that you need an impact 
evaluation. An impact evaluation tells you whether the 
problem changed (Steps 47 to 53). 

ROLES OF PROCESS AND IMPACT EVALUATIONS 

Both types of evaluations are needed in a POP project. The 
table summarizes possible conclusions based on the 
findings of both types of evaluation. A) The response was 
implemented in accordance with the plans, and there are 
no other reasonable explanations for the decline. So there 
is credible evidence that the response caused the reduction. 
B) The response was implemented as planned, but there 
was no reduction in the problem. So there is credible 
evidence that the response was ineffective. 

But what if the response was not implemented as planned? 
In this case, it is hard to come to a useful conclusion. C) If 
the problem declined, it might mean that the response was 
accidentally effective or some other factor was responsible. 
D) If the problem did not decline, then no useful conclusion 
is possible. Perhaps the implemented response is faulty and 
the original response would have been effective, or neither 
is effective. Unless the planned response was implemented, 
it is hard to learn from an impact evaluation.

Flowchart: Focus of Process and Impact Evaluations 
Process evaluation focus 
INPUTS 
 personnel 
 equipment 
 expenditures 
 other resources 
Process evaluation focus 
RESULTS 
 arrests 
 people trained 
 barriers installed 
 other tasks accomplished 
Impact evaluation focus 
OUTCOMES 
 crimes reduced 
 fear abated 
 accidents reduced 
 other reductions in problems 

Chart: Interpreting Results of Process and Impact Evaluations 
Response implemented 
as planned 
A. Evidence that the 
response caused 
the decline 
B. Evidence that the 
response was ineffective 
Response not implemented as 
planned 
C. Suggests that the response was 
accidentally effective or that other 
factors may have caused the decline 
D. Little is learned 
Problem declined 
and no other likely 
cause 
Problem did 
not decline 
Impact 
Evaluation 
Results 
Process Evaluation Results 


A response is a complex piece of machinery with a variety 
of components, any of which can go wrong (Step 45). A 
process evaluation examines which components were 
carried out successfully. The process evaluation checklist 
highlights the questions that you should ask. 

Scheduling of activities in a problem response is often 
critical. For this reason, it is useful to create a project 
timeline showing when key components were 
implemented. It is also useful to show when other 
unexpected events occurred and noting publicity so you 
can check for Anticipatory Benefits (Step 52). 

Though unexpected developments can force you to modify 
a response, some of these developments can be 
anticipated by understanding what can go wrong with 
responses. Some of the possible answers are as follows: 

1. You may have an inadequate understanding of 
the problem. You may have focused too little on 
repeat victims, for example. This can be caused by 
invalid assumptions about the problem or insufficient 
analysis (you did not look for repeat victimization, for 
example). If, while developing the response, you can 
identify weak spots in your analysis, then you can 
create contingency plans (a plan to address repeat 
victimization should this prove to be needed). 

2. Components of the project have failed. The
process evaluation checklist shows that there are
many potential points of failure. However, not all
components are equally important for success.

Further, it is sometimes possible to anticipate 
components with high failure rates. Citizen groups in 
general are quite variable in their ability to carry out 
tasks, for example. Building in redundancy or 
formulating backup plans can mitigate 
component failure. 

3. Offenders may react negatively to your 
response (Step 11). Some forms of negative 
adaptation can be anticipated and planned for. 
Sometimes geographical displacement locations can 
be identified before the response, for example, and 
advanced protective actions can be taken to 
immunize them. 

4. There are unexpected external changes that 
have an impact on the response. A partner 
agency's budget may be unexpectedly cut, for 
example, forcing it to curtail its efforts on the 
problem. As the problem will not dissipate on its own, 
the only recourse is to alter the plans. 

Process evaluations require information. This information 
will come largely from members of the problem-solving 
team, so it is important that they document their 
activities. Which activities they document and who 
records it in what detail are questions that should be 
resolved while planning the response. 

A Process Evaluation Checklist
Who is supposed to act? 
Police units Government partners Community groups Businesses Others 
What are they supposed to do? _______ 
Do they have the capability to act? 
Legal authority Local authority Resources Expertise 
When were they supposed to act? 
Date and times_____ Coordination with others _____ 
Who or what is supposed to receive action? 
People_____ Places_____ 
Was the action delivered appropriately? 
Type _____ Intensity_____ Duration_____ 
Are there back up plans for . . . 
Faulty plans ? Component failure ? Adaptation ? External changes ? 
 

47. Know how to use controls

You should address three questions when assessing 
a response: 

1. "What was the implemented response?" A process 
evaluation answers this question (Step 46). 

2. "Did the problem decline?" Comparing the level of the 
problem after the response to the level of the problem 
before answers this question. 

3. If the response declined, then ask "Did the response 
cause this decline, or was it something else?" There are 
usually many alternative explanations for the decline in 
the problem. 

Answering the third question requires the use of controls. 
The purpose of controls is to rule out alternative 
explanations. Different alternative explanations require 
different types of controls as described below: 

Changes in size. If there had been a decline in the 
number of tenants in an apartment building, we would 
expect the number of burglaries to decline because there 
are fewer potential victims. A reduction in targets is an 
alternative to the explanation that the drop was due to 
the intervention. To control for changes in size, divide the 
number of burglaries before and after the response by the 
number of occupied apartments before and after the 
response. In the table, what appears to have been a 
decline in burglaries was partially caused by the drop in 
occupied units. When this is accounted for, we still notice 
a response effect. If the time periods before and after are 
of substantially different lengths, we control for this by 
dividing again by the number of months before and the 
number of months after to get burglaries per occupied 
unit per month. 

Table: Using Rates to Control For Changes in Size
Table Headers: 6 Months Before, 6 Months After, Change 
Row Headers: Burglaries, Occupied Units, Burglaries/Occupied Unit 
Row 1: 41, 83, .494 
Row 2: 20, 73, .286 
Row 3: -21, -10, -.208 
 
Cycles of activity. Human activity oscillates over days, 
weeks, and months. Some of the most common cycles 
include commuting and attendance at school, work, and 
leisure, and seasons and holidays. Such cycles cause 
regular changes in problems. To control for cycles, 
compare the same part of the cycle before the response to 
the same part of the cycle after the response. 

Long-term trends in the problem. Problems may be 
getting worse (or better) before the response (Step 26). 
Without accounting for trends one could conclude that 
the response was responsible, when in fact this might 
have occurred anyway. There are two ways of controlling 
for trend. The first method is to measure the problem for a 
long period before the response so that any trend can be 
identified. Substantial deviations from the existing trend 
after the response are evidence of a response effect. 
Anticipatory effects (Step 52) are drops in the problem 
due to the response, but occurring before the response is 
fully implemented. These need to be distinguished from 
longer trends prior to implementation. 

The second method is to compare the people or places 
getting the response to a similar group of people or 
places not getting the response. This is called a control 
group or a comparison group. A control group must be 
similar to the response group with regard to the problem, 
but cannot receive the response. A control group tells you 
what would have happened to the response group, if the 
response group had not received the intervention. If the 
response group changes differently from the control 
group, this is evidence of a response effect. 

Other unexpected events. Many other things are 
changing as the response is implemented, one or more of 
which could have caused the decline in the problem. 
Instead of an accident-reduction response causing a 
decline in accidents on a road, for example, slow traffic 
from the road repairs, going on about the same time as 
the response, might have been the cause. The standard 
approach is to use a control group, as we discussed for 
examining trends. The control area is only useful if it is 
affected by the same factors as the response area. So, 
counting accidents on the response and control roads, 
both of which are influenced by the road repairs, could 
tell you whether the road repairs contributed to the 
decline in accidents. 

Change in problem measurement. A before-after 
comparison is only valid if the problem was measured in 
the same way before and after the response. 
Measurement differences can cause a perceived change in 
the problem. Use the same measurement procedures 
before and after. Before and after observations should 
occur at the same sites at the same times, watch the 
same things, and record things in the same way. Before 
and after photographs and videos should be taken in the 
same light from the same angles, at the same distance, 
and with the same size image area. Interviewers should 


be the same before and after, asking the same questions, 
in the same order. Examine official records to determine if 
recording practices are stable over time. 

Natural decline from an extreme high. Many 
problems are addressed because things have become 
extremely bad. So the response is implemented when the 
problem is abnormally high. But even a relatively stable 
problem will fluctuate. A problem that is now abnormally 
bad will return to its normal level, even if nothing is done 
(this is called "regression to the mean," and it applies to 
abnormal lows as well). Comparison area controls may 
not be useful here, if the response area is at a peak and 
the control area is not. Instead, examine the long-term 
fluctuation prior to the response to see if the problem was 
abnormally bad. 

The figure illustrates some of the uses of controls. Moving 
clockwise around this figure, panel A shows a 24-month 
time series with a response implemented in early 
November of the first year. There is a pronounced yearly 
cycle and a downward trend that are not due to the 
response. The spike in November following the response 
suggests that it backfired. 

Panel B shows a before-and-after comparison (the 
average of August-October, 2003 compared to the 
average of November 2003-January 2004) that suggests a 
worsening of the problem following the response. 

In panel C, a comparison area has been added. The 
immediate before-and-after comparison shows the 
response area doing better than its comparison area, but 
because of cyclical effects we would not have much 
confidence in these findings. Comparing the 3 months 
before the response to the same three months a year later 
accounts for the cyclical behavior of the crime series. 

But because some of the decline in both groups maybe 
due to the general downward trend, panel D provides a 
better picture of the impact of the response. Before the 
response, the area being treated is consistently worse 
than the comparison area. After the response, both do 
about the same. Also, the troublesome November spike 
seems to be unrelated to the response because it shows 
up in the control trend, too. The response seems effective, 
but is not dramatic, so its improvements were easily 
hidden by factors that need to be controlled - trends, 
cycles, and unexpected events. 

Graphs: Some Applications of Controls 
 
A. Monthly Time Series for Response Area Line Graph

B. Before 3 Month Average to After 3 Month Average 
Aug-Oct, 02 = 23.0
Nov.02-Jan 30 = 25.3

C. Before 3 Month Average to Same After 3 Month 
Aug-Oct, 02  = 23.0 (Response), 16.3 (Control)
Nov.02-Jan 30 = 25.3 (Response), 22.3 (Control)
Aug-Oct, 03 = 5.7 (Response), 8.3 (Control)

D. Monthly Time Series for Response and Control Areas Average Line Graph


48. Consider geographical and temporal displacement

Geographical displacement occurs when the 
intervention blocks crime or disorder opportunities 
at a facility or in an area, and offenders move to 
other facilities or areas to offend. Temporal displacement 
also stems from successful prevention, but in this case 
offenders shift offending in time to other hours or days. 

Offenders can find it difficult to move to some other 
location because easy crime or disorder opportunities are 
limited (Step 16). Targets may be concentrated at some 
places and not others (Step 16). Vulnerable potential 
victims can be found at some locations, but not others 
(Step 29). Some facilities have low behavioral controls, but 
others do not (Step 28). Opportunities that exist are either 
already hot spots or are hidden from offenders - either far 
away or not recognizable as fruitful places to offend. 

Offenders will not usually spend time searching far from 
their hot spot when it is suppressed. So, if offenders 
move, they are most likely to move to a place close to the 
original hot spot. The likelihood that offenders will move 
to an opportunity declines the further the opportunity is 
from the original hot spot, as illustrated in the figure. Also, 
not all spaces are suitable to offenders. Opportunities are 
not spread evenly across the map. 

In this map, the diamonds are places with characteristics 
like the original hot spot. Those closest to the original 
location are most likely to be affected most by 
displacement. In addition to distance, natural barriers to 
movement can limit displacement. In the figure, the river 
flowing northeast/southwest reduces the chances of 
displacement to the east. Knowing this, displacement 
countermeasures can be applied with the response at the 
most vulnerable locations. 

If geographical or temporal displacement occurs, it is most 
likely to shift crime to locations and times very similar to 
the locations and times affected by the prevention. Such 
shifts require less effort, learning, and risk for offenders 
than shifting to very different places and times. It is more 
likely that offenders will try to outwait the response, 
which explains Lawrence Sherman's finding that the 
effects of crackdowns decay. If offenders cannot outwait a 
response, it will be the most familiar locations and times 
that will have the greatest chance of receiving displaced 
crime. As Paul and Patricia Brantingham note, it is possible 
to predict the most likely areas for displacement. But this 
requires detailed knowledge of the crime opportunities in 
the current situation. 

If geographical displacement occurs, it can distort 
conclusions about effectiveness. Table 1 illustrates how 
this can happen. In this example there are three similar 
areas with equal numbers of crimes before treatment: (1) 
a treatment area; (2) an area adjacent to the treatment 
area; and (3) an area distant from the treatment area. The 
treated area has a decline of 25 crimes. However, the 
adjacent area has a 10-crime increase. This seems to 
suggest that if nothing had been done in the treatment 
area it too would have experienced a 10-crime increase. 
So the net reduction is 35 (the 25 crimes reduced in the 
treatment area and the 10-crime increase that 
was averted). 

Map: Decline of Geographical Displacement with Distance from Hot Spot Epicenter 


Table 1: Use of Adjacent and Distant Control Areas in Controlling for 
Geographical Displacement
Column Headers: Before, After, Difference, Estimated Net Effect
Row Headers: Treatment, Adjacent Area, Distant Area 
Before 
Treatment - 100 
Adjacent Area - 100 
Distant Area - 100 
After 
Treatment - 75 
Adjacent Area - 110 
Distant Area - 100 
Difference 
Treatment = -25 
Adjacent Area = +10 
Distant Area = 0 
Estimated Net effect 
Adjacent Area = -35 
Distant Area = -25 
 
But these extra 10 crimes could have been due to 
geographical displacement. One would be better off using 
the distant control area for comparison. As a control, the 
distant area suggests that if no treatment were 
implemented, crime would not have changed in either the 
treatment or the adjacent areas. The implication is that 
the treatment caused a 25-crime decline in the treatment 
area, but a 10-crime increase in the adjacent area 
(displacement), for a combined reduction of 15 crimes. 
Though effective, the program is not as effective as 
originally estimated. Step 51 describes formulas to take 
account of displacement when assessing effectiveness. 

Try to select two comparison areas as part of evaluations: 
one near the treatment area that has similar crime 
opportunities to detect geographical displacement (and 
diffusion, Step 51), and the other to serve as a control 
area. The control area should be protected from 
displacement contamination by distance or some other 
barrier (e.g., a highway or river). Valid selection of control 
and displacement areas requires you to have some idea of 
offenders' normal movement patterns, as the control area 
needs to be outside their roaming territory while the 
displacement area should be within it. 

Temporal displacement may be easier for offenders than 
geographical displacement because it requires less effort. 
Temporal displacement can occur within a 24-hour day, if, 
for example, the prevention is restricted to certain times 
but leaves other times unprotected. It can also occur over 
a week. Or it can occur over longer periods. 

If the evaluation compares times with a prevention 
response to times without a prevention response, 
contamination of temporal controls can take place. In 
Table 2, a treatment takes place on Saturday and Sunday. 
The average number of crimes on these days dropped by 
25 crimes after treatment, while crimes on Mondays and 
Fridays increased by 10. Was this due to temporal 
displacement? Midweek days may be more valid controls 
because they have less in common with weekends than 
do Mondays and Fridays. 

Waiting out the prevention is a common form of temporal 
displacement. Enforcement crackdowns are particularly 
vulnerable to this form of time shifting because they are 
temporary by definition. If an intervention can be 
maintained (unlike a crackdown), then offenders cannot 
wait it out. They then face the difficult option of moving 
to less attractive places or targets or undertaking new 
tactics or other crimes. If these options are too difficult, 
unrewarding, risky, or otherwise unattractive they may 
commit fewer offenses. 

Read More: 

Brantingham, Paul and Patricia Brantingham. (2003). 
"Anticipating the Displacement of Crime Using the 
Principles of Environmental Criminology." Crime 
Prevention Studies, volume 16. Monsey, NY: Criminal 
Justice Press. 

Eck, John (2002). Assessing Responses to Problems: An 
Introductory Guide for Police Problem-Solvers. 
Washington, DC: U.S. Department of Justice, Office of 
Community Oriented Policing Services. (Accessible at: 
www.popcenter.org and www.cops.usdoj.gov ). 

Table 2: Using Days of the Week to Control for Temporal Displacement
Table Column Headers: Days of week, Before, After, Difference, Estimated Net Difference
Table Row Titles: Treatment, Adjacent Area, Distant Area 
Treatment 
Sat & Sun, 100, 75, -25, n/a
Mon & Fri, 100, 110, +10, -35
Tues-Thurs, 100, 100, 0, -25

 

49. Examine displacement to other targets, tactics, and crime types

In addition to geographical and temporal displacement, 
offenders can switch targets, change their tactics, or 
change crimes. 

Target displacement involves offenders shifting from newly 
protected targets to other targets. In 1970, when steering 
column locks became required in all new cars sold in 
Britain, thefts of new cars dropped from 20.9 percent of 
all cars stolen in 1969, to 5.1 percent in 1973. However, 
the overall theft rate of automobiles stayed roughly 
constant because offenders switched from the newer, 
protected, vehicles to older, unprotected, vehicles. This is 
one of the few documented cases where displacement 
wiped out most prevention gains, at least in the short run. 
Over a longer period, these devices appeared to have 
curbed theft for temporary use. As this case illustrates, it is 
easy for offenders to switch to very similar targets. Target 
displacement is less likely when the alternative targets are 
unlike the old targets. 

Step 42 shows how geographical or temporal 
displacement can contaminate control groups. If the 
evaluation of a prevention effort uses a target control 
group, then a similar form of contamination can take 
place. Imagine a response to curb theft of purses from 
women over 60 years old in a shopping center. To 
estimate what the trend in elderly purse theft would be if 
nothing had been done, the theft of purses from middle-
aged women of 45 to 59 is measured. If, unknown to us, 
the thieves displaced from the protected older women to 
unprotected middle-aged women, we would conclude that 
purse theft would have gone up without a response. 
When we compare this control target group change to the 
treatment group change we would mistakenly inflate the 
treatment effectiveness. A better control group might be 
even younger women shoppers (ages 30 to 44, for 
example), or even better, wallet theft of male shoppers. 
Though neither of these alternatives is perfect, they are 
improvements because one would expect far less 
displacement to dissimilar targets. Or, select another 
shopping district as a control area - in which case you 
would have to guard against geographical diffusion or 
displacement contamination, Steps 48 and 51. 

Tactical displacement occurs when offenders change their 
tactics or procedures. They might use different tools to 
defeat better locks, for example. Or computer hackers 
might alter their programs to circumvent improved 
security. In medicine, some bacteria can mutate quickly so 
a drug that is effective against one form of the bacteria 
becomes less effective as mutant strains become more 
prevalent. One way of countering this is to use broad-
spectrum treatments that are effective against a wide 
range of mutations. Similarly, "broad spectrum" responses 
protect against existing methods used by offenders and 
many modifications of these tactics. Broad-spectrum 
interventions require offenders to make big changes in 
their behavior that they may not be able to do. Paul 
Ekblom describes attempted tactical displacement 
following the installation of barriers in British post offices 
to prevent "over-the-counter" robberies; some offenders 
tried using sledge-hammers. This change in tactics was 
not particularly successful, however, and displacement was 
limited. These barriers are an example of a 
broad-spectrum intervention as they were able to defeat 
new tactics. 

Switching crime type is another type of displacement you 
should look for. Offenders might switch from vehicle theft 
to vehicle break-ins, or carjacking. We sometimes 
evaluate responses to one type of crime by comparing the 
trend in a similar type of crime that did not get a 
prevention response. For example, we might select theft 
from vehicles as a control in the evaluation of a theft of 
vehicles intervention. 

The same principles of contamination and protection 
apply to tactical and crime type displacement as we found 
with other forms of displacement. If the tactic or crime 
type is very similar to the tactic or crime type being 
addressed, then displacement could contaminate these 
controls. Dissimilar tactics or crime types are less likely to 
suffer contamination. But if they are too dissimilar it is not 
a useful control. 

There is no perfect solution to this problem and 
compromises must be struck. The consequence is that it is 
often difficult to know if displacement is occurring and 
difficult to judge the effectiveness of the intervention. 
Compounding these difficulties is that multiple forms of 
displacement can occur simultaneously. Indeed, 
sometimes one form of displacement will necessitate 
another form as well. Target displacement may require a 
change in tactics, and if the new targets are not in the 
same places as the old targets, geographical displacement 
will occur, too. 


You cannot find displacement unless you look for it. This 
means that you should examine a problem closely and 
imagine the most likely forms of displacement. Are there 
other opportunities for crime or disorder that are similar 
to the opportunities your efforts are trying to block? Will 
your offenders easily discover these opportunities? 
Looking for displacement opportunities prior to finalizing 
a response gives you two advantages. First, you can 
develop measures for detecting it should it appear. More 
important, you may be able to develop counter-measures 
that prevent displacement. 

Read More: 

Ekblom, Paul (1987). Preventing Robberies at Sub-Post 
Offices: An Evaluation of a Security Initiative. Crime 
Prevention Unit Paper 9. London: Home Office. 

Webb, Barry (1994). "Steering Column Locks and Motor 
Vehicle Theft: Evaluations from Three Countries". Crime 
Prevention Studies, volume 2, Ronald Clarke. Monsey, NY: 
Criminal Justice Press. (Accessible at: www.popcenter.org). 

A study of target displacement: helmet laws and the reduction in motorcycle theft 

In Germany (as elsewhere) the enactment of helmet laws was followed by large reductions in thefts of motorcycles. 
After the laws were brought into place in 1980, offenders wanting to steal a motorbike had to bring a helmet or 
they would be spotted quickly. The figure shows that by 1986 thefts of motorbikes had dropped to about one-third 
of their level in 1980, from about 150,000 to about 50,000. (The gradual decline probably reflects stronger 
enforcement and growing knowledge about the requirement.) This fact suggests that motorbike theft has a much 
larger opportunistic component than anyone would have thought. The existence of excellent theft data in Germany 
allowed researchers to investigate whether the drop in motorcycle theft had resulted in target displacement to theft 
of cars or bikes, other forms of personal transportation. 

The other two lines show the national totals for car and bike thefts during the same years. These provide some 
limited evidence of displacement in that thefts of cars increased by nearly 10 percent between 1980 and 1986, from 
about 64,000 to 70,000. Thefts of bicycles also increased between 1980 and 1983, but by the end of the period had 
declined again to a level below that for 1980. Altogether, it is clear that at most only a small proportion of the 
100,000 motorbike thefts saved by the helmet laws were displaced to thefts of other vehicles. 
A little thought shows why this may not be surprising. Motorbikes may be particularly attractive to steal. They are 
much more fun to ride than bikes for the young men who comprise most of the thieves. Even if the intention is 
merely to get home late at night, a motorbike offers significant advantages, especially if the distance is more than a 
few miles. Motorbikes may also be easier to steal than cars since the latter have to be broken into before they can 
be started. Like bikes, cars also offer less excitement than motorcycles and they may require more knowledge 
to operate. 

Source: Mayhew, Pat and colleagues (1989). Motorcycle Theft, Helmet Legislation and Displacement. Howard Journal 
of Criminal Justice 28:1-8. 


50. Watch for other offenders moving in

Three principles of this manual are: (1) it takes more 
than offenders to create problems; (2) people cannot 
offend if there is no opportunity structure to support 
this behavior; and (3) altering the opportunity structures 
can dramatically reduce problems. It follows that 
responses focusing on only removing offenders have 
limited effects on problems. After some offenders are 
removed, there may be a decline in the problem for a 
short time, then either the old offenders return to take 
advantage of the opportunities, or new offenders start 
taking advantage of them. This is sometimes called 
perpetrator displacement. Natural replacement of 
offenders can be slow, particularly if the opportunities are 
obscure. But if someone discovered the crime 
opportunities in the past, others will rediscover them in 
the future. And if the old offenders were removed through 
imprisonment, some may return to take advantage of the 
opportunities upon their release. 

New offenders attracted by opportunities might contribute 
to long-term crime cycles. Bank robberies in parts of the 
United States may be an example of this. For a few years 
there will be a large number of these crimes and then 
they will decline for several years, only to surge again 
later to start the cycle over again. One hypothesis for 
these cycles is that during peak robbery years, banks 
begin instituting a host of preventive measures and most 
offenders are caught and imprisoned. These efforts drive 
bank robbery down. After several years with few bank 
robberies, bank security becomes lax and the 
opportunities for bank robbery increase. Then new 
offenders start to take advantage of the lower security, 
beginning a new wave of robberies and prevention. This 
hypothesis draws attention to the fact that it takes more 
than enforcement to be effective, and prevention gains 
must be maintained to stay effective. 

In fact, it is quite common to read descriptions of 
problem-solving efforts that begin with a description of 
failed enforcement efforts. In every situation either old 
offenders keep coming back or new offenders have 
replaced them. There are three ways in which new people 
are exposed to offending opportunities: 

1. They are exposed to them through their normal daily 
routines. Police arrest young men stealing items from 
unlocked cars in a city center, for example, but 
unlocked cars with things in them remain there. Of 
the many people who use the city center on a daily 
basis, a few will notice these cars and try their hand 
at theft. If successful, some of these individuals will 
continue to steal from cars. 

2. They are exposed to crime opportunities through 
informal networks of friends and acquaintances. 
People already experienced in taking advantage of an 
opportunity to commit crime or disorder may invite 
others in to help them or enjoy the experience. Since 
we are seldom 100 percent successful at removing all 
the offenders for long periods, there are usually many 
people around who can introduce new people to 
the opportunities. 

3. They discover offending opportunities through 
recruitment. A criminal receiver may employ new 
burglars if the old ones can no longer supply him with 
goods. If prostitution is organized, then a pimp may 
recruit new prostitutes to fill the jobs left vacant by 
the former prostitutes. Gangs may bring in new 
members to replace old ones. It has been suggested 
that adult drug dealers, faced with stiffer penalties for 
drug convictions, started hiring juveniles to carry out 
the riskiest tasks because the penalties for juveniles 
caught with drugs were much less than for adults. 

How do you find out if offenders are moving in? The most 
straightforward method is to compare the names of 
offenders associated with the problem before the 
response to the names of offenders associated with the 
problem after the response. If the names are different, 
then offenders may be moving in. The difficulty with this 
approach is that a complete roster of the offenders 
involved is seldom available. So it is not clear if the new 
names are really new offenders, or if they have been part 
of the problem for some time, but have only recently 
been discovered. 

Offender interviews can also be helpful. Offenders may 
tell you when they became involved in the problem, how 
they became involved, and who else is involved. They can 
also provide information on tactical and other forms of 
displacement. However, offenders can be uncooperative 
and unreliable (Step 10). 

Sometimes detailed examination of the methods used to 
commit crimes can provide insights into whether new 
offenders are involved. If the tactics are radically different 
than those used earlier, there is a possibility that new 
offenders are working. However, it is also possible that 
the old offenders have switched tactics. 


Read More: 

Matthews, Roger (1997). "Developing More Effective 
Strategies for Curbing Prostitution" Situational Crime 
Prevention: Successful Case Studies (2nd ed.), Ronald 
Clarke. Monsey, NY: Criminal Justice Press. 

Combining Crackdowns with Environmental Modifications: 
Controlling "Away Day" Prostitutes in Finsbury Park 

Roger Matthews describes a London prostitution problem in the Finsbury Park neighborhood of London. Repeated 
crackdowns by the police over many years had failed to control the prostitution market as the prostitutes simply 
returned to the same area. When crackdowns were combined with street barriers to make it difficult for men to find 
prostitutes by driving around the area in their cars, the level of prostitution activity dropped dramatically. Matthews 
suggests that it was the combination of strategies - offender removal through enforcement and opportunity blocking 
through street barriers - that was responsible for the decline. One important reason why these interventions were 
successful was that the prostitutes were not deeply committed to this way of earning a living. Few of them were 
addicts or under the control of pimps. In fact, the most common reasons they gave for working as prostitutes was 
that they could earn more money than other forms of work, they enjoyed the independence and enjoyed meeting a 
variety of men. Many of them came to Finsbury Park from outlying areas on cheap rail tickets. Together with other 
women, they rented rooms in one of the many boarding houses or residential hotels in the area, or they conducted 
business in the cars of clients. When not working as prostitutes, many of them worked as barmaids, go-go dancers or 
as store clerks. Their relatively light commitment to prostitution and their alternative ways of making money might 
help explain why the researchers could find little evidence of displacement of the Finsbury Park prostitutes to other 
nearby areas in London. 


51. Be alert to unexpected benefits

You can drastically underestimate the effects of your 
intervention if you do not take account of diffusion 
of benefits (Step 13). You may conclude that the 
intervention is not worth the effort or that it failed to 
suppress the problem. This is particularly true when 
diffusion contaminates your control group. 

Control groups show what would have happened to 
problems if you did nothing (Step 47). They need to be as 
similar to the treatment group as possible, but they must 
not be influenced by the treatment. If prevention diffuses 
into the control area, you will get the misleading 
impression that things would have gotten better if no 
response had occurred. This invalid conclusion will cause 
you to underestimate the effectiveness of your program. 
(See Step 48 for related issues with displacement.) 

Kate Bowers and Shane Johnson suggest two ways to 
select control areas when displacement or diffusion of 
benefits are possible. The first is to create two concentric 
zones around the treatment area. Prevention may diffuse 
into the adjacent buffer zone but does not contaminate 
the outer control area. This is feasible if the control and 
treatment areas are very similar and diffusion or 
displacement does not reach the control zone. If these 
conditions are not met, then option 2 should be used. 
Here a displacement/diffusion sites near the treatment 
area are used, but the control areas are widely separated 
from the treatment and diffusion/displacement areas. 
Controls are selected specifically for their similarity to and 
isolation from the treatment area. Multiple control areas 
can be selected and their crime rates averaged. 

The figure shows an example of option 2. Imagine a 
response to the theft from vehicles in downtown Charlotte 
parking lots (Step 27). One theft hot spot site is selected 
for a response. The neighboring hot spots are good 
diffusion/displacement sites. Earlier analysis showed that a 
rail line through these lots facilitated the problem, so a 
third hot spot lot to the south and west on this rail line is 
also a useful diffusion-displacement site. Control lots are 
not on the rail line and far enough from the response site 
that diffusion and displacement are unlikely. 

To determine the overall effect of the response on the 
problem (including any diffusion or displacement effects) 
you need to answer four questions. Each question has a 
simple formula. The letters in the formulas follow 
this pattern. 

 R is the number or rate of crimes in the response area. 
 D is the number or rate of crimes in the 
displacement/diffusion area. 
 C is the number or rate of crimes in the control area. 
 The subscripts, a and b, indicate when crime is 
counted; after or before the response began. For 
example, Ra is the rate of crimes in the response area 
before the response was implemented, and Cb is the rate 
of crimes in the control area after the response 
was implemented. 

1. Did the problem change from before to after 
the response? Subtract the crime in the treatment 
area before the response from the treatment area 
after the response to get the Gross Effect (GE): 

GE = Rb - Ra 

A positive number indicates a decline in the problem. 
Zero indicates no change. And a negative number 
indicates things got worse. 

2. Was the response a likely cause of the change? 
Browers and Johnson suggest looking at the difference 
in the ratios of the treatment area to the control area 
before and after; that is divide the before response by 
the before control minus the after response divided by 
the after control. This is the Net Effect (NE): 

Rb Ra 
NE = -
Cb Ca 

If the net effect is close to zero, the response probably 
was ineffective, and if NE is negative the response may 
have made things worse. In either case, displacement 
and diffusion are irrelevant so you can stop with the 
answer to this question. But if NE is positive, there is 
reason to believe the response may have caused the 
improvement. This raises the possibilities of diffusion 
and displacement. So you need to answer the 
next question. 


3. What is the relative size of the displacement or 
diffusion? Bowers and Johnson propose the 
Weighted Displacement Quotient (WDQ) to 
measure this: 

Da Db
Ca Cb
WDQ = 
Ra Rb
Ca Cb

Da is the crime rate in the diffusion/displacement area 
after the program and Db is the crime rate in this area 
before the program. The bottom term (denominator) 
is a measure of the effectiveness of the response, 
relative to the control. An effective program will 
produce a negative number in the denominator. The 
top term (numerator) shows the relative amount of 
diffusion or displacement. The numerator is negative 
when diffusion is present and positive when 
displacement is present. If it is near zero, neither is 
present and the WDQ is zero (so you can skip 
question 4). If the WDQ is positive, there is diffusion 
(remember, a ratio of two negative numbers is 
positive), and if it is greater than one, then the 
diffusion effect is greater than the response effect. If 
the WDQ is negative, there is displacement. When the 
WDQ is between zero and negative one, displacement 
erodes some, but not all, of the response effects. 
Theoretically, the WDQ could be less than negative 
one, indicating the response made things worse. 
However, research suggests that this is an 
unlikely occurrence. 

4. 
What is the Total Net Effect of the response 
(including diffusion and displacement)? Bowers 
and Johnson suggest using the following formula to 
calculate the TNE: 

TNE= Rb -Ra Ca Ca

+ 

Db -DaCb 

Cb 

The first part shows the effect of the response in the 
response area. The more effective the treatment, the 
bigger this term. The second part shows the level of 
diffusion or displacement. It will be positive when 
there is diffusion and negative when there is 
displacement. The more positive the TNE, the more 
effective the response. 

Read More: 

Bowers, Kate and Shane Johnson (2003). "Measuring the 
Geographical Displacement and Diffusion of Benefit 
Effects of Crime Prevention Activity." Journal of 
Quantitative Criminology 19(3):275-301. 

Map: Selecting Control and Diffusion/Displacement Sites


52. Expect premature falls in crime

Offenders often believe that prevention measures 
have been brought into force before they actually 
have been started. This leads to what has been 
called the "anticipatory benefits" of prevention. Though 
these anticipatory effects can occur by accident, the police 
can make deliberate efforts to create or intensify them. To 
do so successfully, police must have useful insight into 
how offenders perceive the situation and have methods 
for deceiving offenders as to the true nature of 
the intervention. 

Martha Smith and her colleagues found evidence of 
anticipatory benefits in 40% of situational prevention 
studies whose data could have revealed such benefits. 
They have suggested six possible explanations for 
observed anticipatory benefits: 

1. Preparation-anticipation effects occur when 
offenders believe the program is operational before it 
is actually working. For example, a property-marking 
program may be announced to the public, but 
residents have not yet been mobilized, or closed 
circuit television cameras may be installed but not 
yet monitored. 

2. Publicity/disinformation effects occur when 
offenders believe covert enforcement exists as the 
result of publicity or rumor. Offenders' perception can 
be manipulated, at least in the short run, through 
disinformation. Rather than disinformation, targeted 
communications can sometimes be effective. A Boston 
project to reduce youth homicide used direct 
communications with potential offenders to warn 
them that certain specified behaviors would result 
in crackdowns. 

3. Preparation-disruption effects occur when 
preparation for the prevention program causes 
surveillance at the prevention sites. Surveys of 
residents might alert offenders. Problem-solving 
projects can create anticipatory responses during their 
analysis stage if there is considerable visible enquiry 
in the community. In the late 1980s as part of the 
analysis of a burglary problem, members of the 
Newport News Police Department conducted door-todoor 
surveys in a high burglary neighborhood. This 
may have contributed to the subsequent fall in 
burglaries. In their review of effective policing 
strategies, Sherman and Eck noted that door-to-door 
police contacts have generally been found to have a 
crime reduction effect. 

4. Creeping implementation occurs when parts of the 
response are put into effect before the official start 
date. The evaluator may use June 1st as the beginning 
of the full program, but offenders detect staged 
implementation in the weeks leading up to June 1, 
and change their behavior accordingly. 

5. Preparation-training effects occur when planning, 
training, and surveys make the public or police better 
prepared to address problems and they use this new 
knowledge prior to the program going into effect. A 
coordinated multi-business anti-shoplifting program, 
for example, may be scheduled to begin on a 
particular date, but the discussions and training of 
employees makes them more attentive prior to 
that date. 

6. Motivation of officers or public occurs for similar 
reasons as preparation training, except the people 
involved are more highly motivated rather than better 
equipped. The higher motivation leads to improved 
performance in advance of response implementation. 

Using a timeline to carefully document when pieces of the 
response were implemented is helpful for showing that an 
anticipatory effect is plausible (see Step 46). 

Smith and her colleagues also identified four distinct 
circumstances that masquerade as anticipatory effects, but 
are really the results of misinterpretation or 
incomplete analysis: 

1. Seasonal changes can create pseudo anticipatory
effects when an intervention begins shortly after 
seasonal turndown in crime. Controlling for
seasonality (Steps 26 and 47) can eliminate 
this problem.

2. Regression effects refer to natural declines in crime 
from extreme highs that occur even if nothing is done 
(Step 47). If a crime trend for a problem has just 
dropped due to a regression effect and a prevention 
program is implemented, the natural decline will look 
like an anticipatory effect. Examining the long-term 
average crime level (Step 26) prior to the response, as 
suggested in Step 47, can reveal a regression effect 
masquerading as an anticipatory effect. 


3. If a crime type (A) has been over-recorded by 
changing the classification of another crime, it is 
possible to get what looks like an anticipatory effect. 
This might occur if one type of crime was inflated in 
order to gain funding to address that type of crime, 
and then following the receipt of funding, the 
classification was changed back to normal. This bogus 
anticipatory effect can be detected by looking at 
opposite trends in the other crime. Finding two similar 
crimes that have opposite trends provides a clue that 
classification changes may be responsible. 

4. Smoothing data (Step 26) to reveal a trend masked 
by random variation can produce results that look like 
anticipatory effects. The wider the moving average (5 
periods rather than 3, for example) and the bigger 
and more abrupt the decline in crime following the 
intervention, the more likely smoothing could create a 
pseudo anticipatory effect. Comparing smoothed and 
unsmoothed data will reveal this pseudo 
anticipatory effect. 

Read More: 

Sherman, Lawrence and John Eck. 2002. Policing for 
Crime Prevention. Pp. 295-329 in Evidence-Based Crime 
Prevention, edited by Lawrence Sherman and colleagues. 
New York: Routledge. 

Smith, Martha and colleagues (2002). Anticipatory 
Benefits in Crime Prevention. In Analysis for Crime 
Prevention. Crime Prevention Studies, Volume 13. Monsey, 
New York: Criminal Justice Press. 

Anticipatory Effects of Publicity 
Paul Barclay and colleagues evaluated the effects of bike patrols on auto theft from a large commuter parking lot outside 
Vancouver, British Columbia. Vehicle theft dropped after the response, but it had been dropping for several weeks prior to the bike 
patrols, since the implementation of a publicity campaign that preceded the bike patrols. In this case, an anticipatory effect may 
have added a great deal to the overall effectiveness of the patrols. Though a moving average was used to smooth out random 
variation, the drop in thefts between the beginning of the publicity and the beginning of the bike patrols is too large to be due to 
data smoothing. 

Line graph of reported vehicle thefts in a two week period

Source: Barclay, Paul and colleagues (1996) "Preventing Auto Theft in Suburban Vancouver Commuter Lots: Effects of a 
Bike Patrol." Crime Prevention Studies, volume 6, Monsey, NY: Criminal Justice Press. 


53. Test for significance 

How do you know that a response caused a problem 
to decline? Most problems vary in intensity, even 
when nothing is done about them. For example, on 
average there are 32 vehicle thefts per week in a 
particular city center, but seldom are there weeks with 
exactly 32 thefts. Instead, 95 percent of the weeks have 
between 25 and 38 thefts, and in 5 percent of the weeks 
fewer than 25 or more than 38 thefts are recorded. Such 
random variation is common. A reduction in vehicle thefts 
from an average of 32 per week to an average of 24 per 
week might be due to randomness alone, rather than a 
response. Think of randomness as unpredictable 
fluctuations in crime due to a very large number of small 
influences, so even if the police do nothing crime 
will change. 

A significance test tells us the chance that a change in 
crime is due to randomness. A significant difference is 
one that is unlikely to be caused by randomness. It is 
harder to discern whether a small difference is significant 
than it is to find significance in a large difference. It is 
also harder to find a significant difference in a normally 
volatile crime problem, even if the response is effective. 
And it is harder to find significance if you are only looking 
at a few cases (people, places, events, or times) than if 
you are looking at many (again, even if the response was 
effective.) You cannot control the size of the difference or 
the volatility of the problem, but you may be able to 
collect data on more cases. 

Bar Graph A: Clear Difference

Basr Graph B: Ambiguous Difference

Bar Graph C: Probably Random Difference

Consider the following common situation. You want to 
determine if crime dropped in an area following a 
response. You have a number of weeks of crime data 
prior to the response and a number of weeks of data for 
the same area following the response. You calculate the 
average (mean) number of crimes per week for each set 
of weeks and find that crime dropped. 

The figure shows three possible results. In each panel 
there are two distributions, one for the weeks before the 
response and one for the weeks after the response. The 
vertical bars in each chart show the proportion of weeks 
with 0, 1, 2, or more crimes (for example, in the top chart, 
6 crimes occurred in 20 percent of the weeks after the 
response). In panel A, the distributions barely overlap 
because the difference in means is large and the standard 
deviations of the two groups are small (see Step 22). 
Even with a few weeks of data, a significance test could 
rule out randomness as a cause. In panel B, there is 
greater overlap in the distributions, there is a smaller 
difference in the means, and the standard deviations are 
larger. It takes many more cases to detect a non-random 
difference in situations like this. In panel C, there is 
almost complete overlap, the mean difference is even 
smaller, and the standard deviations are even larger. Only 
a study with a very large number of cases is likely to find 
a significant difference here. The moral is that the less 
obvious the crime difference, the more cases you will need 
to be sure randomness was not the cause of 
the difference. 



Probability theory lets us use the mean, standard 
deviation, and number of cases to calculate the 
probability that randomness is the cause of the difference. 
If there is less than a 5 percent chance that the problem's 
change was due to random fluctuations, we reject the 
explanation of randomness as a cause of the change. 
Here, 5 percent is called the significance level. In short, 
because the probability that randomness is the cause is 
below the significance level (5 percent) we "bet" that 
something other than randomness caused the change. 
Though 5 percent is a conventional significance level, you 
can pick a more stringent level, such as 1 percent. The 
more stringent the significance level you select, the 
greater the likelihood you will mistakenly conclude that 
the response was ineffective when it actually worked. 
This type of mistake is called a "false negative" (see Step 
37). You might pick a stringent significance level if the 
cost of the response is so high that you need to be very 
certain it works. 

Occasionally, analysts use a less stringent significance 
level, such as 10 percent. The less stringent the level you 
pick, the greater the possibility that you will mistakenly 
endorse a response that has no effect. This type of error is 
called a "false positive" (see Step 37). You might want to 
pick a less stringent level if the problem is serious, the 
measures of the problem are not particularly good, and 
you are very concerned about accidentally rejecting a 
good response. 

There are two ways of using significance levels. In the 
discussion above, we used them as rejection thresholds: 
below the level you reject random chance and above the 
level you accept it as the cause. Always pick the 
significance level before you conduct a significance test to 
avoid "fiddling" with the figures to get the 
desired outcome. 

It is better to use the significance level as a decision aid, 
along with other facts (problem seriousness, program 
costs, absolute reduction in the problems and so forth), to 
make an informed choice. Many sciences, such as 
medicine, follow this approach. If you follow this 
approach, use a p-value instead of the significance test. 
The p-value is an exact probability that the problem's 
change is due to chance. So a p-value of 0.062 tells you 
that there is about a 6 percent chance of making a false-
positive error by accepting the response. This can be 
roughly interpreted to mean that in 100 such decisions, 
the decision to reject randomness in favor of the response 
will be wrong about six times. Whether you or your 
colleagues would take such a bet depends on a 
many things. 

It is important to distinguish between significant and 
meaningful. "Significant" means that the difference is 
unlikely to be due to chance. "Meaningful" means the 
difference is big enough to matter. With enough cases, 
even a very small difference is significant. But that does 
not mean it is worthwhile. Significance can be calculated. 
Meaningfulness is an expert judgment. 

The investigation of randomness can become very 
complex, as there are many different types of significance 
tests for many different situations. There are some very 
useful websites, as well as books, which can help you to 
choose among them, and there are many statistical 
software programs that can make the required 
calculations. But if there is a great deal riding on the 
outcome of a significance test, or a p-value, and you are 
not well educated in probability theory or statistics, you 
should seek expert help from a local university or other 
organizations that use statistics on a regular basis. 

Read More: 

Crow, Edwin and colleagues (1960). Statistics Manual. 
New York: Dover. 

Website with many useful statistical links 

www.prndata.com/statistics_sites.htm 


54. Tell a clear story

The purpose of your work is to help people make 
better decisions. To assist decision-makers, you must 
tell a clear story that leads from an important 
question to possible answers and then to effective 
actions. To communicate effectively you need to know 
who your audience is and the questions they want 
answered. Your story has to address their particular needs. 
This story can be told in a written report or in an oral 
presentation (see Step 58). 

Do not simply recount what you did to detect, analyze, 
respond, or assess. This is tedious and does not help 
people make actionable decisions from your work. You 
must translate your analytical work into a story that 
addresses the needs of your audience. 

Your work can help answer four basic questions. These 
questions correspond to the stages of the SARA process: 

1. What is the nature of the problem? (Scanning) 
2 .What causes the problem? (Analysis) 
3. What should be done about the problem? (Response) 
4. Has the response brought about a reduction in the 
problem? (Assessment) 

Clearly, these questions must be made more specific 
based on the facts of the problem being examined. Local 
residents, for example, might complain about late night 
noise and finding litter along their street. Instead of the 
general scanning question, you could develop a set of 
specific questions, based on the CHEERS test (Step 14): 

 What is the nature of the noise incidents? (Events) 

 In what ways are these incidents similar? (Similarity) 

 Are there recurring instances of late-night noise and 
litter that disturb residents? (Recurring) 

 Who, when, and where do these incidents occur? 
(Community) 

 How do these incidents disturb people? (Harm) 

 Who expects the police to address the problem? 
(Expectation) 

Answering the general question - What is the nature of 
the problem? - requires you to answer a set of more 
specific questions. 

Your first task in telling a coherent story is to decide 
which kind of question you are seeking to answer. Next, 
you should try to structure your account around the basic 
theories and approaches described in this manual (e.g., 
the CHEERS test, the crime triangle, or the 80-20 rule). 
These are frameworks. A framework is a general "story 
shell" linking multiple interacting factors and that can be 
applied to a variety of problems. Your choice of 
frameworks depends on the problem, your findings, and 
the needs of decision-makers. Be sure there is a logical 
flow from the basic question, through the framework and 
findings, to the answers. Check for gaps in logic. Now 
outline your story. There are four basic story outlines that 
can guide your work. The details of the story will depend 
on the specifics of your problem. 

Do not stick religiously to these outlines; we provide them 
as a starting point to prompt ideas. Instead, tailor them 
to the amount of time you have and, above all, to the 
concerns of the people whom you are addressing. Try to 
anticipate their questions, and modify the appropriate 
outline accordingly. Though we have used technical terms 
from this manual in these outlines, you may need to use a 
common vocabulary in your presentation. If your audience 
is not already familiar with the terminology of problem 
analysis, you probably should use it sparingly, or not at all. 

Four Story Outlines 

1: What is the nature of the problem? 

A. Organizing framework - e.g., CHEERS elements. 
B. Systematic description of evidence about problem type 
and existence: 

 What is the nature of the events? 
 In what ways are these events similar? 
 How often do these events recur? 
 When and where do these events occur? 
 Who is harmed by these events, and how? 
 Who expects the police to address the problem? 

C. Implications for analysis and collaborative problem 
solving: 

 Questions that need answering. 
 Definitional and measurement issues. 
 Partners who need to become involved. 

D. Summary. 


2: What causes the problem? 

A. Organizing framework for problem - e.g., problem 
analysis triangle. 
B. Systematic description of problem answering the 
following questions: 

 Who are the offenders? 
 Who or what are the targets? 
 At what places and times does the problem occur? 
 What brings the offenders and targets together at the 
same places? 
 Why don't others step in to prevent these encounters? 
 What facilitates or inhibits the problem? 

C. Implications for general form of responses that fit 
the information: 

 Offender access or control. 
 Victim/target behaviors or protection. 
 Facility access or management. 

D. Summary. 

3: What should be done about this problem? 

A. Organizing framework for response - e.g., situational 
crime prevention: 

 Offenders. 
 Targets/victims. 
 Places. 

B. Systematic description of response strategy: 

 Increasing risk or effort. 
 Decreasing reward, excuses, or provocations. 
 Who will carry out actions, when, and where? 
 Additional resources required. 

C. Implications and anticipated outcomes: 
 Direct results. 
 Displacement. 
 Diffusion. 
 Other side effects. 
 How evaluation should be conducted. 

D. Summary. 

4: Has the response reduced the problem? 

A. Organizing framework - e.g., principles of evaluation. 
B. Systematic description of evaluation: 

 Was the response implemented as planned? 
 Did the problem change? 
 Why it is likely that the response was a direct cause of 
change. 
 The magnitude of displacement, diffusion and other 
side effects. 
C. Implications for further action: 
 Is this problem solving effort complete? 
 What further actions are necessary? 
 Should further analysis be conducted? 
 Should the response be changed? 

D. Summary. 


55. Make clear maps

Maps have an important role in telling compelling 
stories about problems. But they need to be clear 
to accomplish this. That is, maps must contain as 
much relevant information as possible and no irrelevant 
information. There are a number of guides to good 
cartographic principles available (see box and Read More). 

We will illustrate the use of maps to tell stories with a set 
of maps from a problem-solving project undertaken by the 
Norwegian Police. Figures 1 and 2 illustrate how maps 
can be used to describe problems and solutions. 
Johannes Knutsson, of the National Norwegian Police 
Academy, and Knut-Erik Svik, of the Vestfold Police 
District, were attempting to address a problem of illegal 
("gypsy") cabs in a small coastal town of Tnsberg 
(population 36,000). On weekends the 30 drinking 
establishments draw large crowds and people move back 
and forth across a highway, so the highway is closed on 
Friday and Saturday nights. A parking area is also closed. 
However, legal taxis and busses can move along the 
highway. Unlicensed "gypsy" cabs have taken over most 
of the business in this area, in part by intimidating the 
licensed cab operators. A number of serious crimes had 
been attributed to the drivers of these illegal cabs and 
they have been the subjects of numerous complaints. 

The setting of the problem is shown on two maps in 
Figure 1. The left panel is a street map. It shows many 
features irrelevant to the problem and fails to show many 
features that are important. The right panel is a highly 
edited version of this map. It contains only the relevant 
features of the base map and adds the important omitted 
features, giving a much clearer picture of the setting. 

Figure 2 contains two maps summarizing conclusions 
from the analysis and important features of the response. 
The left map shows the primary travel routes of the gypsy 
cab drivers. The gypsy cabs make use of the street 
barricades and the parking lots to pick up customers. This 
map also shows that the bus stand and (legal) cab stand 
are too far from the people using the area. When the 
bars close after 3:00 AM there is great demand for 
transportation and the illegal cabs are in the best position 
to fill the demand. The response map on the right of 
Figure 2 shows how the highway barrier was moved to 
prevent gypsy cabs from getting to potential customers, 
the parking lots blocked off late at night to keep these 
cabs out, and how the legal cab stand and bus stand 
were moved to locations more convenient for the 
customers. This map is an important part of the process 
evaluation (Step 46). 

Together, these three maps nicely illustrate the nature of 
the problem and what was done about it. The result of 
this project was the virtual elimination of the gypsy cab 
problem in Tnsberg, without increasing disorder. 

Knutsson and Svik heavily annotated these maps to 
show features that a typical geographic information 
system would not show. This is good practice. Much 
information about problems is not contained 
in computers. 

Still, there are a number of features of good maps that 
are missing. There is no compass direction. However, 
direction plays no part in the problem so its absence does 
not detract from clarity of the maps. Also missing is a 
scale showing the relative size of map features. This 
impedes understanding of those who are unfamiliar with 
the area. 

Read More: 

Boba, Rachel (2005) Crime Analysis and Crime Mapping: 
An Introduction. Thousand Oaks, CA: Sage Publications. 

Harries, Keith (1999). Mapping Crime: Principle and 
Practice. Washington, DC: National Institute of Justice, 
Crime Mapping Research Center. 

Knutsson, Johannes and Knut-Erik Svik (2004) Gypsy 
Cabs in Tnsberg. Submission to the Herman Goldstein 
Awards. (accessible at www.popcenter.org) 

Jerry Ratcliffe has a list of mapping tips at: 

www.jratcliffe.net 


Creating Useful Maps 

1. Know what information your audience will find useful (and what information is confusing). 

2. Keep maps simple. Eliminate all features that do not contribute to understanding the problem. 

3. Avoid graphics that draw more attention to themselves than the data. 

4. Include details that help the viewer understand the problem, even if that means adding this information by hand. 

5. Include a scale and, if needed, a compass orientation (usually North is to the top). 

6. Use meaningful gradations to show intensity of hot spots. For example show colors becoming increasingly hot 
(yellow to red) as the problem worsens. 

7. Apply the correct dimension of crime concentration: dots for places (and sometimes victims); lines for 
concentrations along streets and highways; and areas for neighborhoods. 

8. Make use of tables and figures along with maps. 

Figure 1: Locating The Problem And Showing Its Setting 

Figure 2: Analyzing The Problem and Showing Response 


56. Use simple tables

Tables are effective tools for telling a compelling story 
if they are made simple. But the software used to 
create tables adds unnecessary and distracting 
packaging - the lines and labels used to interpret the data 
- and analysts do not always organize tables in a way that 
makes intuitive sense. 

Assume that you are trying to show that the way beer is 
displayed facilitates beer thefts from stores. Some stores 
display the beer near the front entrance and some at the 
rear. You are trying to show that rear display stores have 
fewer incidents of beer thefts than those where the 
display is in the front. Table 1 gets in the way of this 
message. The data are poorly organized and the 
packaging is distracting. 

Table 2 properly organizes the data. The percentages are 
made central to the story. Because the raw numbers do 
not tell the main story, but may be useful to a reader who 
wants to look more closely, they are made subservient by 
enclosing them in brackets. Finally, instead of row 
percentages (as in the first table), Table 2 uses 
column percentages. 

Whenever we examine a relationship in which something 
may be causing something else, it is best to put the cause 
in the columns and use column percentages. Then, make 
comparisons across the rows. Here, we see immediately 
that 29 percent of the front-display stores had no thefts 
compared to almost 83 percent of the rear-display stores. 
At the opposite extreme, almost 46 percent of the front-
display stores had three or more thefts, but none of the 
rear-display stores did. 

Table 2 has less packaging. The bold borders have been 
removed and replaced by thin lines. Inside, the only 
remaining line separates the title from the content. 
Instead of lines, space is used to guide the reader's eye 
across rows and down columns. By informing the reader 
in the title that the important numbers are percentages 
(and the raw numbers are in brackets), there was no need 
to include a percent symbol in each cell. Only the column 
total remains. This tells the reader that the important sum 
is vertical. Finally, all percentages are rounded to one 
decimal place, thus allowing the column figures to line up, 
making interpretation easier. With all of these changes, 
most of the content of the table is data rather 
than packaging. 

A problem often has multiple causes. Though tables can 
be constructed to show large numbers of causes, a single 
table communicates poorly when you examine more than 
two causes. The basic principles of table construction 
remain the same: 

 All the causes go in the same direction 
(usually columns). 

 Summation goes in the direction of the cause 
(down columns). 

 Comparison of causes goes in the opposite direction 
(across rows, if causes are in columns). 

Table 3 is called a three-dimensional table because three 
things are examined (the earlier tables were two 
dimensional). Table 3 answers the question: is the 
relationship between display location and theft different 
for two different store chains (Drink-Lots and Tippers). The 
answer is that it is not. There is the same basic pattern for 
both chains that we saw in Table 2. In both cases, we sum 
the column and compare front-display stores to rear-
display stores. This implies that any store that displays 
beer at the rear will experience less theft, regardless of 
which chain it belongs to. 

In effect, Table 3 holds constant the type of store. Other 
factors can be held constant if we think they are 
important. For example, we could group stores by size 
(small, medium and large), and separately analyze the 
relationship between display location and theft for each 
size category. This would require three panels, but 
otherwise the same principles apply. 

Take note of several other features of Table 3: 

 If you add the raw numbers (in brackets) in the Drink-
Lots cells to their corresponding cells under Tippers, you 
get the raw numbers in Table 2. In other words, Table 2 
is a summary of Table 3. But you cannot derive Table 3 
from Table 2. 

 Because Table 3 contains two possible causes of the 
problem, we have added a vertical line to draw 
attention to the two types of stores. 

 The row labels apply to both store types, so there was 
no need to duplicate them. 

 Because of rounding in the percentages, they sometimes 
add to over 100. In some instances these sums can be 
just under 100, usually 99.9. Such small deviations are 
seldom of much concern. 

If you routinely produce the same tables for the same 
decision-makers, show them several different table 
formats with the same data. Determine which format 
helps them the most, and then use this standard format. 


Table 1: Location and Beer Theft (June) 
Table Column Headers: Location of Display Front, Location of Display Rear, Total
Table Row titles: Number of theft reports, 0, 1-2, 3 or more, Total

0, 7 (17.5%), 33 (82.5), 40
1-2, 6 (46.15%), 7 (53.85%), 13
3 or more, 11 (100%), 0 (0%), 11
Total, 24 (37.5%), 40 (62.5%), 64

Table 2: Percent of Stores with Reported Beer Thefts 
(Numbers in Brackets) 
Table Column Headers: Location of Display Front, Location of Display Rear
Table Row titles: Thefts in June, 0, 1-2, 3 or more, Total

0, 29.2 (7), 82.5 (33)
1-2, 25.0 (6), 29.2 (7)
3 or more, 45.8 (11), 0.0 (0)
Total, 100.0 (24), 100.1 (40)

Table 3: Percent of Stores with Reported Beer Thefts by Retail Chain 

Drink-Lots Stores
Column Headers: Front Display, Rear Display
Row Titles: Thefts in June, 0, 1-2, 3 or more, Total

0, 30.8 (4), 84.2 (16)
1-2, 23.1 (3), 15.8 (3)
3 or more, 46.2 (6), 0.0 (0)
Total, 100.1 (13), 100.0 (19)

Tippers Stores
Column Headers: Front Display, Rear Display
Row Titles: Thefts in June, 0, 1-2, 3 or more, Total

0, 27.3 (3), 81.0 (17)
1-2, 27.3 (3), 19.0 (4)
3 or more, 45.5 (5), 0.0 (0)
Total, 100.1 (11), 100.0 (21)


57. Use simple figures

Like tables and maps, figures and charts are effective 
tools for conveying information, but only if they are 
kept simple. All figures consist of two parts packaging 
and content. Content is the information you 
are interested in conveying to others. The purpose of the 
packaging is to ensure that the content can be quickly, 
easily, and accurately interpreted. Simplicity means 
keeping the packaging to a minimum. The most common 
mistake is adding elements that get in the way of the 
story. To illustrate this, we begin with an example of a 
poorly designed figure. Then we will show how figures 
become clearer and more powerful by making 
them simpler. 

Figure 1 is a pie chart that is supposed to show how 
burglars entered homes. The 3-D image distorts the 
message. As we will see later, doors are the biggest 
problem, and the rear window ranks fourth, behind 
"other," as the entry of choice for these burglars. The 3-D 
effect inflates the importance of the slices in the front (in 
this example, front windows, the least likely point of entry) 
while deflating the importance of the slices in the back. 
The single valuable feature of a pie chart is that it shows 
how the parts contribute to the whole. This is lost when a 
3-D effect is used. Note that a variety of shades and 
patterns need to be used to display the six categories. This 
adds clutter. 

Image of Figure 1: Methods of Entry pie chart

Figure 2 shows the distortion that 3-D effects can produce 
in bar charts. Comparing bar heights is difficult because 
one has to choose between the front top edge and the 
back top edge of the bar. 3-D effects should never 
be used. 

This chart has a number of other features that make it 
hard to use: surface shading that masks contrasts 
between the bars and background, redundant bar labels 
and vertical axis labels, and distracting horizontal lines. 
The frame around the figure is superfluous. 

Image of Figure 2: Methods of Entry bar graph

The simple bar chart in Figure 3 communicates 
information very effectively because all the confusing 
features of Figure 2 have been removed. If we wanted 
each bar to show the exact percentage, we could label 
the tops of the bars. But then we should remove the 
vertical axis, as this feature communicates the 
same information. 

Additionally, the data in Figure 3 have been reorganized. 
Instead of raw numbers of burglaries, the chart shows the 
percentage of the total. This communicates two points: 
which methods are more frequent, and what part of the 
whole each method represents. If you need to show the 
relative contribution to a whole, use percentages in a bar 
chart rather than a pie chart. 

Another feature of Figure 3 is that the categories are 
arranged in a meaningful order: from most to least. This 
points to where your readers should focus their attention. 
Meaningful order is hard to communicate in a pie chart 
because it has no obvious beginning or end. There really is 
no need to use a pie chart because bar charts can 
communicate better. When you have data in categories, 
bar charts are simple and effective. 
 

Do not forget the figure title. In Figure 3 the title boldly 
tells a story. Not only is this far more interesting than 
"Methods of Entry," it makes the story unambiguous. In 
short, Figure 3 can stand by itself. Without reading any 
accompanying text, the reader gets the point. 

Image of Figure 3: Doors are the Problem bar graph 

The final figure depicts a line graph. These are typically 
used when tracking data over time. In Figure 4, the data 
cover 6 months. The dots symbolize the burglary count, 
and the lines indicate a continuous connection over time. 
You should label the vertical axis so the figure 
communicates the story on its own. In this figure, we 
know at a glance that the vertical axis shows the number 
of burglaries, rather than the burglary rate. 

Image of Figure 4: Burglary is Declining line graph

If you prefer to show the number of events at each time 
period, label the dots, but remove the vertical axis: it's 
now redundant. Be careful, however. Numerical labels at 
every time point can make a chart difficult to read. If 
multiple graphs are shown in the same figure (for 
example, the trend in burglaries for several police 
districts), make sure the different lines are clearly marked 
and easily differentiated over the chart. 

Read More: 

Kosslyn, Stephen (1994). Elements of Graph Design. New 
York: W. H. Freeman. 

Designing Effective Figures 

 Keep them simple. Don't over-package. 
 Do not use superficial effects, like 3-D. 
 Avoid pie charts. 
 Use bar charts for data that comes in categories. 
 Use line graphs for trends over time. 
 Use labels effectively. 
 Choose titles carefully. 
 Make them stand on their own, without help from the text. 


58. Organize powerful presentations

Apresentation should begin with a basic question, 
use a framework to move through a description of 
findings, and end with a set of specific conclusions 
(see Step 54). Graphical material should be prepared 
following the guidance in Steps 55 through 57. In this 
step we will focus on the story you are telling. In Step 
59, we will look at how the presentation should be 
delivered, including the use of PowerPoint. 

The main focus of your presentation should be to answer 
specific questions that will aid decision-making, and it 
should consist of the following: 

 A set of slides organized around your story. 

 A graphical motif or outline slide to keep your audience 
focused on the story. 

The slides illustrates a presentation of analysis findings. 
The presenter, Sergeant Smith, has two goals. The first is 
to answer the question, "What causes this problem?" The 
second is to open up a discussion of possible responses. 
The title slide asks the question (and introduces the 
presenter). This and slides 2 to 4 constitute the 
introduction. Slide 2 reinforces a set of already agreed 
points that serve as a foundation for what follows. Slide 3 
outlines the presentation and slide 4 summarizes 
data collection. 

The framework is presented in the fifth slide. Sgt. Smith 
uses the crime triangle. He keys all of the findings that 
follow to this triangle. (Note that this only works if 
Smith's audience is already familiar with the triangle. If 
they are not, then Smith should use a different 
framework.) To reinforce this message, and to keep the 
audience from getting lost, Sgt. Smith uses the triangle 
motif throughout the presentation of findings, with slight 
but important modifications: the shaded side and the 
color change as slides move from targets and guardians, 
to places and managers, and to offenders and handlers. 
The circular arrow in slide 5 indicates the 
counterclockwise order in which Sgt. Smith will present 
the findings. So in this slide, Sgt. Smith has simultaneously 
described his framework and provided an outline of the 
main findings. 

Slides 6 to 13 present tables, figures and maps that tell 
the audience about the elements described in the 
framework. A bar chart might show the actions used to 
protect targets. A location map might show the places 
where the problem is particularly prevalent in contrast to 
where it is absent. Photos might show particularly 
important features of these sites. A table might show the 
frequency with which offenders are arrested. 

Slide 14 summarizes these findings. Here, the triangle 
shows all sides shaded, reinforcing the point that the 
separate findings are part of a larger whole. The final 
slides list response options that are consistent with the 
findings and options that are inconsistent. Though Sgt. 
Smith gives his expert opinion, these final slides are 
meant to open up a discussion that is informed by the 
earlier findings. It is the decision-makers who have the 
final say in this matter. 

It is important to keep your audience focused on the 
larger story and from getting lost in the details. Two 
methods for accomplishing this are to use an ongoing 
motif (like the triangle in the figure) or a highlighted 
outline slide. When using an outline slide, the outline is 
shown before each topic. The topic to be presented is 
highlighted on the outline and the other topics are 
dimmed. In Sgt. Smith's presentation, the outline slide 
would be shown four times, before each of the 
main topics. 

Handouts of your slides are useful, but there are some 
limitations. You can make last-minute changes in the 
slides more easily than in the handouts. If you expect 
major last-minute changes, handouts may not correspond 
to the images. Color slides are often not legible when 
photocopied in black and white. If you are using 
PowerPoint, then the "pure black and white" option in 
the "Print" menu will temporarily convert your color slides 
to black and white for printing. 

Most decision-makers are not as interested as you are in 
the methods you used to analyze your problem. Therefore, 
do not spend a great deal of time describing your 
methods, unless this is the objective of the presentation. 
Rather, summarize the main elements (see slide 4). You 
can prepare separate slides about methods, held in 
reserve, should audience members have questions about 
your methods. 

Read More: 

RAND, Guidelines for Preparing Briefings, Santa Monica, 
CA, 1996, 

www.rand.org/publications/CP/CP269/CP269.pdf 

Ratcliffe, Jerry H, (2004) "Jerry's Top Ten Crime Mapping 
Tips." 

http://www.jratcliffe.net/papers/Jerry%27s%20top%20ten 
%20mapping%20tips.pdf 


Images of presentation slides

Slide 1: 
What Causes the XYZ Problem ? 
Sgt. Rodney Smith 
Problem Analysis Section 

Slide 2: 
What is the XYZ Problem ?
 High number of reported X events. 
 Concentrated in sector Y. 
 First documented in 1986. 
 Does not respond well to enforcement. 
 Common to other police forces. 

Slide 3: 
This Presentation Shows 
 Data sources used 
 How the data was organized 
 Why we have this problem 
 Possible responses 

Slide 4:
Analysis of XYZ Problem 
 Undertaken by Problem Analysis Section 
 Data from a Variety of Sources 
-Reported X events 
-Interviews with Merchants & Shoppers 
-Offender Interviews 
-Review of CCTV recordings 
 Experts from other Police Forces 

Slide 5: 
Elements of the XYZ Problem 
Image of crime triangle

Slides 6-13: 
Slides describing targets and guardians 
Slides describing places and managers 
Slides describing offenders and handlers 

Slide 14:
Causes of the XYZ Problem 
A bulleted summary of the previous slides

Slide 15:
Inconsistent Responses
Targets and Handlers 
a. 
b. 
Places and Managers 
a. 
b. 
Offenders and Handlers 
a. 
b. 

Slide 16: 
Consistent Responses
Targets and Handlers 
a. 
b. 
Places and Managers 
a. 
b. 
Offenders and Handlers 
a. 
b. 
 

59. Become an effective presenter

All professionals are required to make presentations, 
and presentation skills are becoming as important 
as good writing. The key to a good presentation is 
thorough preparation. The following points come from a 
variety of sources, including our own experiences - 
good and bad. 

Preparation 

Never try to "wing it." Even experienced presenters are 
often nervous, so do not be concerned about pre-
presentation jitters. Thorough preparation helps keep 
nerves under control. 

1. Know your topic. 

2. Know your audience, including who else is
presenting.

3. Establish presentation length. 

4. Prepare to finish a few minutes early, but take full 
time if you need it.

5. Rehearse presentation and time it. 

6. Rehearse again, if necessary. 

Check out the room on the presentation day 

Making sure you understand your presentation 
environment accomplishes three objectives. First, it keeps 
you from being surprised. Second, it allows you to make 
contingency plans. Third, it helps you remain calm. This is 
particularly true when you are presenting at a conference 
or some other venue outside your agency. Hotel 
conference facilities vary considerably in their layout. 

1. Is the equipment you need in place? 

 Flip charts 
 Black/white boards 
 Chalk/marker 
 Projectors 
 Microphone 
 Laser pointer 

2. Do you know how to use the equipment? 

3. Have you tried it out? 

4. Do you know how to summon the technician? 

5. Do you know how to dim lights? 

6. Are there parts of the room where the audience will 
have trouble seeing or hearing you? 

Projector 

Modern presentation equipment is both complex and 
failure-prone. Be sure you know how it works and have 
backup plans. If time permits, we always conduct a trial 
run with the equipment in the room. And during this trial 
run, we have found it useful to sit in different parts of the 
room and view the most complex slides. Even if you 
cannot make adjustments, you can forewarn your 
audience later. (For example, "Those of you on the left 
might want to move to the center as there are some 
graphics that are hard to see from the left-most seats.") 

1. Locate the projector in the best position for the
audience and yourself.

2. Make sure it does not block the view of the screen. 

3. If necessary, get help with presenting slides. 

4. Make sure slides can be read from the back of 
the room.

5. Draw curtains or blinds if necessary. 

6. Never assume things will work as planned! 

Presentation style 

Though knowing your material is critical, you need to 
have a style the audience appreciates. At minimum, make 
sure your audience does not have to work to overcome 
your style to understand your presentation. Treating your 
audience with respect is absolutely critical. 

1. Do not read your paper even if you have supplied 
written version.

2. Speak from notes (using cards prevents you from
losing your place)

3. Begin politely (thank chair, introduce yourself, greet
audience, etc.)

4. If possible, stand up and speak (this helps keep
control of the audience)

5. For lengthy presentations, you can vary where you
stand (but don't walk about restlessly)

6. Do not block the audience's view of the slide images. 

7. Make sure you can be heard. 

8. Don't speak too fast (about 120 words per minute 
is good)

9. Maintain eye contact with the audience (but not just 
one person!). 

10. Make sure your audience knows when it is 
appropriate to ask questions - during the presentation 
or after. 


11. Repeat questions so others can hear, answer 
concisely, and ask the questioner whether you have
addressed their question.

12. Make sure handouts are clear (and that you have
enough)

13. End on time. 

14. Try to enjoy yourself! 

Presentation Software 

PowerPoint and other similar presentation software allow 
the audience to receive the information simultaneously in 
two modes: visually and aurally. They are therefore more 
likely to understand and remember key points. There are 
four dangers from electronic presentations. First, they can 
result in standardized presentations that quickly become 
boring for more sophisticated audiences. Second, they 
can become so complex that the audience pays more 
attention to the media than the message. Three, 
breakdowns become more common with greater 
complexity. Four, they can stifle questions from the 
audience. Watching you fix a multimedia extravaganza 
bores your audience and wastes there time. Remember 
the KIS principle: Keep It Simple. 

1. Don't read your slides - your talk should not just be a 
repetition of the slides. 

2. Look at the audience - not at your slides! 

3. Begin with the title of the presentation, your name
and affiliation (but not your qualifications)

4. Use only one form of slide transition throughout, and 
only use a simple transition that does not distract the 
audience from your main points. 

Individual PowerPoint Slides 

Keep each slide simple, too. Lots of text on a slide is hard 
to read. Your objective is to make each slide telegraphic. 
Each slide should focus attention on a critical point and 
avoid distractions from that point. So make them easy to 
read and understand. 

1. Make only one point. 

2. Present just enough detail to address the point and
no more.

3. Avoid distracting sound effects, animation, type fonts, 
and transitions. 

4. Use dark background (e.g., deep blue) and light colors 
for text (e.g., yellow). 

5. Use large fonts and contrasting colors (not clashing,
e.g., blue and deep orange is clashing, but blue and
yellow is contrasting)

6. Avoid thin lines and letters that cannot be easily
distinguished from the background. This can be 
particular problem with line charts and maps.

7. Avoid too much red - you should use red selectively to 
emphasize important points. 

8. Use visual graphics rather than words when possible. 

9. Use clear and simple pictures, maps, figures,
and tables.

10. Use short bulleted phrases, not narratives, on 
word charts.

11. Ensure that each bullet is related to the main point
of the slide.

Finally, be safe 

Assume things will go wrong! If the projector fails, be 
ready with overhead projection slides and a projector. If 
that fails too, use your handouts as a substitute. If you 
are prepared for a breakdown, you will be less nervous 
and your audience will be sympathetic. 

1. Avoid technologies that break down frequently or
ones that you are not familiar with.

2. Have a backup plan for equipment and 
software failures.

3. Provide handouts of slides as supplements. 

Read More: 

Ratcliffe, Jerry H, (2004) "Jerry's Top Ten PowerPoint Tips." 

http://www.jratcliffe.net/papers/Jerry%27s%20top%20ten 
%20powerpoint%20tips.pdf 

Ratcliffe, Jerry H, (2004) "Jerry's Top Ten 
Presentation Tips." 

http://www.jratcliffe.net/papers/Jerry%27s%20top%20ten 
%20presentation%20tips.pdf 


60. Contribute to the store of knowledge

Much of what we know about problems today was 
unknown 20 years ago. This accumulation of 
knowledge is largely due to the sharing of 
knowledge by police practitioners and researchers in the 
United States, Canada, United Kingdom, and other 
countries. Steps 54 to 57 described how to communicate 
to decision-makers in your police force and in your 
community. You also have a duty to improve your 
profession by sharing your work outside your local agency 
and community. 

There are two approaches to communicating with your 
peers. The first is through written materials. These may be 
published in reports, professional periodicals, or popular 
press articles. The second is through presentations at 
professional conferences and meetings. The most effective 
strategy for communicating information is to use a 
combination of these approaches. 

Written reports can present a wealth of detailed, useful 
information that others can use as reference material. 
There are a number of ways of disseminating written 
information. It can be made available in a downloadable 
format from websites. It can be published in professional 
periodicals. Shorter pieces designed to capture people's 
attention can be published in professional newsletters and 
other periodicals. Finally, encouraging professional 
journalists to write about your efforts can reach even a 
wider audience. Shorter and more easily accessible pieces 
reach a wide audience, but contain less information. 

Conferences allow face-to-face communications, questions 
and answers, and discussions of the latest developments. 
Informal discussions are useful for exchanging viewpoints 
on ideas that have not developed enough to be 
published. And they allow you to seek advice from peer 
experts on difficult problems. 

The United States and the United Kingdom hold annual 
conferences on problem-oriented policing. There are also a 
host of crime analysis and other police conferences 
around the globe where you can present new information 
on problem solving. 

Finally, you should also consider conferences of other 
professions, particularly if you have been working with 
partners from other fields. The principal drawbacks to 
conferences are the limited time available to present 
material, the lack of detailed permanent records of 
conference proceedings, and the relatively small numbers 
of people who attend. But attendees can spread 
information to those not present. 

A comprehensive communications strategy should include 
the following: 

1. 
For people interested in the details, a technical report 
downloadable through an easily used website. 
2. 
For a large audience of general interest, one or more 
short articles in professional or popular periodicals, 
with references to the website. 
3. 
For professional colleagues and academics, a longer
article in a professional journal.
4. 
For a small but influential group of professional
colleagues, at least one presentation at 
professional conference.

Additionally, it is helpful to send copies of articles to 
people who are interested in the topic you are 
investigating. This not only communicates your ideas, but 
also allows you to solicit advice as to how to 
communicate your ideas to others. 

Professionals are particularly interested in the following: 

1. Discoveries of new or changing problems. 

2. Advances in analytical techniques that can answer
new questions, or answer old questions more
precisely and with less error.

3. New responses to problems or new applications of 
old responses.

4. Evidence about the effectiveness, lack of effectiveness, 
or side-effects of responses. 

Each of these topics can be written as a case study of 
your particular problem. The basic outline for a useful case 
study covers four points: 

1. Dissatisfaction with the old situation - why the
standard understanding or practice is insufficient in
particular circumstances.

2. Search for alternatives - how a new understanding or 
practice was discovered. 

3. Evidence supporting alternatives - comparison of old 
and new approaches. 

4. Conclusions and implications - summary of what
people should consider, given this new information.


This outline follows the SARA process. Scanning reveals 
dissatisfaction with a particular circumstance. Analysis is a 
search for a new understanding of the problem. Response 
requires a systematic comparison of alternative 
approaches and the selection of a particular new 
approach. And assessment summarizes what one has 
learned from the experience. 

The table shows how this outline can be applied to each 
of the four case study topics. These types of case studies 
can be combined, as circumstances require. A new 
technique for problem analysis might reveal a new type of 
problem, for example. In such a circumstance, the first two 
types of case study can be combined. 

Similarly, a description of a new response to a problem 
might include evaluation information, thus combining the 
last two types of case study. Other combinations 
are possible. 

Finally, we offer a plea on behalf of crime analysis as a 
profession and crime science as a discipline. However 
much you want to make yourself clearly understood, never 
give in to the temptation to exaggerate your evidence. 

Nothing is more likely to damage your reputation, and 
that of your colleagues, than being seen to stretch the 
facts. Other people may cut corners or leap to 
conclusions. Crime analysts lend diligence and integrity to 
what is sometimes a haphazard process. If you don't 
know the answer or only partly understand the problem, 
say so. That way, when you do know the answer, people 
will be more willing to trust your professional judgment. 

The 21st century is becoming the century of analysis in 
policing, and you can make a large contribution. A 
hundred years from now, analysis will be firmly 
established in policing, and much will have changed. The 
technology will certainly be different. But more 
importantly, our successors will know a great deal more 
about crime and its prevention than we do. And they will 
know this because you and people like you asked 
important questions, collected and analyzed data, and 
reported your results with honesty and clarity. 

Table: Four Types of Case Studies 
Column headers: Outline, 1. New Problem, 2. New Analytical Technique, 3. New Response, 4. New Evidence of Effectiveness
Row Titles: I. Dissatisfaction, II. Search, III. Evidence, IV. Conclusions 

I. Dissatisfaction
1. Discovery of an anomalous situation 
2. Why old technique is limited
3. Why old response is limited 
4. Uncertainty of effectiveness of response under particular circumstances 

II, Search
1. Exploration of what is different 
2. How the new technique was discovered 
3. How the new response was discovered
4. Difficulties in evaluating response in these circumstances 

III. Evidence
1. Comparison of old problem to new problem 
2. Systematic comparison of old technique to new based on objective criteria 
3. Systematic comparison of old response to new based on objective criteria 
4. Evaluation methods used and their results

IV.  Conclusions
1. What this implies for problem solving 
2. Circumstances where new technique is particularly helpful
3. Circumstances where new response is particularly helpful
4. Circumstances where response should be used and expected results


GLOSSARY AND INDEX

Term; 3-D Mapping 
Definition: High-definition mapping that 
portrays locations within buildings 
Step:  24 

Term: 80-20 rule 
Definition: The principle that a few people or 
places are involved in a large proportion of events 
Step: 18, 20, 22, 30, 31, 54 

Term: Acute hot spots 
Definition: Hot spots that suddenly appear, i.e., have not been present for a 
long time, not chronic (See Chronic hotspots and Chronic problems) 
Step: 23 

Term: Acute temporal clustering 
Definition: A very high concentration of crime 
in a small part of 24-hour cycles 
Step: 25 

Term: Acute troubles 
Definition: Transient sets of recurring events that might go away without 
engaging in problem solving activities, but could also evolve 
into chronic problems 
Step: 14 

Term: Adaptation 
Definition: Long-term changes in offender population behaviors in response 
to crime prevention 
Step: 11, 46 

Term: Analysis 
Definition: The second stage in the SARA process, involving systematic 
examination of the problem to identify possible causes that might 
be susceptible to responses 
Step: 4, 5, 6, 7, 8, 14, 15, 16, 18, 20, 23, 32, 33, 35, 36, 38, 44, 46, 52, 
54, 55, 58, 60 

Term: Anticipatory benefits 
Definition: Benefits from crime prevention that begin prior to initiation of 
crime prevention treatment 
Step: 11, 46, 52 

Term: Anticipatory benefits, pseudo 
Definition: The appearance of anticipatory benefits caused by smoothing data 
(i.e., the use of a moving average) 
Step: 52 

Term: Aoristic analysis 
Definition: A statistical method for determining the 24-hour rhythm of 
crimes when the exact time of crime commission is unknown 
Step: 25 


Term: Assessment 
Definition: The fourth stage in the SARA process, involving evaluating the 
effectiveness of the response
Step: 1, 4, 7, 24, 37, 38, 46, 54, 55, 60  

Term: Attractors, Crime  
Definition: Areas of criminal opportunities  well known to offenders
Step: 17, 28  

Term: Behaviors
Definition: One of two criteria for classifying problems describing aspects of 
harm, intent, and offender-target relationships (see Environments)
Step: 15 

Term: Boost accounts 
Definition: An explanation for repeat victimization that suggests that the 
rewards to the offender for the first crime encourage the offender 
to repeat the offense against the same victim or to tell other 
offenders who then attack the same victim (see Flag accounts)
Step: 29

Term: Broad-spectrum treatments 
Definition: Crime prevention measures thatare effective against a wide variety 
of methods for committing a type of crime 
Step: 49  

Term: Broken windows policing 
Definition: A proposed policing strategy based on the principles that small 
offenses add up to destroy community life and that small 
offenses encourage larger ones, consequently police should pay 
particular attention to disorders
Step: 5 

Term: Buffer zone 
Definition: Area around a place or area. Often an area around a facility, hot 
spot, or treatment area
Step: 16, 51 

Term: Case-control study 
Definition: A systematic comparison oftroublesome persons, places, times, 
or events to untroublesome ones to find out the characteristics that 
might cause the problem. This type of study is particularly useful 
when troublesome cases are a very small proportion of all cases
Step: 17, 32, 33  



Term: Cases 
Definition: The people, places, and events you are studying - offenders, targets, 
victims, facilities, time periods (e.g., months or weeks), crimes, and so 
forth. In case-control studies, cases are the problem people, 
places, or events (see Case-control and Controls)
Step: 22, 32, 33, 37, 53

Term: CHEERS 
Definition: Acronym for elements of defining aproblem: Community, Harm, 
Expectation, Events, Recurring, and Similarity
Step: 14, 15, 54 

Term: Chronic hot spots 
Definition: Hot spots that persist for a long time (see Acute hotspots) 
Step: 23

Term: Chronic problems 
Definition: Long-term sets of recurring events that show no sign of abating and 
are largely resistant to traditional police work 
Step: 14

Term: Community policing 
Definition: Community policing focuses oncrime and social disorder through 
the delivery of police services that includes aspects of traditional law 
enforcement, as well as prevention, problem-solving, community engagement, 
and partnerships
Step: 1, 3, 4, 5 

Term: CompStat 
Definition: A police management system,pioneered in New York City, that 
uses up-to-date crime pattern information (often processed with 
a geographic information system) to hold geographic commanders 
(e.g., precinct and district) accountable for reducing crime 
Step: 3, 4, 5 

Term: Content 
Definition: The substantive information in atable or figure 
Step: 56, 57 



Term: Control group 
Definition: A group of people or an area that is similar to the treatment group or 
area, but does not receive treatment. Used in evaluations to 
control for the impact of other, non-treatment influences on crime 
Step: 47, 49, 51 

Term: Controls (for analysis) 
Definition: Statistical and evaluation design procedures to isolate the effect of 
one factor on some outcome from that of others. A group of people 
or areas not getting a response that are compared to those 
receiving the response to show what would have happened to the 
response group if the response group had not received the 
intervention (see Control group) 
Step: 47, 48, 49, 51 

Term: Controls (in case-control studies) 
Definition: In a case-control study, controls 
are those people, places, times, or 
events that do not have the 
outcome being studied, in contrast 
to cases which do have the 
outcome. For example, in a case-
control study of high-assault bars, 
the cases are bars with many 
assaults and the controls are bars 
with few or no assaults (see Cases, 
and Case-control study) 
Step: 32, 33 

Term: Controls (on offenders) 
Definition: People and situations that reduce potential offenders' willingness or 
capabilities to commit crimes 
Step: 9, 15, 17, 39, 42, 43, 48 

Term: Correlation 
Definition: A measure of association between
two characteristics 
Step: 33 

Term: Costs 
Definition: Expenses or hardships associated 
with criminal events or 
prevention measures 
Step: 6, 12, 38, 40, 44,

Term: CPTED 
Definition: See Crime Prevention Through Environmental Design 



Term: CRAVED 
Definition: An acronym describing the  characteristics of items most likely 
to be stolen and standing for Concealable, Removable, Available, 
Valuable, Enjoyable, and Disposable
Step: 28, 31

Term: Crime Mapping/Maps
Definition: Examining how crime is spread geographically by showing where 
it is occurring on maps. See Geographic Information Systems 
Step: 1, 4, 5, 16, 17, 21, 23, 24, 29, 55, 58 

Term: Crime Prevention Through Environmental Design
Definition: A set of principles for designing and laying-out secure buildings 
and public spaces 
Step: 24 

Term: Crime triangle 
Definition: See Problem analysis triangle
Step: 8, 35, 54, 58

Term: Crime-neutral areas 
Definition: Areas attracting neither offenders nor targets, with adequate controls 
on behaviors
Step: 17  

Term: Cycles 
Definition: Regular fluctuations in crime that correspond to daily, weekly, 
monthly, annual, or longer changes in human activity
Step: 22, 25, 26, 47, 50 

Term: Defiance 
Definition: Offenders challenge the legitimacy of prevention efforts and commit 
more offenses rather than fewer
Step: 11  

Term: Den (of iniquity) problems 
Definition: Problem characterized by substantial involvement of repeat 
places (see Problem analysis triangle, place). Occurs when new 
potential offenders and new potential targets encounter each 
other in a place where management is weak
Step: 8, 15

Term: Diffused temporal clustering 
Definition: A relatively even, or random, spread of crime throughout 
24-hour cycles 
Step: 25 
  


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Term: Diffusion contamination 
Definition: Occurs when diffusion of benefits influences the control group or 
area during an evaluation. Leads to undervaluing the treatment (see 
Displacement contamination) 
Step: 51

Term: Diffusion of benefits 
Definition: Reducing crime beyond the focus  of the prevention scheme; a 
multiplier of effectiveness 
Step: 11, 13, 38, 47, 49, 51

Term: Diffusion of benefits, crime type 
Definition: Additional crime types blocked 
Step: 13 

Term: Diffusion of benefits, geographical 
Definition: Additional prevention over space 
Step: 13 

Term: Diffusion of benefits, tactical 
Definition: Additional methods thwarted 
Step: 13 

Term: Diffusion of benefits, target 
Definition: Additional targets protected 
Step: 13 

Term: Diffusion of benefits, temporal 
Definition: Additional prevention over time 
Step: 13 

Term: Diffusion-Displacement sites 
Definition: Areas used to detect diffusion of benefits and displacement that are 
separate from control group and treatment group 
Step: 51

Term: Displacement 
Definition: Offenders changing their behaviour to thwart preventive actions 
Step: 1, 4, 11, 12, 13, 38, 40, 46, 48, 49, 50, 51, 54 

Term: Displacement contamination 
Definition: Occurs when crime is displaced into the control group or area 
during an evaluation. Leads to inflation of effectiveness (see Diffusion contamination) 
Step: 48, 49

Term: Displacement countermeasures 
Definition: Prevention implemented to prevent expected displacement 
Step: 48 

Term: Displacement, crime type 
Definition: Offenders change type of crime 
Step: 12, 13, 49 

Term: Displacement, geographical 
Definition: Offenders move spatially 
Step: 12, 13, 46, 48 

Term: Displacement, tactical 
Definition: Offenders switch method for committing crime 
Step: 12, 13, 49 



Term: Displacement, target 
Definition: Offenders switch type of target or victim 
Step: 12, 13, 49

Term: Displacement, temporal 
Definition: Offenders switch time or day
Step: 12, 13, 48, 49

Term: Distribution 
Definition: A distribution shows how many cases, or what proportions of the 
cases, have each of the values for a variable 
Step: 22

Term: Duck (sitting) problems 
Definition: Problems characterized by substantial involvement of repeat 
victims (see Crime triangle). Occurs when victims continually interact 
with potential offenders at different places, but the victims do 
not increase their precautionary measures and their guardians are 
either absent or ineffective
Step: 8, 15

Term: Edges 
Definition: Boundaries between areas where people live, work, shop, or seek 
entertainment
Step: 16

Term: Enablers, crime 
Definition: Places with little regulation of behavior 
Step:  17 

Term: Environments 
Definition: A criterion for classifying problems describing where the problem 
takes place (see Behaviors) 
Step: 15, 28, 30

Term: Facilitators 
Definition: Physical items, social situations, or  chemical substances that help 
offenders commit crimes or acts of disorder
Step: 34

Term: Facilitators, chemical 
Definition: Substances that increase offenders' abilities to ignore risk, reward, 
or excuses
Step: 34  

Term: Facilitators, physical 
Definition: Things that augment offenders' capabilities, help overcome 
prevention measures, or incite deviancy
Step: 34 



Term: Facilitators, social 
Definition: Situations that provide support that stimulates crime or disorder 
by enhancing rewards from crime, legitimating excuses to offend, or 
by encouraging offending 
Step: 34

Term: Facilities 
Definition: Places that have special functions, like schools, businesses, 
and restaurants 
Step: 15, 18, 20, 23, 25, 27, 28, 30, 34, 38, 39, 42, 43, 44, 48 

Term: Facilities, risky 
Definition: Facilities that are frequent sites for crime and disorder 
Step: 18, 20, 23, 27, 28, 29, 34, 44 

Term: False Negative
Definition: An error in which the decision maker predicts something will not 
occur, but it does occur. Also known as a Type 1 error 
Step: 37, 53 

Term: False Positive 
Definition: An error in which the decision maker predicts something will 
occur, but it does not occur. Also known as a Type 2 error 
Step: 37, 53 

Term: Flag accounts 
Definition: An explanation for repeat victimization that suggests that 
some people are particularly vulnerable because of their 
occupation or their ownership of hot products (see Boost accounts) 
Step: 29 

Term: Focused temporal clustering 
Definition: Clustering of crime in distinct time ranges during 24-hour periods 
Step: 25 

Term: Framework, story 
Definition: A general "story shell" linking multiple interacting factors and 
that can be applied to a variety of problems 
Step: 54, 58 

Term: Generators, crime 
Definition: Areas to which large numbers of people are attracted for reasons 
unrelated to criminal motivation 
Step: 17 

Term: Geographic Information System 
Definition: See GIS 



Term: GIS 
Definition: Abbreviation for Geographic Information Systems. These are 
computer databases where all information is linked to geographic 
locations so that the data can be mapped. This allows comparisons 
of different areas and places for the same information, and 
examination of how two or more types of information vary together 
geographically. GIS is at the heart of all modern crime 
mapping processes 
Step: 2, 24, 29 

Term: Graded response 
Definition: The response increases in intensity or form as the number of repeat 
victimizations increases. An intervention used to reduce repeat victimization 
Step: 29 

Term: Handler 
Definition: Someone who knows the offender well and who is in a position to 
exert some control over his or her actions 
Step: 25, 28 

Term: Home Office 
Definition: The British equivalent of the U.S. Department of Justice, which has 
funded much research on crime prevention 
Step: 10, 19, 36, 38, 40, 41 

Term: Hot areas 
Definition: Types of hot spots showing neighborhoods where crime is concentrated 
Step: 23 

Term: Hot dots 
Definition: Types of hot spots showing locations with high crime levels 
Step: 23 

Term: Hot lines 
Definition: Types of hot spots showing street segments where crime is concentrated 
Step: 23 

Term: Hot products 
Definition: Things that are particularly attractive for theft 
Step: 18, 28, 29, 31 

Term: Hot spots
Definition: Geographic concentrations of crime 
Step: 3, 5, 16, 17, 18, 23, 48, 55 


 
Term: Hypothesis 
Definition: An answer to a question about a problem that can be true or false, 
and may or may not be supported by evidence 
Step: 20, 50 

Term: Impact evaluation 
Definition: A research study to determine if the response changed the problem 
Step: 46 

Term: Inner quartile range 
Definition: The upper and lower bounds of the 50% of the cases centered on the median 
Step: 22 

Term: Input 
Definition: Resources used in a response 
Step: 46 

Term: Intervention 
Definition: The response being applied to a problem (also called a treatment or 
response - see Response) 
Step: 4, 7, 11, 20, 35, 40, 44, 45, 46, 47, 48, 49, 50, 51, 52 

Term: Manager 
Definition: A person who has some responsibility for controlling 
behaviour in a specific location 
Step: 5, 8, 24, 28, 30, 33, 38, 40, 58 

Term: Mean 
Definition: A measure of central tendency, also known as the arithmetical 
average, calculated by summing the values for all the cases and 
dividing the sum by the number of cases. Useful for ratio data and 
symmetrical distributions 
Step: 22

Term: Median 
Definition: A measure of central tendency that divides the cases into two equal 
groups, half below the median value and half above 
Step: 22 

Term: Mode 
Definition: A measure of central tendency that shows the value that the largest 
number of cases possesses 
Step: 22 

Term: Moving average 
Definition: A method for reducing random fluctuation in a time series by 
recomputing the value for every data point based on the average of 
preceding time periods (see Smoothing) 
Step: 26, 52 

Term: Near repeats 
Definition: See Virtual repeats 
Step: 29 



Term: Nodes 
Definition: Destination places such as home, work, shopping, entertainment, 
and school (see Paths) 
Step: 16 

Term: Nominal Scale 
Definition: Values only name and cannot be ranked 
Step: 22 

Term: Odds Ratio 
Definition: A measure of association between two characteristics; useful when a 
case-control study is used 
Step: 33

Term: Offender 
Definition: A person who commits a crime or act of disorder 
Step: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 21, 22, 28, 
29, 30, 31, 34, 35, 36, 37, 39, 40, 41, 42, 43, 44, 46, 48, 49, 50, 52, 54, 58 

Term: Offenders, repeat 
Definition: People who commit many crimes or acts of disorder (see Wolf) 
Step: 3, 18, 30 

Term: Opportunity 
Definition: Short for "crime opportunity structure" and meaning the 
physical and social arrangements that make crime possible 
Step: 9, 12, 38, 44, 48, 50 

Term: Ordinal Scale 
Definition: A measurement scale in which values can be ranked but no other 
mathematical process can be applied to them 
Step: 22

Term: Outcome 
Definition: The impact of the response on the problem 
Step: 11, 33, 37, 46, 54 

Term: Packaging 
Definition: The lines and labels used in tables and figures (see Content). Small 
amounts are needed to help interpret content, but large 
amounts obscure content 
Step: 56, 57 

Term: Paths 
Definition: Routes connecting nodes 
Step: 16 

Term: Perceptions, offenders' 
Definition: How offenders view situations and prevention measures 
Step: 11, 34 



Term: Place 
Definition: A very small area, such as an address, street corner, or block face 
(see Crime triangle, den) 
Step: 8, 12, 13, 17, 18, 20, 27, 30, 32, 38, 39, 40, 48 

Term: POP 
Definition: See Problem-Oriented Policing 
Step: 4, 5, 6, 8, 14, 19, 46 

Term: POP Guides 
Definition: Summaries of research and practice dealing with specific 
problems and recommending particular responses. Available 
from www.popcenter.org and www.cops.usdoj.gov 
Step: 3, 19 

Term: Problem analysis triangle 
Definition: A graphic showing the six principal elements of routine activity theory 
- offenders, handlers, targets/victims, guardians, places, and managers - and used to 
organized the analysis of problems 
Step: 8, 16 

Term: Problem-Oriented Policing 
Definition: Policing that changes the conditions that give rise to 
recurring crime problems, and does not simply rely on responding to 
incidents as they occur or forestalling them through preventive patrols 
Step: 1, 3, 4, 5, 6, 7, 11, 15, 19, 21, 28, 38, 55, 60 

Term: Process evaluation 
Definition: Assessing how a response was implemented 
Step: 46, 47, 55 

Term: Provocations 
Definition: Physical designs or the way places are managed that 
provoke misconduct 
Step: 34, 38, 42, 54 

Term: p-value 
Definition: The probability that the difference between two sets of statistics is 
due to randomness (see Significance test) 
Step: 53

Term: Random fluctuations 
Definition: Short-term changes in problems caused by a large number of very 
small effects 
Step: 26, 53 

Term: Range 
Definition: A measure of dispersion showing the minimum and maximum value 
in a distribution 
Step: 22, 25



Term: Rates, crime
Definition: The ratio of crimes to targets for an area. Used to control for
differences in the number of targets (see Risk, crime)  
Step: 9, 17, 20, 24, 26, 27, 28, 32, 37, 42, 44, 49, 51 

Term: Ratio Scale 
Definition: A measurement scale in which there are equal intervals between 
the ranked values and a theoretically meaningful zero. Any 
mathematical procedure can be used on date measured on a ratio scale 
Step: 22 

Term: Regression to the mean 
Definition: The tendency for abnormal high or low levels of crime to move back 
to their normal levels 
Step: 47, 52  

Term: Response 
Definition: The third stage in the SARA process involving the development 
and implementation of an intervention designed to reduce a problem. Also a term for the 
preventive treatment or intervention being applied (see Intervention or Treatment)
Step: 2, 4, 5, 6, 7, 14, 15, 17, 19, 20, 21, 23, 26, 29, 35, 36, 37, 38, 39,
40, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 58, 60 

Term: Response group 
Definition: People or places receiving prevention, in contrast to 
control group
Step: 47  

Term: Results 
Definition: Activities accomplished in a response 
Step: 46  

Term: Risk, crime 
Definition: The chance a target will be involved in a crime
Step: 6, 16, 17, 18, 20, 21, 23, 26, 27, 28, 29, 31, 33, 34, 38, 39, 41 

Term: SARA 
Definition: An acronym for the problem solving process (see Scanning, 
Analysis, Response, and Assessment)
Step: 7, 21  

Term: Scanning 
Definition: The first stage in the SARA process, involving problem 
identification, verification, and classification 
Step: 1, 7, 14, 16, 18, 38, 54


 
Term: Scripts 
Definition: Standard actions carried out in a particular order by offenders to 
commit crimes 
Step: 35, 36 

Term: Significance level 
Definition: A threshold below which one rejects the possibility that the 
difference between two sets of statistics is due to randomness. 
Often, .05 (or 5%) is the rejection threshold (see Significance test) 
Step: 53

Term: Significance test 
Definition: A statistical procedure used to determine whether the difference 
between two groups of numbers is due to randomness 
Step: 53

Term: Situational Crime Prevention 
Definition: The science of reducing opportunities for crime 
Step: 1, 13, 16, 34, 38, 41, 54 

Term: Smoothing 
Definition: Removing random fluctuations from a time series by using a 
moving average (see Moving average) 
Step: 26, 52 

Term: Standard Deviation 
Definition: A common measure of spread useful for symmetrical distributions 
and ratio data. 
Step: 22, 53 

Term: Standard model 
Definition: Policing that relies primarily on the use of patrolling, rapid response, 
and follow-up investigations to prevent crime 
Step: 3 

Term: Target 
Definition: The person or thing an offender attacks, takes, or harms 
(see Victim) 
Step: 2, 8, 10, 12, 13, 14, 15, 16, 17, 20, 23, 25, 26, 27, 28, 29, 30, 31, 
34, 35, 38, 39, 41, 44, 47, 48, 49, 52, 54, 58 

Term: Targets at risk 
Definition: Persons or things vulnerable to being attacked, taken, or harmed 
Step: 26, 27 

Term: Temporal clustering 
Definition: Concentration of crime over 24 hours (See Acute, Diffused, and 
Focused temporal clustering) 
Step: 25 

Term: Time-window effect 
Definition: The underestimation of repeat victimization due to using a set 
time period 
Step: 29 



Term: Treatment 
Definition: See Response or Intervention 
Step: 48, 49, 51

Term: Treatment area 
Definition: Areas receiving the response in contrast to control areas 
(see Response group) 
Step: 48, 51 

Term: Treatment group 
Definition: See Response group 
Step: 49, 51 

Term: Trend 
Definition: A steady increase, decrease, or stable level of crime over some 
period of time
Step: 2, 20, 22, 26, 47, 49, 52, 57

Term: Uncontrolled case study 
Definition: A comparison of troublesome persons, places, times, or events 
without examining similar untroublesome ones. The results of 
such a study are often highly misleading.
Step: 32 

Term: Victim 
Definition: A human target or the owner of stolen goods or damaged property  
(see Target)
Step:  1, 2, 4, 6, 8, 10, 14, 15, 16, 18, 21, 22, 23, 25, 28, 29, 30, 31, 33,
34, 35, 36, 37, 38, 42, 44, 46, 47, 48, 54, 55 

Term: Victim, repeat 
Definition: A person or place with multiple crimes or acts of disorder (see 
Duck)
Step: 18, 23, 28, 29  

Term: Victimization, repeat 
Definition: The process leading to repeat victims 
Step: 8, 28, 29, 30, 33, 38, 46 

Term: Virtual repeats 
Definition: Victimization of targets that are very similar, though not identical 
(as in the case of repeat victims or places). Also called "near" repeats
Step: 29 

Term: Wolf (ravenous) problems 
Definition: Problems characterized by substantial involvement of repeat 
offenders (see Crime triangle). Occurs when offenders are able to 
locate temporarily vulnerable targets and places
Step:  8, 15 


FOR MORE INFORMATION: 

U.S. Department of Justice 
Office of Community Oriented Policing Services 

1100 Vermont Avenue, N.W. 
Washington, D.C. 20530 

To obtain details on COPS programs, call the 
COPS Office Response Center at 800.421.6770 

Visit COPS Online at the address listed below. 

www.cops.usdoj.gov 

e01052683 Created Date: August 8, 2005 
ISBN: 1-932582-52-5