Definitions and measurements
Source: data.gov.uk (2018-05-25)

Proven Re-offending statistics. Key statistics on proven reoffending in England and Wales. It gives proven reoffending figures for offenders who were released from custody, received a non-custodial conviction at court, or received a caution or reprimand.

Proven re-offending statistics: 
definitions and measurement 
 
Published  October 2011 

 
Contents 
Proven Re-offending Statistics Quarterly Bulletin  Background 
3 
Early Estimates of Proven Re-offending Statistics  Background 
10 
Local Measure of Re-offending  Background 
13 
Data Quality 
15 
Statistical modelling and coefficients 
26 
Appendix A: List of serious offences 
35 
Appendix B: Glossary of Terms 
41 
Appendix C: Comparison of the three measures of re-offending 
48 
Contact details and further information 
49 
 
 
 
 
 
 
 
 
 
 
      
 2

 
Proven Re-offending Statistics Quarterly Bulletin 
 
Background 
The Ministry of Justice launched a statistical consultation on improvements 
to the transparency and accessibility of our information in 2010 and a 
response to the consultation was published in March 2011. One aspect of 
the consultation was the measurement of proven re-offending. Responses 
have supported the proposals to move to a single framework for measuring 
re-offending where adult and youth data can be provided at the national and 
local level on a consistent basis. The response to the consultation is 
available here: 
  
www.justice.gov.uk/downloads/consultations/improvements-moj-statistics-
consultation-response.pdf  
 
Prior to this consultation there were six different measures of proven re-
offending:  
 national adult proven re-offending;  
 local adult proven re-offending;  
 national youth proven re-offending;  
 local youth proven re-offending;  
 Prolific and other Priority Offending (PPO); and  
 drug-misusing proven offending.  
 
The current framework for measuring proven re-offending integrates these 
approaches into a single framework. This allows users to:  
 form a clear picture of proven re-offending at national and local 
levels;  
 compare adult and youth results, and enable other work on transition 
between the youth and adult system;  
 understand how results for different offender groups (such as those 
managed by the prison and probation services, those under the PPO 
schemes, drug-misusing offenders, first time entrants, etc) fit in to the 
overall picture on proven re-offending; and  
 continue to be able to analyse proven re-offending behaviour of 
particular types of offender. 
 
 
 
 
 
 
 
 
 3

 
Measurement 
The underlying principle of measuring re-offending (or recidivism, which is 
the most commonly used term internationally) is that someone who has 
received some form of criminal justice sanction (such as a conviction or a 
caution) goes on to commit another offence within a set time period.  
 
Measuring true re-offending is difficult. Official records are taken from either 
the police or courts, but they will underestimate the true level of re-offending 
because only a proportion of crime is detected and sanctioned and not all 
crimes and sanctions are recorded on one central system. Other methods of 
measuring re-offending, such as self report studies, are likely to be 
unreliable. 
 
Following the Ministry of Justice consultation on Improvements to Ministry of 
Justice Statistics (2010), a proven re-offence is defined as any offence 
committed in a one year follow-up period and receiving a court conviction, 
caution, reprimand or warning in the one year follow up or a further six 
months waiting period. The data source is the extract of the Police National 
Computer (PNC) held by the Ministry of Justice. 
 
Definitions for the measurement of proven re-offending 
Cohort 
This is the group of individuals whose re-offending is measured. For the 
Proven Re-offending Statistics Quarterly Bulletin this is defined as all 
offenders in any one year who received a caution (for adults), a final 
warning or reprimand (for juveniles), a non-custodial conviction, or were 
discharged from custody.  
 
Offenders who were discharged from custody or secure accommodation 
(juveniles only) or commenced a Court Order are matched to the PNC 
database. A proportion of cases are lost in this process because they 
cannot be matched (see the section titled “Matching offender records” below 
for details). Additionally, offenders who appear multiple times in the cohort 
are only included once (see the section titled “Multiple Offender Entries” 
below for details).  
The group of offenders whose offending behaviour is proven is likely to be a 
sub-group of all active offenders. The Offending, Crime and Justice Survey 
(2003)1 estimated that around one in ten people in England and Wales aged 
between 10 and 65 had committed an offence in the previous twelve 
months, which translates into approximately 3.8 million people. This 
                                            
 4
1 The Offending, Crime and Justice Survey (2003) was a random probability 
survey of 10,079 people aged from ten to 65 and asked people about their 
offending history. Like any such survey its accuracy is dependent upon the 
level of honesty with which respondents completed the survey.  

 
compares to 632,000 offenders in the 2002 cohort used to measure re-
offending, underlining that the offenders whose proven re-offending 
behaviour is presented in the re-offending bulletin are a small and probably 
unrepresentative sample of the population of all active offenders. 
Index disposal (sentence type) 
The index disposal of the offender is the type of sentence the offender 
received for their index offence. For the Proven Re-offending Statistics 
Quarterly Bulletin this is defined as custody, court order, other disposal 
resulting from a conviction at court, such as a fine or discharge, caution 
(adult offenders), reprimand or final warning (young offenders).  
 
Index offence: Offences are only counted as an index offence if the offence 
is: 
 recordable (see below) 
 committed in England and Wales 
 prosecuted by the police 
 not a breach offence 
 
There are around 3,000 offence codes on the Police National Computer. 
These have been classified into 21 groups: violence (non serious), violence 
(serious), robbery, public order or riot, sexual, sexual (child), soliciting or 
prostitution, domestic burglary, other burglary, theft, handling, fraud and 
forgery, absconding or bail offences, taking and driving away and related 
offences, theft from vehicles, other motoring offences, drink driving 
offences, criminal or malicious damage, drugs import/export/ 
production/supply, drugs possession/small scale supply and other.   
 
Start Point (also known as the index date) 
This is the set point in time from when re-offences are measured. For the 
Proven Re-offending Statistics Quarterly Bulletin this is defined as the date 
of prison discharge, date of court conviction for non-custodial sentences, 
date of receipt for a caution, reprimand or final warning or the date of a 
positive drug test. 
 
Follow-up period 
This is the length of time proven re-offending is measured over. For the 
Proven Re-offending Statistics Quarterly Bulletin this is defined as twelve 
months from the start point. 
 
Waiting period 
This is the additional time beyond the follow up period to allow for offences 
committed towards the end of the follow up period to be proved by a court 
conviction, caution, reprimand or final warning.  For the Proven Re-
offending Statistics Quarterly Bulletin this is six months  
 
Figure 1 below illustrates why different offences are included or not in the 
re-offending measures for an example offender.  
 5

 
Figure 1: How events of re-offending are included in the measure 
 
Events A-E all occur in the one year follow up period, but Events F and G 
are outside this period, so would not be counted. Events A-D are all counted 
because they were all proven within the one year follow-up period or the 
further six months waiting period, but Event E, even though the offence took 
place in the one year follow up period, would not be counted, as the 
conviction did not occur within either the one year follow up period, or the 
further six month waiting period. The offender has therefore committed 7 
proven offences during the one-year follow up period (2 for Event A, 1 for 
Event B, 3 for Event C, and 1 for Event D). 
 
Sentence/disposal that an offence receives to count as a re-offence 
Offences that are proved by a court conviction, caution, reprimand or final 
warning count as re-offences.   
 
Offences that count as re-offences 
Offences are counted as re-offences if they meet all of the following criteria:  
 They are recordable. Not all offences are on the PNC and more 
recordable offences are enterered than non-recordable offences. 
Analysis comparing offences proven at court with offences recorded 
on the PNC suggests the most cost common offences that are not 
recorded relates to motor vehicles e.g. using a motor vehicle whilst 
uninsured against third party risks, speeding offences, keeping a 
vehicle on the highway without a driving license, or to television 
license evasion.  
 They were committed in England or Wales.  
 They are offences that were prosecuted by the police. PNC data is 
collected and input by the police and offences prosecuted by the 
police are likely to be recorded more comprehensively on the PNC 
than offences that are prosecuted by other organisations. For 
example, benefit fraud is prosecuted by the Department of Work and 
Pensions, and benefit fraud offences may be poorly represented on 
the PNC. 
 6

 
 Offences are only counted if they are proven through caution (for 
adults), reprimands or final warnings (for juveniles) and court 
convictions. Offences that are not proven, or which meet with other 
responses from the Criminal Justice System, are not counted. The 
Offending, Crime and Justice Survey (2003) estimated that 6 per cent 
of all offences resulted in any contact with the Criminal Justice 
System.  
 The offence is not a breach offence i.e breach of a court order, since 
we are only interested in new offences 
 
 
Adjusted baseline (predicted rate) 
Proven re-offending is related to the characteristics of offenders which 
means that any overall rate of proven re-offending will depend, in part, on 
the characteristics of offenders coming into the system (just as the 
examination pass rate of a school will be related to the characteristics of its 
pupils).  We use a modelling technique to produce a baseline figure 
adjusted to match the characteristics of the cohort we are comparing. For 
more details see the chapter on Statistical modelling and coefficients. 
 
Measures of proven re-offending  
Re-offending data are presented in the following ways: 
 The number of offenders; 
 The proportion of offenders who are proven re-offenders; 
 The average number of proven re-offences among re-offenders;  
 The average number of proven re-offences among all offenders 
including those who committed no proven re-offences (previously the 
frequency rate);  
 The proportion of proven offenders who committed a proven serious 
re-offence against the person. See page 31 for details of what counts 
as a serious offence. 
 The proportion of proven offenders who committed a proven serious 
acquisitive re-offence. See page xx for details of what counts as a 
serious acquisitive offence. 
The proportion of offenders who are proven to re-offend, adjusted to control 
for changes in offender characteristics. This measure is different from the 
other measures in that it does not come from actual re-offences, but from a 
statistical model created for the baseline year of 2008. This gives a better 
indication of actual change against a baseline. See the chapter on Statistical 
modelling and coefficients (page 23) 
 
Multiple Offender Entries (MOEs) 
Each offender is tracked over a fixed period of time and any proven offence 
committed in this period is counted as a proven re-offence. Offenders who, 
after entering the cohort in a given year, commits a re-offence and is either 
cautioned, discharged from prison or gets a non-custodial conviction in the 
same cohort year. This re-offence could also be included as a second entry 
for this offender into the cohort. 
 7

 
Figure 2: Example of an offender with Multiple Offender Entries 
 O
 
 
  
ffender 
Cautioned
Re-offence 1 
Offender starts a 
community 
sentence 
Re-offence 2 
Offender 
sentenced to 
3mnths in prison 
then released 
Re-offence 3 
1 year cohort period
Offender 
Cautioned
Offender 
Cautioned
Re-offence 1 
Offender starts a 
community 
sentence 
Re-offence 2 
Offender 
sentenced to 
3mnths in prison 
then released 
Offender 
sentenced to 
3mnths in prison 
then released 
Re-offence 3 
1 year cohort period
To date, publications have avoided the double counting of these multiple 
offender entries (MOE) by only counting an individual once based on their 
first proven offence in the relevant time period. In the illustration above the 
caution would be counted as the index disposal and the further two proven 
offences would be counted as re-offences. This avoids double counting of 
proven re-offences 
Proven re-offending measure 
In this publication the main tables (tables 1 to 17) in the report have been 
produced on the basis of the 'first proven offence in the relevant time period’ 
which led to an offender being included. This provides a picture of proven 
re-offending which is consistent with previous publications and tracks an 
offender, irrespective of the disposal they receive, to when they commit a 
proven re-offence 
The measure of proven re-offending now covers all offenders in any one 
year instead of the first quarter of a calendar year as in previous proven re-
offending publications. The result is many more offenders with multiple 
entries (MOEs).  
In addition, including cautions to identify a proven offence means many 
offenders’ first offence will be associated with a caution since cautions 
account for around a third of adult offenders in one year. Table 1 shows the 
number of offenders by their number of entries. 
Table 1: Number of adult offenders and their respective number of entries 
for 2000, 2002-2009 cohorts 
Multiple Offender 
Entries (MOEs)
2000
2002
2003
2004
2005
2006
2007
2008
2009
1
512,551
522,376
544,032
551,265
582,840
622,096
638,495
610,329
578,644
2x
75,311
77,813
81,651
78,969
81,120
87,589
91,695
88,207
83,785
3x
19,565
21,208
22,073
20,855
20,926
21,974
23,757
23,662
22,125
4x
6,195
6,689
7,074
6,835
6,725
6,807
7,652
7,917
7,360
5x
1,998
2,314
2,392
2,357
2,355
2,425
2,795
2,911
2,938
6 to 10x
1,240
1,510
1,689
1,641
1,505
1,513
1,966
2,341
2,308
greater than 10x
164
155
129
131
119
115
114
160
202
Total MOEs
104,473
109,689
115,008
110,788
112,750
120,423
127,979
125,198
118,718
% of total cohort
16.9%
17.4%
17.5%
16.7%
16.2%
16.2%
16.7%
17.0%
17.0%
Cohort
617,024
632,065
659,040
662,053
695,590
742,519
766,474
735,527
697,362 
The number of offenders with multiple entries has remained fairly constant 
over time. The proportion of the total that had multiple offender entries has 
remained at about 16 – 17 per cent between 2000 and 2009  
 8

 
 
Proven re-offending by index disposal, probation trust and prison 
In order to measure proven re-offending on a consistent and representative 
basis by offender management groups it is necessary to distinguish 
between the disposal types that led to an offender being included. Doing 
this allows the cohort to be defined according to the relative start point of an 
offender’s interaction with the prison (discharged from prison) or probation 
services (court order commencement). 
Tables 18 to 21 provide re-offending rates by disposal (sentence) types, 
These are produced on the basis of an individual’s first disposal (sentence) 
in that category. In the illustration above the individual would appear once in 
the caution category, once in the community order category and once in the 
custody category. These tables will include an overall prison and probation 
proven re-offending rate which will be the figures we quote publicly. 
However these figures should not be used when comparing proven re-
offending rates across different disposals to compare effectiveness. Instead 
the Compendium of Re-offending 
(www.justice.gov.uk/downloads/publications/statistics-and-data/ 
mojstats/compendium-of-reoffending-statistics-and-analysis.pdf) should be 
referred to as this analysis controls for offender characteristics in order to 
give a more reliable estimate of the relative effectiveness of different 
disposals 
Tables 22 to 24 provide re-offending rates by individual prison and probation 
trust. These are produced on the basis of an individual’s first disposal from 
each specified prison or probation trust. If the individual offender is 
discharged from two different prisons in the year they will appear in both of 
the prison’s re-offending rates. The same applies for offenders commencing 
court orders in more than one probation trust within the year. This is to allow 
prisons and probation services to track their caseload of offenders. 
 
 
 
 
 
 9

 
Early Estimates of Proven Re-offending Statistics 
 
Background 
Responses from the consultation and from earlier engagement with 
representatives of front-line offender management services supported the 
proposal to produce early estimates of proven re-offending using shorter 
follow-up and waiting periods. This is intended to provide offender 
managers feedback on the proven re-offending trends of offenders they are 
working with in time for them to adjust or build on offender management 
operational policy. This section of the new bulletin addresses these issues. 
 
Early estimates of proven re-offending are presented for four particular 
offender groups who are subject to specific offender management 
arrangements. These are offenders managed by the probation service, 
Prolific and other Priority Offenders (PPO) who are managed by a 
partnership of local front-line services, drug-misusing offenders who are 
managed by Drug Action Teams, and young offenders who are managed by 
Youth Offending Teams.  
 
Proven re-offending for the early estimates is measured in exactly the same 
way as for the headline proven re-offending measure except that the follow-
up period and waiting period are both three months each. (For the headline 
measure of proven re-offending they are twelve months and six months, 
respectively).   
 
The headline figures and early estimates differ in the following ways:   
 
 
Early estimates of proven re-offending rates are considerably lower 
than in the headline publication. This is because they cover a shorter 
time period.  
 
The shorter follow-up period and waiting period allow rates to be 
calculated for more recent groups of proven offenders. 
 
Early estimates of proven re-offending rates provide local offender 
management services with information on proven re-offending trends 
for the offenders they are working with. The headline re-offending 
publication presents the public with information on a wide range of 
proven re-offending trends and provides proven re-offending rates by a 
variety of breakdowns, such as age, gender, disposal etc. 
 
The shorter follow-up period and waiting period provides insufficient 
time for many serious re-offences to be committed and convicted. For 
this reason early estimates of proven re-offending rates do not include 
information on serious re-offending.  
 
10

 
 
Results in the headline measure are compared to a baseline rate, 
adjusted for changes in the offender profile. This relies on an estimate 
of the relationship between offender characteristics and proven re-
offending behaviour over twelve-months. An equivalent estimate has 
been carried out for the proven re-offending behaviour of offenders 
commencing court order over three months. This uses the same 
variables as the headline measure plus additional variables to ensure 
that the actual and predicted rates are identical for every probation 
trust in the baseline period (2008). The tables accompanying the early 
estimates present the adjusted baseline for each trust, and the text 
identifies those trusts where the actual rate is significantly higher or 
lower than the predicted rate in the most recent results available.  
Measurement 
Coverage: Results are provided for four types of offenders: probation 
offenders by probation trust, PPO offenders by upper-tier local authority, 
drug-misusing offenders by Drug Action Team, and young offenders by 
Youth Offending Team.  
Cohort: For probation offenders, the cohort is made up of all offenders who 
commenced a Court Order within a twelve month period. For PPO 
offenders, the cohort is made up of all offenders identified as a PPO who 
were discharged from custody, convicted at court, received a caution 
(adults), reprimand or final warning (juveniles) or tested positive for opiates 
or cocaine within a twelve month period. For drug-misusing offenders, the 
cohort is made up of all offenders identified as drug-misusing who were 
discharged from custody, convicted at court, received a caution or tested 
positive for opiates or cocaine within a twelve month period. For juveniles, 
the cohort is made up of all young offenders who were discharged from 
custody, convicted at court or received a reprimand or final warning within a 
twelve month period. 
Start Point:  Same as for the headline re-offending figures presented in the 
Re-offending Statistics Quarterly Bulletin.   
Follow-up period: Three months from the start point 
Waiting period: Three months  
Proven Re-offence: Same as for the headline proven re-offending figures 
presented in the Re-offending Statistics Quarterly Bulletin.   
Adjusted baseline: Proven re-offending is related to the characteristics of 
offenders which means that any overall rate of proven re-offending will 
depend, in part, on the characteristics of offenders coming into the system 
(just as the examination pass rate of a school will be related to the 
characteristics of its pupils).  We use a modelling technique to produce a 
baseline figure adjusted to match the characteristics of the cohort we are 
comparing. For more details see the chapter on Statistical modelling and 
coefficients (p 23). 
 
11

 
 
Multiple Offender Entries (MOEs): Same as for the offender management 
tables in the main bulletin. 
 
12

 
Local Measure of Re-offending 
 
Background 
Proven re-offending results from this measure have been published by the 
Ministry of Justice since February 2009 at the Government Office Region, 
Probation Trust and local authority level. This data is used to measure 
probation performance and the Ministry of Justice will continue to produce 
these measures while offender management systems still require them.  
The local proven re-offending data measures the re-offending of all 
offenders on the probation caseload. This includes offenders on licence and 
serving Court Orders. 
www.justice.gov.uk/publications/statistics-and-data/reoffending/local-adult-
reoffending.htm 
Local proven re-offending rates use the same follow-up period and waiting 
period to those for the early estimates. However, there are several large 
differences between the local measure and the early estimates. These 
include:   
 the sample of offenders. Local rates are estimated using all offenders 
on the probation caseload, including those on licence and those 
serving court orders. Offenders on the caseload are identified 
through four ‘snapshots’ of the caseload, taken each quarter. 
Offenders are included if they are on the caseload even if they have 
been on licence or serving the court order for longer than twelve 
months. The early estimates are based on offenders who commence 
a court order within a twelve month period.   
 Local rates define the period reported on by the period of re-
offending. The early estimates refer to the year of the index disposal.  
 
Measurement 
Cohort: All offenders on the probation caseload taken from four snapshots 
taken quarterly. 
Start Point:  The date of the snapshot. 
Follow-up period: Three months from the start point 
Waiting period: Three months  
Proven Re-offence: Same as for the headline proven re-offending figures 
presented in the Re-offending Statistics Quarterly Bulletin.   
 
13

 
Adjusted baseline (Predicted Rate): The predicted rate is the proportion of 
offenders we would expect to re-offend given the known characteristics of 
the offenders in the snapshot and re-offending rates in the baseline period. 
More detail on the predicted rate, and the statistical model used to calculate 
it, is provided in Appendix C of the Local Adult Re-offending bulletin.  
 
14

 
Data Quality 
The data required for measuring proven re-offending involve a range of data 
sources (NOMS prison database, probation data, identification of drug-
misusing offenders, identification of Prolific and other Priority Offenders, and 
young offenders in secure accommodation, and the criminal records from 
the Police National Computer) from a range of agencies (NOMS, probation 
trusts, the Youth Justice Board, Drug Action Teams, local authorities and 
the National Police Improvement Agency). These figures have been derived 
from administrative IT systems which, as with any large scale recording 
system, are subject to possible errors with data entry and processing.   
 
Police National Computer data 
Information regarding the proven re-offending behaviour of offenders has 
been compiled using the Ministry of Justice’s extract from the Police 
National Computer (PNC). The process involves matching offender details 
from the prison and probation services to the personal details recorded on 
the PNC. A proportion of cases cannot be matched and the figures 
presented in Table 1 are expressed as a percentage of the offenders that 
are matched. Like any large scale recording system the PNC is subject to 
errors with data entry and recording. The PNC is regularly updated so that 
further analysis at a later date will generate revised figures.  
 
The quality of the information recorded on the PNC is generally assumed to 
be relatively high as it is an operational system on which the police depend, 
but analysis can reveal errors that are typical when handling administrative 
datasets of this scale. The extent of error or omitted records on the PNC is 
difficult to estimate because it is a unique data-source. As a result, there is 
not always an obvious source of data to provide a baseline from which to 
assess data quality. For some types of results, however, comparisons can 
be made. For example, the trend in receptions into prison in each month is 
very similar using the PNC and prisons data (see below for details) although 
the number of receptions recorded on the PNC is consistently slightly lower 
because prisons data included cases on remand whereas the PNC does 
not. Another example is the number of cases that given a custodial, broken 
down by offence type, which is similar using the PNC and the Court 
Proceedings Database with a match rate of 97 per cent.   
 
 A number of improvements are routinely carried out: 
 Updates to the coding and classification of offences and court disposals, 
including the reduction of uncoded offences, the reduction in the use of 
miscellaneous offence codes and the clarification of the coding of breach 
offences; 
 
15

 
 Updates to the methods used to identify the primary offence, where 
several offences are dealt with on the same occasion, and the methods 
used to identify the primary disposal, where an offence attracts more 
than one court disposal; and,  
 Removal of some duplication of records within the database resulting in 
improvements to the efficiency and reliability of the matching process. 
Prison data 
Prison establishments record details for individual inmates on the prison IT 
system (either Prison-NOMIS or LIDS). The information recorded includes 
details such as date of birth, sex, religion, nationality, ethnic origin, custody 
type, offence, reception and discharge dates and, for sentenced prisoners, 
sentence length. The data from individual prison establishments then feeds 
through to a central computer database, called the Inmate Information 
System (IIS).  
 
In May 2009, the National Offender Management Service began the roll-out 
of a new case management system for prisons (Prison-NOMIS). During the 
phased roll-out, data collection issues emerged that affected the supply of 
data for statistical purposes from July 2009 to February 2010.  Specifically, 
statistical information on sentence length and offence group are not 
available on any of our prison datasets for this period 
 
In order to ensure the fullest possible set of data from July 2009 to February 
2010, sentence lengths were estimated for those prisoners received or 
discharged before the problems were resolved.  At the point when the 
problems were resolved, a small number of prison establishments were still 
using the old LIDS case management system; data for prisoners received or 
discharged from these prisons was assumed to be unaffected.  
For those prisoners received or discharged from prisons operating Prison-
NOMIS, efforts were made to populate their record with the correct 
sentence length using other data extracts. For example, many prisoners 
discharged in January 2010 were originally received into prison prior to July 
2009, so we were able to take their sentence length from unaffected 
datasets before the problems began.  Similarly, the majority of those 
received in early 2010 were still in prison in March 2010 when the problems 
were resolved, so we were able to use the sentence length in the corrected 
prison population data. 
Where it was not possible to populate a sentence length using other 
datasets, prisoners were allocated a sentence length band based on the 
number of days they spent in custody (taking account of early release 
schemes where relevant). 
 
16

 
Alternative estimation method 
As a check on the methodology, we created an alternative estimation 
process and compared the number of discharges in the second half of 2009 
in each sentence length band using the two methods.   
 
A number of estimation methods were considered, and each tested on the 
2008 data (prior to the data problems, hence we had a full year of data) to 
see which yielded estimates closest to the actual 2008 data.  This identified 
the following method: 
 
1. Calculate data for the first half of the year as a proportion of the full 
calendar year, for each year from 2001 to 2008; separately for each 
sentence length band or offence group (the 2 key breakdowns to be 
estimated). 
 
2. Apply the average of these proportions to the Jan-Jun 2009 data to 
estimate the 2009 annual totals; separately for each sentence length 
band/offence group. 
 
3. Scale the estimated numbers in each sentence length band or 
offence group to sum to the annual total recorded in the raw data 
(where the totals are known to be correct). 
 
Results 
The maximum difference between the two approaches was 2.6% in the 
band 12 months to less than 4 years; for all other bands the difference was 
less than 1%. 
 
Indeterminate sentence prisoners 
In addition to the above, data on the discharge of prisoners on 
indeterminate sentence (prisoners given a life sentence or indeterminate 
sentence for Public Protection (IPP) is provided from the Public Protection 
Unit Database (PPUD). This holds data jointly owned by the Offender 
Management and Public Protection Group (OMPPG) in NOMS and the 
Parole Board. 
 
PPUD records details of all indeterminate sentence prisoners at the point of 
conviction, those engaged in the Generic Parole Process and prisoners 
(determinate and indeterminate) who have been recalled from licence.  It 
also covers those who have received a restricted hospital order/direction 
from a Crown Court, and those remand and convicted prisoners who have 
been transferred from prison/detention centres to psychiatric hospital under 
the relevant sections of mental health legislation. 
 
All decisions taken by the NOMS casework sections and the Parole Board 
are recorded on the system. 
 
Personal information recorded includes (but is not limited to) name, date of 
birth, gender, identifying numbers, ethnicity, last known address, probation 
area and sentencing information.  
 
17

 
 
OMPPG and the Parole Board run monthly and ad hoc reports to cleanse 
data that are not otherwise identified by data validation routines built into the 
system. 
 
 
Probation data 
Since 2005, detailed information on the supervision of offenders (at the 
individual offender level) has been submitted by probation trusts on a 
monthly basis. These monthly ‘probation listings’ include information on 
offenders starting probation supervision. Between 2002 and 2005 this 
information was submitted quarterly, and prior to 2002 a different data 
collection system was in place, which meant that information on caseload 
had to be calculated based on the number of people starting supervision 
and the number of terminations. 
 
The quality of the information recorded on the probation data is generally 
assumed to be relatively high as it is a direct extract from an operational 
system upon which the probation service depends for managing offenders 
locally. The extract consists of a small number of key fields for which 
completion is mandatory. Probation Trusts have their own IT departments 
who manage their own data validation processes and when the data is 
received centrally it is subject to another set of data validation processes. 
Trends from the data are consistent with comparable time-series from the 
Courts Proceeding Database. Any large scale recording systems are 
subject to possible errors with data entry and processing but there are no 
known issues regarding the probation commencements data.   
  
 
Identification of drug-misusing offenders 
There are four ways a drug-misusing offender can be identified: 
 
 
Individuals who have tested positive for heroin or crack/cocaine 
following an arrest or charge for ‘trigger’ offences (largely acquisitive 
crime offences) as part of the Drug Interventions Programme (DIP) are 
included as adult proven offenders.  
 
  Any offender that received an OASys assessment whilst on licence or 
on a community sentence and are either recorded as being subject to a 
current Drug Treatment and Testing Order (DTTO) or Drug 
Rehabilitation Requirement (DRR), or are assessed as having a 
criminogenic drug need. 
 
  Any offender identified as requiring further drug interventions by 
Counselling, Assessment, Referral, Advice, Throughcare (CARAT) 
teams in prison, and now being released into the community. 
 
 
18

 
  Any offender identified by local Criminal Justice Integrated Teams 
(CJITs) as requiring further intervention for their drug use and offending 
as part of DIP. 
 
Drug Interventions Programme (DIP) 
The Drug Interventions Programme (DIP) was introduced in April 2003 with 
the aim of developing and integrating measures for directing adult drug-
misusing offenders into drug treatment and reducing offending behaviour. 
The programme comprises of a number of interrelated interventions:  
 
 Drug testing in police custody for specified Class A drugs – heroin, 
cocaine and crack cocaine – for individuals arrested for trigger 
offences (primarily offences related to acquisitive crime); 
 
 Assessment following a positive test to establish the extent of the 
individual’s drug-misuse, and whether the individual might benefit 
from further assessment, assistance or treatment; 
 
 Conditional cautioning which may include a DIP drug rehabilitative 
condition, tailored to the offender’s drug use and offending.   
 
 Restriction on bail for adults who have tested positive and whose 
offence is a drug offence or is drug-related.   
 
 Criminal Justice Integrated Teams (CJITs) manage offenders who 
have been referred to treatment and co-ordinate agencies and 
services so they offer access to joined-up treatment and support. 
They maintain strong links with both the National Probation Service 
and Prison Service to ensure the continuity of care whilst the offender 
is within the Criminal Justice System.   
 
Legislative changes have broadened the scope of the programme: 
 
 A major expansion of DIP took place in April 2006 to move the point 
of drug testing from the point of charge to the point of arrest and to 
introduce required (rather than voluntary) assessments. This change 
broadened the scope and size of the cohort coming into contact with 
DIP. 
 
 The latest changes took effect from April 2011, when the 
authorisation to conduct Drug Testing on Arrest was extended across 
England & Wales. Drug testing on arrest previously occurred only in 
‘intensive’ DIP areas, which had high levels of acquisitive crime. 
 
 
19

 
Data Sources 
Records of those who test positive are logged onto the Drugs Intervention 
Management Information System (DIMIS), which is managed by the Home 
Office. An extract of positive drug test records for the relevant period is used 
for a match to the PNC. 
 
Offenders identified as drug misusers via CARAT teams and CJITs are also 
recorded onto DIMIS, from which an extract is taken for the relevant period 
to match to the PNC. OASys records are collated centrally within the 
Ministry of Justice in the OASys Data, Evaluation and Analysis Team (O-
DEAT) database, from which an extract is taken for the relevant period to 
match to the PNC. 
 
 
Identification of Prolific and other Priority offenders 
The Prolific and other Priority Offenders Programme (PPO) aims to use a 
multi-agency approach to focus on a very small but hard core group of 
prolific/persistent offenders who commit disproportionate amounts of crime 
and cause disproportionate harm to their local communities. Full 
implementation of all three strands had commenced by the beginning of 
February 2005. In 2009, all local areas were asked to review their PPO 
schemes to ensure that the programme remained squarely focused on 
those offenders that were of most concern to the communities in which they 
live.    
 
The identification of a PPO is undertaken at a local level involving police, 
local authorities, prison and probation services and youth offending teams. 
The factors that influence the decision of whether an offender is included in 
the PPO programme are: 
 
 the nature and volume of crimes they commit; 
 the nature and volume of other harm they cause; and 
 the detrimental impact they have on their community. 
 
This process will typically involve police, prison and probation information 
systems and other tools available. 
 
The size of the PPO caseload at a local level is influenced by a range of 
factors, including the number of offenders who meet the locally agreed 
selection criteria and the capacity of local partner agencies to provide the 
intensive management of offenders under PPO supervision. 
 
 
20

 
PPO cohort data are derived from JTRACK, which is a management 
information and tracking tool used by practitioners in various criminal justice 
agencies to record details of the offenders being managed as PPOs in a 
local area. JTRACK relies on the accurate input of data by local users to 
ensure that the details of the caseload on the system reflect the caseload 
being managed. An extract of the caseload from JTRACK is taken for the 
relevant period to match to the PNC. 
 
 
Young offenders in secure accommodation 
Information about secure training centres (STCs) and secure children’s 
homes (SCHs) comes from the Youth Justice Board's (YJB) Secure 
Accommodation Clearing House System (SACHS) database. The under 18 
year olds in YOIs is also from SACHS, whereas information about young 
people aged 18 and held in YOIs is supplied by the Prison Service and 
private YOIs.  
 
The quality of the information recorded on the SACHS database is generally 
assumed to be relatively high as it is a direct extract from an operational 
system which is used to place young people in custody. The extract uses a 
number of key fields for which completion is mandatory when booking a 
young person into custody. 
 
Data processing and analysis 
The data underpinning the results are considered by Ministry of Justice to 
be broadly robust. Considerable work has been carried out ensuring data 
quality, and the data have been used for research publications. Scrutiny of 
the data source continues in order to ensure the data remains reliable.    
 
The National Audit Office (NAO) identified risk factors in its review of the 
reporting of PSA targets (NAO, 2005). The remainder of this section 
addresses these. 
 
Matching offender records 
This process involves matching prison discharges and court order 
commencements data with the Police National Computer database.  The 
process uses automated matching routines that look at offenders’ 
surnames, initials, and dates of birth, using direct name matching along with 
a variety of ‘sounds like’ algorithms.  The matching algorithm also searches 
through PNC held information on alias names and dates of birth for 
offenders. However, not all offenders are matched and a thorough analysis 
of bias in the matching system has yet to be undertaken.  Table 1 below 
shows that the overall matching rates between 2000 and 2009 have 
remained high. Additionally, matching rates are similar for both prison and 
court orders data. 
 
21

 
 
 
Table 1: Matching rates for the different data sources for 2000, 2002-
2009 cohorts  
2000
2002
2003
2004
2005
2006
2007
2008
2009
Prison
Prison discharges
87,083
87,338
85,920
86,970
84,897
83,725
87,340
95,824
94,114
Automatically matched to the PNC
80,572
81,211
80,121
81,125
79,398
78,285
81,874
90,021
88,745
Matched to an index date
73,810
75,121
73,327
73,390
71,246
68,185
69,741
76,668
74,189
Percentage matched to the PNC
92.5%
93.0%
93.3%
93.3%
93.5%
93.5%
93.7%
93.9%
94.3%
Percentage matched to the PNC and index 
offences (not breach etc)
84.8%
86.0%
85.3%
84.4%
83.9%
81.4%
79.9%
80.0%
78.8%
Court Orders
Court order starts
136,023
154,621
158,750
164,831
163,681
176,346
187,386
189,643
191,784
Automatically matched to the PNC
123,540
142,838
148,257
154,075
158,416
172,906
184,740
187,253
190,128
Matched to an index date
105,685
115,108
119,446
122,927
130,307
148,072
159,279
163,519
167,378
Percentage matched to the PNC
90.8%
92.4%
93.4%
93.5%
96.8%
98.0%
98.6%
98.7%
99.1%
Percentage matched to the PNC and index 
offences (not breach etc)
77.7%
74.4%
75.2%
74.6%
79.6%
84.0%
85.0%
86.2%
87.3%
YJB
YJB discharges
1,337
1,612
1,521
1,551
1,564
1,553
1,647
1,626
Automatically matched to the PNC
1,226
1,502
1,425
1,448
1,464
1,463
1,537
1,564
Matched to an index date
680
818
785
800
769
780
845
817
Percentage matched to the PNC
91.7%
93.2%
93.7%
93.4%
93.6%
94.2%
93.3%
96.2%
Percentage matched to the PNC and index date
50.9%
50.7%
51.6%
51.6%
49.2%
50.2%
51.3%
50.2% 
The total number of offenders matched to the PNC is substantially higher 
than the final figure for the cohorts – for example, in 2009 there were 
280,437 matched offenders but a final cohort size of 242,384. The main 
reasons for these discrepancies are: 
 Conviction dates for the beginning of the community, suspended or 
custodial sentence do not match the conviction date within seven days of 
the criminal records database (PNC); 
 The index offence was not dealt with by a Home Office police force – this 
ensures that only offences in England and Wales are counted; 
 Exclusion of all offenders where the index offence is a breach, since we 
are only interested in new offences; and, 
 Exclusion of Multiple Offender Entries (see above for a description). 
Counting rules 
The counting rules for choosing which prison discharges to include offer a 
variety of choices. For instance, it makes little sense to include offenders 
deported on release or who have died. These counting rules were 
enumerated and discussed to ensure a more accurate and consistent count 
and are reviewed on an annual basis to ensure a consistent approach. 
 
Complexity of data processing and analysis 
The data processing involved for measuring re-offending is complex. To 
analyse re-offending behaviour by previous offending or disposal history 
requires the extraction of criminal histories that can span a number of 
decades, and the subsequent matching of these histories against the 
probation caseload files and prison discharges in order to generate a 
dataset. 
 
22

 
The extraction of the criminal histories 
To quality assure the extraction of criminal histories, a small set of random 
samples of offenders was taken after the analysis to check, via a basic 
validation, that outputs of the SQL (Structured Query Language) program 
are accurate outcomes and the Ministry of Justice is confident that this 
process has been successful. 
 
Level of subjectivity 
There is relatively little subjectivity in the system. Occasional judgements 
are required (e.g. where to classify an offence) but these will not 
significantly influence the results. 
 
Maturity and stability of the data system 
The system is well established having been used a number of times to 
produce re-offending statistics for publication. Nonetheless, vigilance 
continues to be exercised to ensure the validity of the results.   
 
Expertise of those who operate the system 
Prison and court order data-feeds are continually monitored and 
improvement work is regularly undertaken to improve the reliability and the 
accuracy of datasets. The internal processing of the results within the 
Ministry of Justice has been subject to dip sampling of criminal histories and 
the statistical model has been extensively tested. 
 
Interpreting trends in the proportion of offenders who 
commit a serious re-offence against the person  
Care should be taken when interpreting the severity rate for the following 
reasons: 
 Time through the CJS – more serious offences are likely to take a 
longer time to progress through the Criminal Justice System than less 
serious offences. The proven re-offending statistics track proven re-
offending behaviour for a year upon offenders entering the cohort, plus 
an additional six months for convictions to be updated on the system. 
There is a risk that this time scale is not long enough to capture the most 
serious offences. However, analysis suggests that the number of serious 
proven re-offences picked up by the measure remains comparatively 
stable year on year, ensuring performance is comparable over time. 
 
23

 
 Reporting variation – variation in reporting time between police force 
areas and courts may also have an impact on how many serious 
offences are captured during the one-year follow up period. 
 
Data on historical trends 
The data used to measure re-offending is from the Police National 
Computer (PNC). Police forces started to enter criminal records locally in 
1995. In order to allow time for good practice among police forces in 
entering data onto the PNC to become embedded, PNC data was used to 
measure re-offending for the first time in 2000. In the headline bulletin, 
results are compared to 2000 to highlight long-term trends because it is the 
earliest data on re-offending that exists on a comparable basis. Results prior 
to 2000 cannot be compared to results from 2000 onwards for two main 
reasons:  
 Change in data source – re-offences are measured using data from 
the Police National Computer (which covers recordable offences), 
whereas data from years before 2000 was measured using the 
offenders index (which covered a narrower range of offences)  
 Change in measurement – the concept being measured from 2000 
onwards in these reports is that of using the offences date to 
measure re-offences (a period of time is allowed for offences to be 
committed, and a further period allowed for these offences to be 
proved by caution, reprimand, final warning or court conviction), 
whereas the concept being measured prior to 2000 was that of using 
the conviction date to measure re-convictions (any conviction 
occurring in a set period of time, whether or not the offence occurred 
in that time period). 
 
However the compendium of re-offending statistics and analysis published 
in November 2010 provides the most consistent statistical series possible 
between 1971 and 2006, adjusting for known methodological changes. For 
more information please refer to Chapter 4.4 at the following link: 
 
www.justice.gov.uk/publications/statistics-and-data/reoffending/ 
compendium-of-reoffending-statistics-and-analysis.htm 
 
Results for 2001 cannot be calculated for offenders on Court Orders 
because of a problem with archived data on court orders. 
 
 
24

 
Local breakdowns of the headline re-offending rates are available from 2005 
onwards. Re-offending data is broken down by locality using the address 
and post-code information of the offender. Where this information is 
missing, the location of the processing police force is used instead. This is 
not a completely reliable indicator of the offender’s home address as 
offenders may offend in a different locality than where they reside. The 
completeness of this information has improved over time. In 2000, this 
information was omitted for 29 per cent of cases, which was considered too 
high to produce reliable results. By 2005, this was reduced to 16.5 per cent, 
and there has been a continuing downward trend since then.  
 
25

 
Statistical Modelling and Coefficients 
Introduction 
The characteristics of proven offenders are likely to be systematically 
different over time and by sentence type and as the Criminal Justice System 
targets particular sentences to offenders most likely to benefit from that 
type.  It is therefore important to note that it is not possible to reach firm 
conclusions about changes in rates over time, nor about the relative 
effectiveness of different sentence types, from actual proven re-offending 
rates. 
 
The Ministry of Justice has developed models to address these two issues: 
 modelling to adjust the baseline to reflect changes in offender 
characteristics (see below) 
 modelling to match offenders across sentence types to make valid 
comparisons (see The Compendium of Reoffending Statistics and 
Analysis 2011 www.justice.gov.uk/publications/statistics-and-
data/reoffending/compendium-of-reoffending-statistics-and-
analysis.htm ) 
 
 
Modelling to adjust for the varying composition of the cohort 
of offenders over time 
If the composition of the cohorts of offenders being compared differs 
significantly over time so that the type of offenders in one year is inherently 
more (or less) likely to re-offend, this may result in an apparent rise or fall in 
the re-offending rates even when there may be no ‘real’ difference for 
similar offenders over that time. In order to address this problem, we have 
adopted the following solution: 
 modelling the likelihood of proven re-offending based on known 
offender characteristics using historic data (which will be defined as 
the baseline)  
 identifying the characteristics of the most recent cohort  
 using the model, adjusting the baseline proven re-offending rate to 
match these characteristics 
 comparing this adjusted rate with the current rate to make a more 
realistic estimate of trends over time.   
In previous publications of proven re-offending statistics, this approach has 
been referred to as the predicted rate of proven re-offending.   
 
 
 
26

 
Statistical model 
The 2008 statistical model is an update and improvement on the 2000 and 
2005 logistic regression models and includes a range of offender 
characteristics available from the Police National Computer (PNC), such as 
age, gender, offence group and criminal history.   
   
The logistic regression model based on the 2008 data identifies a 
statistically significant set of variables that are related to proven re-offending 
and based on these provides a probability of proven re-offending for each 
offender.  However, other factors, for which data on these samples are not 
available, such as drug and alcohol use, employment, accommodation and 
marital background are likely to be significantly related to re-offending. 
 
This means that the adjusted proven re-offending rates are only valid for 
terms included in the final model.  Any adjusted proven re-offending rates 
for groups of offenders that have a common characteristic that is not in the 
final model (e.g. employment status or disposal type) can suffer from 
statistical biases and are, therefore, unreliable. 
 
For the 2008 model additional developments were included to ensure that 
the adjusted rate model was a more parsimonious model, more robust 
against changes in the number of offenders, and that interaction terms and 
non-linear terms were included where appropriate. The final decision for 
inclusion or exclusion of particular variables was heavily influenced by their 
statistical significance (typically p < 0.10). 
 
The Ministry of Justice believes that the method used for the construction of 
the statistical model for producing adjusted rates is robust and fit for 
purpose.  
 
 
Variables included 
The following notes provide some further detail on the 2008 model and 
show the relative impacts of different variables when holding all other 
variables constant.  
 
Gender 
Gender is included in the model as a categorical variable separating out 
males and females. Generally, males are more likely to commit a proven re-
offence than females.  
 
Age 
Age is included in the model for adults as a linear, quadratic and cubed term 
and is included for juveniles as a categorical variable separating offenders 
into seven age bands. Generally, younger adults are more likely to commit a 
 
27

 
proven re-offence than older adults, and older juveniles are more likely to 
re-offend than younger juveniles.  
 
Index offence 
The index offence represents the offence that led to the offender entering 
the cohort. Index offences were classified into 21 broad categories and their 
relative coefficients are shown in relation to the reference category violence. 
To ensure the reliability and replicability of the model coefficients, any index 
offences with low numbers were grouped with the ‘other’ index offence 
group. 
 
Ethnicity 
Ethnicity is derived from the PNC and reflects the officer’s view of the 
offender’s ethnicity.  Thus, ethnicity in this model should be taken as a proxy 
for the actual ethnicity and the results should not be over-interpreted 
because any biases in the assessment are unknown.  Ethnicity was a 
statistically significant factor, making it an important factor to control for and 
therefore it was included in the model. 
 
Copas rate 
The Copas rate (Copas and Marshall, 1998) controls for the rate at which an 
offender has built up convictions throughout their criminal career.  The 
higher the rate, the more convictions an offender has in a given amount of 
time, and the more likely it is that an offender will be re-convicted.  
The Copas rate formula is: 









10
 
 
years
in 
career 
 
criminal
 
of
Length 
1
 
cautions
or 
 s
appearance
court 
 
of
Number 
log
 
rate
 
copas
e
 
 
For adults the copas rate is included as a linear and quadratic, but for 
juveniles it is included as a linear term only. As mentioned above, inclusion 
of variables was heavily influenced by their statistical significance.  
 
Length of criminal career 
An offender’s criminal career is a significant factor in predicting the 
likelihood of a re-offence and this relationship is quadratic, thus both linear 
and quadratic terms were included in the model.  
 
Total number of previous offences 
The total number of previous offences is a significant factor in predicting the 
likelihood of a re-offending.  The previous offending variables counted 
cautions and convictions and were included as linear and logged variables. 
 
 
28

 
Previous custodial sentences 
For adults, the number of previous custodial sentences was implemented as 
a continuous variable in both linear and quadratic terms. For juveniles, 
previous custodial sentences were included as a binary term: had the 
offender received one or more previous custodial sentences, yes or no. The 
difference in treatment reflects the more limited custodial history juvenile 
offenders generally possess compared to adult offenders.  
 
Counts of previous offending by type of offence 
For adults, the number of previous offences by type of offence was an 
improvement over simple ‘yes or no’ variables for recording the presence of 
prior offences in the relevant categories. For juvenile offenders, simple ‘yes 
or no’ variables for recording the presence of prior offences in the relevant 
categories performed better. The difference in treatment reflects the more 
limited offending history juvenile offenders generally possess compared to 
adult offenders.  
 
Interaction terms 
Interaction terms are calculated by multiplying two factors together. The 
inclusion of these terms allows the effect of one variable to vary according 
to the values of another, improving the quality of predictions. This is 
important because three factors (gender, age and total number of previous 
offences) are not completely independent of each other. 
 
For adults, interaction terms were also included for drug-misusing offenders 
as they showed some trends in their proven re-offending behaviour that 
were different from the more general offending population.   
 
Model assessment 
The model is assessed by calculating the level of discrimination between 
offenders that committed a proven re-offence and offenders that did not.  
The adult logistic regression model achieved a 78.9 per cent overall 
discrimination level on the 2008 cohort and 72.4 per cent for the juvenile 
logistic regression model. A level of discrimination of about 70% was 
deemed to be acceptable and the model should predict results accurately 
enough for the predicted rate to be used.  The discrimination can also be 
evaluated by calculating the Area Under Curve (AUC) for the Receiver 
Operator Characteristic curve.  Again, the value for the model was .784 for 
the adult regression model in 2008 and .716 for the youth regression model 
which means a satisfactory level of discrimination (Hosmer and Lemeshow, 
2000, p.162). 
 
29

 
Coefficients of the 2008 statistical model 
The following tables (2 and 3) show the parameter estimates for the various 
components of the logistic regression model for the predicted one-year 
proven re-offending rates for adults and young offenders. 
  
Each logistic coefficient is multiplied by the variable value for each offender 
to calculate a linear prediction.  To calculate each offender’s predicted 
probability of committing a proven re-offence in the follow-up period or a 
further 6 month waiting period we transform the linear prediction Z using the 
following formula: 
)
exp(
1
)
exp(
g
Reoffendin
 
of
y 
Probabilit
 
Predicted
Z
Z


 
The exponent of the coefficient is the odds ratio of committing a proven re-
offence corresponding to the particular coefficient and enables us to make 
comparisons between different categories.  For factors with interactions 
(e.g. age and gender) the interpretation is more complex. 
 
The significance (p-value) gives us an assessment of how significant each 
variable is in predicting the likelihood of an offender to commit a proven re-
offence within one year.  For modelling purposes, a probability value (p-
value) of less than 0.05 is considered to be significant. 
 
30

 
Table 2: List of variables in the logistic regression model applied to 
the 2008 data on adult offenders and their respective coefficients  
 
Variables
Coefficient
Logs-odd 
ratios
P-value
Variables
Coefficient Logs-odd 
ratios
P-value
Constant
1.940
6.958
0.000
Index offence:
Violence
Gender:
Robbery
-0.361
0.697
0.000
Female 
Theft
0.482
1.620
0.000
Male
0.645
1.906
0.000
Handling
0.173
1.189
0.000
Taking and driving away
0.180
1.198
0.000
Age:
Sexual child
-0.465
0.628
0.000
Age
-0.250
0.779
0.000
Public order
0.220
1.247
0.000
Age squared
0.006
1.006
0.000
Soliciting/prostitution
0.253
1.288
0.000
Age cubed
-0.00004
1.000
0.000
Domestic burglary
0.148
1.159
0.000
Male * age interaction
-0.013
0.988
0.000
Other burglary
0.337
1.401
0.000
Theft from vehicles
0.478
1.612
0.000
General criminal career variables:
Drink driving
-0.154
0.857
0.000
Previous offences
-0.006
0.994
0.000
Criminal damage 
0.226
1.254
0.000
Previous offences (logged)
0.391
1.478
0.000
Drug supply
-0.400
0.670
0.000
Male * previous offences interaction
-0.003
0.997
0.000
Drug possession
0.074
1.077
0.000
Previous prison sentences
0.045
1.046
0.000
Drug test
-1.167
0.311
0.000
Previous prison sentences (logged)
-0.060
0.942
0.000
Fraud/forgery
-0.213
0.808
0.000
Career length
-0.0001
1.000
0.000
Absconding and bail 
0.364
1.440
0.000
Career length squared
0.000
1.000
0.069
Copas rate
0.385
1.469
0.000
Number of previous offences:
Copas rate squared
-0.064
0.938
0.000
Public order
0.052
1.053
0.000
PPO offender
0.528
xx-xxxx-xxxx
0.000
Sexual
0.035
1.036
0.000
Drug-misusing offender
1.422
4.146
0.000
Domestic burglary
-0.006
0.994
0.005
Theft
0.012
1.012
0.000
Ethnicity: 
Handling
-0.010
0.990
0.002
White
Absconding and bail 
0.018
1.018
0.000
Unknown 
-0.663
0.516
0.000
Taking and driving away
-0.007
0.993
0.003
White other
0.324
1.383
0.000
Criminal damage 
0.017
1.017
0.000
Black
0.161
1.175
0.000
Drug supply
-0.044
0.957
0.000
Pacific 
0.210
1.233
0.000
Drug possession
0.013
1.013
0.000
Middle East
0.130
1.138
0.003
Other 
-0.002
0.998
0.073
Interaction with drug-misusing 
offenders: 
Previous offences (logged)
-0.156
0.855
0.000
Index offence of drug supply
-0.430
0.651
0.000
Index offence of drug 
possession
-0.550
0.577
0.000
Reference category
Reference category
Reference category
 
 
31

 
Table 3: List of variables in the logistic regression model applied to 
the 2008 data on young offenders and their respective coefficients 
Variables
Coefficient
Logs-odd 
ratios
P-value
Variables
Coefficient
Logs-odd 
ratios
P-value
Constant
-1.495
0.224
0.000
Index offence:
Violence
Gender:
Robbery
0.130
1.139
0.003
Female 
Public order or riot
0.178
1.195
0.000
Male
0.527
xx-xxxx-xxxx
0.000
Sexual offences
-0.578
0.561
0.000
Sexual offences against children
-1.157
0.314
0.000
Age:
Domestic burglary
0.233
1.262
0.000
Aged 10-11
Other burglary
0.083
1.087
0.026
Aged 12
0.354
1.425
0.000
Theft
-0.088
0.916
0.000
Aged 13
0.448
1.566
0.000
Handling
0.118
1.126
0.018
Aged 14
0.431
1.538
0.000
Fraud or forgery
-0.251
0.778
0.000
Aged 15
0.186
1.205
0.000
Absconding or bail offences
0.176
1.192
0.022
Aged 16
-0.124
0.883
0.017
Taking and driving away
0.116
1.123
0.003
Aged 17
-0.202
0.817
0.000
Theft from vehicles
0.264
1.302
0.000
Drunk driving
-0.488
0.614
0.000
Interactions between age and gender:
Female at any age
Any previous offences:
Male aged 10-11
Violence
0.039
1.039
0.062
Male aged 12
-0.276
0.759
0.000
Robbery
0.101
1.106
0.011
Male aged 13
-0.214
0.807
0.000
Public order or riot
0.143
1.154
0.000
Male aged 14
-0.157
0.855
0.000
Domestic burglary
0.166
1.181
0.000
Male aged 16
0.134
1.144
0.002
Other burglary
0.099
1.104
0.001
Male aged 17
0.113
1.120
0.013
Theft
0.135
1.144
0.000
Handling
0.107
1.113
0.009
General criminal career variables:
Absconding or bail offences
0.096
1.101
0.032
Career length
0.000
1.000
0.000
Taking and driving away
0.088
1.093
0.012
Career length squared
0.000
1.000
0.000
Theft from vehicles
0.125
1.133
0.012
Copas rate
0.128
1.137
0.001
Drunk driving
-0.245
0.783
0.033
Previous offences
-0.036
0.964
0.000
Criminal or malicious damage
0.069
1.071
0.001
Previous offences (logged)
0.920
2.510
0.000
Other
0.138
1.148
0.001
Previous prison sentence(s)
0.124
1.132
0.022
Miscellaneous
-0.689
0.502
0.014
PPO offender
0.930
2.534
0.000
Breaches
0.762
2.144
0.007
Ethnicity: 
White
Unknown
-0.823
0.439
0.000
White (other)
0.196
1.217
0.000
Black
0.187
1.206
0.000
Asian
-0.200
0.819
0.000
Pacific
-0.468
0.626
0.001
Reference category
Reference category
Reference category
Reference category
Reference category
Reference category
 
32

 
Additional modelling for prison performance 
Assessing the performance of individual prisons in reducing re-offending is 
difficult because the particular characteristics of offenders that are at a 
particular prison are likely to be the main drivers behind re-offending.  
A statistical methodology has been developed to examine prison re-
offending rates that not only takes account of offence, offender and prison 
characteristics, but also takes account of the hierarchical structure of the 
data; i.e. that offenders are within prisons.  
Two separate models were developed: for prisoners receiving sentences of 
fewer than 12 months and prisoners with sentences of 12 months or over. 
The separate models for prisoners with sentences of fewer than 12 months 
and 12 months or more reflects differences in prisoners’ re-offending 
behaviour by prison sentence length.  
The model used for both types of offender was a logistic regression model 
with mixed effects (fixed and random). The outcome variable is a binary 
yes/no variable representing whether an offender re-offends or not. 
Offender characteristics are included as fixed independent variables and the 
prisons are included as a random effect component which allows each 
prison to interact with the fixed effects differently.  
The variables included in the model were similar to those used to develop 
the adjusted baseline described above: age, ethnicity, index offence, 
previous offences, previous prison sentences, copas scores, and criminal 
career, as well as the random effects component of prisons. The goodness-
of-fit by AUC was satisfactory, above 0.77 in all cases. 
Considerable preliminary analysis has been undertaken investigating the 
relative important of offence, offender and prison-level variables in 
explaining custodial re-offending. This analysis has overwhelmingly shown 
that offence and offender-level variables shape re-offending whereas 
prison-level variables refine re-offending behaviour. For this reason, the 
model uses offender and offence-level variables and only models prison-
level effects using a single random effects component.     
This model generates an expected probability of re-offending for each 
offender. When aggregated up to the prison it produces an expected 
proportion of offenders who re-offend. This can be compared with the actual 
rate of re-offending.  
Where the model-predicted re-offending rate was statistically significantly 
different to actual re-offending rates, two possible explanations are 
plausible: 
1. Missing characteristics: it is possible that there are underlying 
offence, offender or prison characteristics affecting re-offending 
behaviour that are not included in the current model; or, 
 
33

 
2. A genuine difference: there is something specific to these prisons 
that make them better/worse than predicted. 
 
Additional modelling for probation performance 
Results in the headline measure are compared to a baseline rate, adjusted 
for changes in the offender profile. This relies on an estimate of the 
relationship between offender characteristics and proven re-offending 
behaviour over twelve-months. An equivalent estimate has been carried out 
for the proven re-offending behaviour specifically of offenders commencing 
court orders. This uses the same variables as the headline measure plus 
additional variables to ensure that the actual and predicted rates are 
identical for every probation trust in the baseline period (2008). The tables 
accompanying the report present the adjusted baseline for each trust. 
Differences between the prison and probation trusts models and the 
model for the adjusted baseline for the headline measure 
 The adjusted baseline for the headline measure applies to all 
offenders; the prison and probation models only apply to offenders 
discharged from custody or given a Court Order. 
 The adjusted baseline for the headline measure is created using a 
fixed effects model using only offender and offence level variables; 
the probation model does the same, but the prison models use 
offender and offence level variables and also include a random 
component to reflect that prisoners are located within prisons. 
 The adjusted baseline for the headline measure and for the probation 
model is derived using data from a baseline year (2008). The 
observed re-offending is equal to the predicted re-offending for the 
baseline year; the model coefficients are then applied to subsequent 
years and the predicted rates begins to differ from the actual rates. 
Provided the baseline year model is frequently refreshed, this 
ensures that any deviations of the actual re-offending rate from the 
predicted rate are due to system changes and not due to changes in 
the cohort make up. This approach enables us to assess progress in 
reducing re-offending.  
 
Whereas, the prison model are generated from scratch every year 
and assess if any prison or probation trust differs from the national 
average. As with the previous approach, the observed re-offending 
rate is still equal to the predicted re-offending for the prison 
population as a whole. It will not necessarily be the case for individual 
prisons. This approach provides an idea of which prisons have 
significantly lower (or higher) re-offending rates than predicted.  
 
Work is underway to develop an equivalent model for probation trusts 
to the one used for prisons. 
 
34

 
Appendix A: List of serious offences  
Serious violence against the person 
1.  Murder:  
1. 
Of persons aged 1 year or over. 
2. 
Of infants under 1 year of age. 
 
2. 
Attempted murder.  
 
4. 
Manslaughter, etc:  
1. 
Manslaughter. 
2. 
Infanticide. 
3. 
Child destruction. 
 
 
   
 
 
 
5. 
Wounding or other act endangering life: 
1. 
Wounding, etc. with intent to do grievous bodily harm, etc. or to resist 
apprehension. 
2. 
Shooting at naval or revenue vessels. 
4. 
Attempting to choke, suffocate, etc. with intent to commit an indictable offence 
(garrotting). 
5. 
Using chloroform, etc. to commit or assist in committing an indictable offence. 
6. 
Burning, maiming, etc. by explosion. 
7. 
Causing explosions or casting corrosive fluids with intent to do grievous bodily 
harm. 
8. 
Impeding the saving of life from shipwreck. 
9. 
Placing, etc. explosives in or near ships or buildings with intent to do bodily 
harm, etc. 
10. Endangering life or causing harm by administering poison. 
11. Causing danger by causing anything to be on road, interfering with a vehicle or 
traffic equipment. 
13. Possession, etc. of explosives with intent to endanger life. 
14. Possession of firearms, etc. with intent to endanger life or injure property, etc. 
(Group I). 
15. Possession of firearms, etc. with intent to endanger life or injure property, etc. 
(Group II). 
16. Possession of firearms, etc. with intent to endanger life or injure property, etc. 
(Group III). 
17. Using, etc. firearms or imitation firearms with intent to resist arrest, etc. (Group 
I). 
18. Using, etc. firearms or imitation firearms with intent to resist arrest, etc. (Group 
II). 
19. Using, etc. firearms or imitation firearms with intent to resist arrest, etc. (Group 
III). 
 
[Group I - Firearms, etc. other than as described in Group II or III. 
 
Group II - Shotguns as defined in s.1 (3)(a) of the Firearms Act 1968. 
 
Group III - Air weapons as defined in s.1 (3)(b) of the Firearms Act 1968] 
20. Use etc. of chemical weapons. 
21. Use of premises or equipment for producing chemical weapons. 
22. Use, threat to use, production or possession of a nuclear weapon. 
23. Weapons related acts overseas. 
24. Use of noxious substances or things to cause harm or intimidate. 
25. Performing an aviation function or ancillary function when ability to carry out 
function is impaired because of drink or drugs. 
26. Endangering safety at sea/aerodromes. 
27. Torture. 
 
8. 
Other wounding, etc: 
 
35

 
1. 
Wounding or inflicting grievous bodily harm (inflicting bodily injury with or without 
weapon).  
33. Racially aggravated wounding or inflicting grievous bodily harm (inflicting bodily 
injury with or without weapon). 
40. Religiously aggravated malicious wounding or GBH. 
46. Racially or religiously aggravated malicious wounding or grievous bodily harm. 
 
Sexual offences 
17. Sexual assault on a male (previously indecent assault on a male): 
11. Indecent assault on male person under 16 years. 
12. Indecent assault on male person 16 years or over.  
13. Assault on a male by penetration.  
14. Assault of a male child under 13 by penetration. 
15. Sexual assault on a male. 
16. Sexual assault of a male child under 13. 
 
19. Rape: 
2. 
Man having unlawful sexual intercourse with a woman who is a defective. 
3. 
Male member of staff of hospital or mental nursing home having unlawful sexual 
intercourse  with female patient. 
4. 
Man having unlawful sexual intercourse with mentally disordered female patient 
who is subject to his care. 
7. 
Rape of a female aged under 16. 
8. 
Rape of a female aged 16 or over. 
9. 
Rape of a male aged under 16. 
10. Rape of a male aged 16 or over. 
11. Attempted rape of a female aged under 16. 
12. Attempted rape of a female aged 16 or over. 
13. Attempted rape of a male aged under 16. 
14. Attempted rape of a male aged 16 or over. 
16. Rape of female child under 13 by a male. 
17. Rape of a male child under 13 by a male. 
18. Attempted rape of a female child under 13 by a male 
19. Attempted rape of a male child under 13 by a male  
 
20. Sexual assault on female (previously indecent assault on a female): 
1. 
On females under 16 years of age. 
2. 
On females aged 16 years and over. 
3. 
Assault on a female by penetration.  
4. 
Assault on a female child under 13 by penetration. 
5. 
Sexual assault on a female.  
6. 
Sexual assault on a female child under 13. 
 
21. Sexual activity (male and female) (including with a child under 13) (previously unlawful 
intercourse with a girl under 13): 
2. 
Causing or inciting a female child under 13 to engage in sexual activity - 
penetration.  
3. 
Causing or inciting a female child under 13 to engage in sexual activity - no 
penetration. 
4. 
Causing or inciting a male child under 13 to engage in sexual activity - 
penetration   
5. 
Causing or inciting a male child under 13 to engage in sexual activity - no 
penetration. 
6. 
Sexual activity with a female child under 13 - offender aged 18 or over - 
penetration. 
7. 
Sexual activity with a male child under 13 - offender aged 18 or over - 
penetration. 
8. 
Causing or inciting a female child under 13 to engage in sexual activity - 
offender aged 18 or over - penetration 
9. 
Causing or inciting a male child under 13 to engage in sexual activity - offender 
aged 18 or over - penetration. 
 
36

 
10. Engaging in sexual activity in the presence of a child under 13 (offender aged 
18 or over). 
11. Causing a child under 13 to watch a sexual act (offender aged 18 or over). 
12.   Sexual activity with a female child under 13 - offender aged under 18. 
13.   Sexual activity with a male child under 13 - offender aged under 18. 
14.   Causing of inciting a female child under 13 to engage in sexual activity - 
offender under 18. 
15. Causing or inciting a male child under 13 to engage in sexual activity - offender 
under 18.  
16. Engaging in sexual activity in the presence of a child under 13 - offender under 
18. 
17. Causing a child under 13 to watch a sexual act - offender under 18. 
18. Sexual activity with a female under 13 - offender aged 18 or over - no 
penetration. 
19. Sexual activity with a male child under 13 - offender aged 18 or over - no 
penetration. 
20. Causing or inciting a female child under 13 to engage in sexual activity - 
offender aged 18 or over - no penetration. 
21. Causing or inciting a male child under 13 to engage in sexual activity - offender 
aged 18 or over - no penetration. 
22. Sexual activity with a female child under 13 - offender aged under 18 - no 
penetration. 
23. Sexual activity with a male child under 13 - offender aged under 18 - no 
penetration. 
24. Causing or inciting a female child under 13 to engage in sexual activity - 
offender aged under 18 - no penetration. 
25. Causing or inciting a male child under 13 to engage in sexual activity - offender 
aged under 18 - no penetration. 
 
 22. Sexual activity (male and female) (including with a child under 16) (previously unlawful 
sexual intercourse with a girl under 16): 
0. 
Unlawful sexual intercourse with girl under 16 (offences committed prior to 1 
May 2004). 
2. 
Causing a female person to engage in sexual activity without consent - 
penetration 
3. 
Causing a male person to engage in sexual activity without consent - 
penetration 
4. 
Causing a female person to engage in sexual activity without consent - no 
penetration. 
5. 
Causing a male person to engage in sexual activity without consent - no 
penetration. 
6. 
Sexual activity with a female child under 16 (offender aged 18 or over) - 
penetration 
7. 
Sexual activity with a male child under 16 (offender aged 18 or over) - 
penetration 
8. 
Causing or inciting a female child under 16 to engage in sexual activity (offender 
aged 18 or over) - penetration 
9. 
Causing of inciting a male child under 16 to engage in sexual activity (offender 
aged 18 or over) - penetration 
10. Engaging in sexual activity in the presence of a child under 16 (offender aged 
18 or over). 
11. Causing a child under 16 to watch a sexual act (offender aged 18 or over). 
18. Sexual activity with a female child under 16 - offender aged 18 or over - no 
penetration. 
19. Sexual activity with a male child under 16 - offender aged 18 or over - no 
penetration. 
20. Causing or inciting a female child under 16 to engage in sexual activity (offender 
aged 18 or over) - no penetration. 
21. Causing or inciting a male child under 16 to engage in sexual activity (offender 
aged 18 or over) - no penetration. 
 
 
70. Sexual activity etc. with a person with a mental disorder: 
 
37

 
1. 
Sexual activity with a male person with a mental disorder impeding choice – 
penetration. 
2. 
Sexual activity with a female person with a mental disorder impeding choice – 
penetration. 
3. 
Sexual activity with a male person with a mental disorder impeding choice - no 
penetration. 
4. 
Sexual activity with a female person with a mental disorder impeding choice - no 
penetration. 
5. 
Causing or inciting a male person with a mental disorder impeding choice to 
engage in sexual activity – penetration. 
6. 
Causing or inciting a female person with a mental disorder impeding choice to 
engage in sexual activity – penetration. 
7. 
Causing or inciting a male person with a mental disorder impeding choice to 
engage in sexual activity – penetration. 
8. 
Causing or inciting a female person with a mental disorder impeding choice to 
engage in sexual activity - no penetration. 
9. 
Engaging in sexual activity in the presence of a person with a mental disorder 
impeding choice. 
10. Causing a person with a mental disorder impeding choice to watch a sexual act. 
11. Inducement, threat or deception to procure sexual activity with a person with a 
mental disorder – penetration. 
12. Inducement, threat or deception to procure sexual activity with a person with a 
mental disorder - no penetration. 
13. Causing a person with a mental disorder to engage in sexual activity by 
inducement, threat or deception - penetration. 
14. Causing a person with a mental disorder to engage in sexual activity by 
inducement, threat or deception - no penetration. 
15. Engaging in sexual activity in the presence, procured by inducement, threat or 
deception, of a person with a mental disorder. 
16. Causing a person with a mental disorder to watch a sexual act by inducement, 
threat or deception. 
17. Care workers: Sexual activity with a male person with a mental disorder - 
penetration. 
18. Care workers: Sexual activity with a female person with a mental disorder - 
penetration. 
19. Care workers: Sexual activity with a male person with a mental disorder - no 
penetration. 
20. Care workers: Sexual activity with a female person with a mental disorder - no 
penetration. 
21. Care workers: Causing or inciting sexual activity (person with  a mental disorder) 
- penetration. 
22. Care workers: Causing or inciting sexual activity (person with a mental disorder) 
- no penetration. 
23. Care workers: Sexual activity in the presence of a person with a mental 
disorder. 
24. Care workers: Causing a person with a mental disorder impeding choice to 
watch a sexual act. 
 
71. Abuse of children through prostitution and pornography (previously child prostitution 
and pornography): 
1. 
Arranging or facilitating the commission of a child sex offence. 
2. 
Paying for sex with a female child under 13 - penetration  
3. 
Paying for sex with a male child under 13 - penetration  
4. 
Paying for sex with a female child under 16 - no penetration 
5. 
Paying for sex with a male child under 16 - no penetration 
6. 
Paying for sex with a female child aged 16 or 17. 
7. 
Paying for sex with a male child aged 16 or 17. 
8. 
Causing or inciting child prostitution or pornography - child aged 13-17. 
9. 
Controlling a child prostitute or a child involved in pornography - child aged 13-
17. 
10. Arranging or facilitating child prostitution or pornography - child aged 13-17. 
11. Causing or inciting child prostitution or pornography - child under 13. 
 
38

 
12. Controlling a child prostitute or child involved in pornography - child under 13. 
13. Arranging or facilitating child prostitution or pornography - child under 13.  
14. Paying for sex with a female child aged under 16 - penetration 
15. Paying for sex with a male child aged under 16 - penetration 
 
72. Trafficking for sexual exploitation: 
1. 
Arranging or facilitating arrival of a person into the UK for sexual exploitation 
(trafficking). 
2. 
Arranging or facilitating travel of a person within the UK for sexual exploitation 
(trafficking). 
3. 
Arranging or facilitating departure of a person from the UK for sexual 
exploitation (trafficking). 
 
Taking and driving away and related offences 
37. Aggravated vehicle taking: 
1. 
Where, owing to the driving of the vehicle, an accident occurs causing the death 
of any person. 
 
Other motoring offences 
4. 
Manslaughter, etc:  
4. 
Causing death by dangerous driving. 
8. 
(Offences) Causing death by careless or inconsiderate driving (Offences due to 
commence in Autumn 2007). 
 
Drink driving offences 
4. 
Manslaughter, etc:  
6. 
Causing death by careless driving when under the influence of drink or drugs. 
 
 
39

 
Serious acquisitive offences  
 
Burglary  
 
1. Burglary in a dwelling with intent to commit or the commission of an offence 
triable only on indictment.  
2. Burglary in a dwelling with violence or the threat of violence.  
3. Other burglary in a dwelling. 
4. Aggravated burglary in a dwelling (including attempts )  
 
Robbery  
1. Robbery  
2. Assault with intent to rob.  
 
Taking and driving away  
1. Aggravated taking where the vehicle was driven dangerously on a road or other 
public place  
 
2. Aggravated taking where owing to the driving of the vehicle an accident occurred  
causing injury to any person or damage to any property other than the vehicle  
 
Theft from or of vehicles  
1. Stealing from motor vehicles.  
2. Stealing from other vehicles.  
3. Theft of motor vehicle.  
4. Unauthorised taking of a motor vehicle   
 
.  
 
40

 
Appendix B: Glossary of Terms 
 
Re-offending terms 
Cohort  - this is the group of individuals whose re-offending is measured.  
 
Index offence - the index offence is the proven offence that leads to an 
offender being included in the cohort.  
 
Index disposal - the index disposal of the offender is the type of sentence 
the offender received for their index offence. 
 
Start point (also known as the index date) - this is the set point in time 
from when re-offences are measured.  
 
Follow up period - this is the length of time proven re-offending is 
measured over.  
 
Waiting period - this is the additional time beyond the follow up period to 
allow for offences committed towards the end of the follow up period to be 
proved by a court conviction, caution, reprimand or final warning.  
 
Adjusted baseline - proven re-offending is related to the characteristics of 
offenders which means that any overall rate of proven re-offending will 
depend, in part, on the characteristics of offenders coming into the system 
(just as the examination pass rate of a school will be related to the 
characteristics of its pupils).  We use a modelling technique to produce a 
baseline figure adjusted to match the characteristics of the cohort we are 
comparing. For more details see the chapter on Statistical modelling and 
coefficients.  
 
Reconviction – where an offender is convicted at court for an offence 
committed within a set follow up period and convicted within either the follow 
up period or waiting period 
 
Proven re-offence – where an offender is convicted at court or receives 
some other form of criminal justice sanction for an offence committed within 
a set follow up period and disposed of within either the follow up period or 
waiting period.  
 
Cohort definitions used in the Proven Re-offending statistic quarterly 
bulletin in England and Wales publication  
The proven re-offending cohort consists of all offenders discharged from 
custody, otherwise sanctioned at court, receiving a caution, reprimand or 
warning or tested positive for opiates or cocaine in each year.  This cohort’s 
criminal history is collated and criminal behaviour is tracked over the 
following one year. Any offence committed in this one-year period which is 
proven by a court conviction or out-of-court disposal (either in the one-year 
 
41

 
period, or in a further six months waiting period) counts as a proven re-
offence.  
The latest available publication is the Proven Re-offending statistic quarterly 
bulletin in England and Wales; Ministry of Justice, October 2011.  
Cohort definitions used in the Local Measure of Re-offending quarterly 
bulletin publication  
The local adult re-offending measure takes a snapshot of all offenders, aged 
18 or over, who are under probation supervision at the end of a quarter, and 
combines four such snapshots together.  
This cohort’s criminal history is collated and criminal behaviour is tracked 
over the following three months. Any offence committed in this three month 
period which is proven by a court conviction or out-of-court disposal (either 
in the three month period, or in a further three months waiting period) counts 
as a proven re-offence.  
Results from this publication are available at 
www.justice.gov.uk/publications/statistics-and-data/reoffending/local-adult-
reoffending.htm 
Cohort definitions used in the previous Adult re-convictions in 
England and Wales publication  
The adult re-conviction cohort consists of adults discharged from custody or 
commencing a court order under probation supervision in the first quarter of 
each year. This cohort’s criminal history is collated and criminal behaviour is 
tracked over the following one year. Any offence committed in this one-year 
period which is proven by a court conviction (either in the one-year period, 
or in a further six months waiting period) counts as a reconviction.  
The last publication in this series is the Adult re-convictions: results from the 
2009 cohort; Ministry of Justice, March 2011.  
www.justice.gov.uk/publications/statistics-and-data/reoffending/adults.htm 
Cohort definitions used in the previous Re-offending of juveniles in 
England and Wales publication  
The juvenile reoffending cohort is formed of juvenile offenders discharged 
from custody, otherwise sanctioned at court, or receiving a reprimand or 
warning in January to March of each year. This cohort’s criminal history is 
collated and criminal behaviour is tracked over the following one year. Any 
offence committed in this one-year period which is proven by a court 
conviction or out-of-court disposal (either in the one-year period, or in a 
further six months waiting period) counts as proven reoffending.  
The last publication in this series is the Reoffending of juveniles: results 
from the 2009 cohort; Ministry of Justice, March 2011.  
http://www.justice.gov.uk/publications/statistics-and data/reoffending 
/juveniles.htm 
 
42

 
Disposals (Sentences) 
Fine  
A financial penalty imposed following conviction.  
Court orders  
Court orders include community sentences, community orders and 
suspended sentence orders supervised by the Probation Service. They do 
not include any pre or post release supervision.  
Criminal Justice Act 2003 (CJA03)  
For offences committed on or after 4 April 2005, the new community order 
replaced all existing community sentences for adults. The Act also 
introduced a new suspended sentence order for offences which pass the 
custody threshold. It also changed the release arrangements for prisoners. 
See Appendix A of Offender Management Caseload Statistics96 for more 
information.  
Community order  
For offences committed on or after 4 April 2005, the new community order 
introduced under the CJA 2003 replaced all existing community sentences 
for those aged 18 years and over. This term refers to all court orders except 
suspended sentence orders and deferred sentences which may have a 
custodial component to the sentence. The court must add at least one (but 
could potentially comprise of all 12) requirements depending on the 
offences and the offender. The requirements are:  
 unpaid work (formerly community service/community punishment) – a 
requirement to complete between 40 and 300 hours’ unpaid work;  
 
 activity – for example, to attend basic skills classes;  
 
 programme – there are several designed to reduce the prospects of 
reoffending;  
 
 prohibited activity – a requirement not do so something that is likely 
to lead to further offender or nuisance;  
 
 curfew – which is electronically monitored;  
 
 exclusion – this is not used frequently as there is no reliable 
electronic monitoring yet available;  
 
 residence – requirement to reside only where approved by probation 
officer;  
 
 mental health treatment (requires offender’s consent);  
 
43

 
 
 drug rehabilitation (requires offender’s consent);  
 
 alcohol treatment (requires offender’s consent);  
 
 supervision – meetings with probation officer to address 
needs/offending behaviour; and,  
 
 attendance centre – three hours of activity, between a minimum of 12 
hours and a maximum of 36 in total.  
 
Typically, the more serious the offence and the more extensive the 
offender’s needs, the more requirements there will be. Most orders will 
comprise one or two requirements but there are packages of several 
requirements available where required. The court tailors the order as 
appropriate and is guided by the Probation Service through a pre-sentence 
report.  
Suspended Sentence Order (SSO)  
The Criminal Justice Act 2003 introduced a new suspended sentence order 
which is made up of the same requirements as a community order and, in 
the absence of breach is served wholly in the community supervised by the 
Probation Service. It consists of an ‘operational period’ (the time for which 
the custodial sentence is suspended) and a ‘supervision period’ (the time 
during which any requirements take effect). Both may be between six 
months and two years and the ‘supervision period’ cannot be longer than 
the ‘operational period’, although it may be shorter. Failure to comply with 
the requirements of the order or commission of another offence will almost 
certainly result in a custodial sentence.  
Pre CJA03 Court Orders - Community sentences: 
Community punishment order (CPO): the offender is required to 
undertake unpaid community work.  
 
Community rehabilitation order (CRO): a community sentence which may 
have additional requirements such as residence, probation centre 
attendance or treatment for drug, alcohol or mental health problems.  
 
Community punishment and rehabilitation order (CPRO): a community 
sentence consisting of probation supervision alongside community 
punishment, with additional conditions like those of a community 
rehabilitation order.  
 
Drug treatment and testing order (DTTO): a community sentence 
targeted at offenders with drug misuse problems.  
 
Custody - the offender is awarded a sentence to be served in prison or YOI 
(Youth Offenders Institute). If the offender was given a sentence of 12 
months or over, or was aged under 22 on release, the offender is 
supervised by the Probation Service on release. It is important to note that 
 
44

 
the sentence length awarded will be longer than the time served. For more 
information please refer to Appendix A of the Offender Management 
Caseload Statistics.  
Prison categories  
Category B and Category C prisons hold sentenced prisoners of their 
respective categories, including life sentenced prisoners. The regime 
focuses on programmes that address offending behaviour and provide 
education, vocational training and purposeful work for prisoners who will 
normally spend several years in one prison.  
 
High Security Prisons hold Category A and B prisoners. Category A 
prisoners are managed by a process of dispersal, and these prisons also 
hold a proportion of Category B prisoners for whom they provide a similar 
regime to a Category B prison. The Category B prisoners held in a High 
Security Prison are not necessarily any more dangerous or difficult to 
manage than those in category B prisons.  
 
Female prisons. As the name implies, they hold women prisoners. 
Because of the smaller numbers, they are not divided into the same number 
of categories although there are variations in security levels.  
 
Local prisons serve the courts in the area. Historically their main function 
was to hold unconvicted and unsentenced prisoners and, once a prisoner 
had been sentenced, to allocate them on to a Category B, C or D prison as 
appropriate to serve their sentence. However, pressure on places means 
that many shorter term prisoners serve their entire sentence in a local 
prison, while longer term prisoners also complete some offending behaviour 
and training programmes there before moving on to lower security 
conditions. All local prisons operate to category B security standards.  
 
Open prisons have much lower levels of physical security and only hold 
Category D prisoners. Many prisoners in open prisons will be allowed to  
go out of the prison on a daily basis to take part in voluntary or paid work in 
the community in preparation for their approaching release.  
 
Prisoner Categories  
These categories are based on a combination of the type of crime 
committed, the length of sentence, the likelihood of escape, and the danger 
to the public if they did escape. The four categories are:  
Category A prisoners are those whose escape would be highly dangerous 
to the public or national security  
 
Category B prisoners are those who do not require maximum security, but 
for whom escape needs to be made very difficult  
 
Category C prisoners are those who cannot be trusted in open conditions 
but who are unlikely to try to escape  
 
 
45

 
Category D prisoners are those who can be reasonably trusted not to try to 
escape, and are given the privilege of an open prison.  
 
Short sentences – under twelve months  
Those sentenced to under twelve months spend the first half of their 
sentence in prison and are then released and considered ‘at risk’ for the 
remaining period. This means they are under no positive obligations and do 
not report to the probation service but, if they commit a further imprisonable 
offence during the at risk period, they can be made to serve the remainder 
of the sentence in addition to the punishment for the new offence. The 
exception to this is those aged 18 to 20 who have a minimum of three 
months’ supervision on release.  
Sentences of 12 months or over  
The Criminal Justice Act 2003 created a distinction between standard 
determinate sentences and public protection sentences. Offenders 
sentenced to a standard determinate sentence serve the first half in prison 
and the second half in the community on licence.  
Miscellaneous terms 
National Probation Service  
The National Probation Service generally deals with those aged 18 years 
and over. (Those under 18 are mostly dealt with by Youth Offending Teams, 
answering to the Youth Justice Board.) They are responsible for supervising 
offenders who are given community sentences and suspended sentence 
orders by the courts, as well as offenders given custodial sentences, both 
pre and post their release.  
Police National Computer  
The Police National Computer (PNC) is the police's administrative IT system 
used by all police forces in England and Wales and managed by the 
National Policing Improvement Agency. As with any large scale recording 
system the PNC is subject to possible errors with data entry and processing. 
The Ministry of Justice maintains a database based on weekly extracts of 
selected data from the PNC in order to compile statistics and conduct 
research on reoffending and criminal histories. The PNC largely covers 
recordable offences – these are all indictable and triable-either-way 
offences plus many of the more serious summary offences. All figures 
derived from the Ministry of Justice's PNC database, and in particular those 
for the most recent months, are likely to be revised as more information is 
recorded by the police.  
 
46

 
Recordable offences  
Recordable offences are those that the police are required to record on the 
Police National Computer. They include all offences for which a custodial 
sentence can be given plus a range of other offences defined as recordable 
in legislation. They exclude a range of less serious summary offences, for 
example television licence evasion, driving without insurance, speeding and 
vehicle tax offences.  
Indictable and summary offences - Summary offences are triable only by 
a magistrates’ court. This group includes motoring offences, common 
assault and criminal damage up to £5,000. More serious offences are 
classed either as triable either way (these can be tried either at the Crown 
Court or at a magistrates’ court and include criminal damage where the 
value is £5,000 or greater, theft and burglary) or indictable (the most 
serious offences that must be tried at the Crown Court. These ‘indictable-
only’ offences include murder, manslaughter, rape and robbery).  
 Offence Group - A split of offences into twelve separate groups. A more 
detailed split of the ten indictable offence groups (violence against the 
person, sexual offences, burglary, robbery, theft and handling and stolen 
goods, fraud and forgery, criminal damage, drug offences, other indictable 
offences (excluding motoring), indictable motoring) and the two summary 
offence groups (summary non-motoring and summary motoring offence 
types).  
 
47

 
Appendix C: Comparison of the three measures of 
re-offending  
 
Figure A1 below compares how the three measures of re-offending (the 
headline proven re-offending measure, the early estimates of re-offending 
and local adult re-offending) are constructed. It shows the period over which 
the re-offending cohort is formed, the time over which re-offending is 
measured, the additional time allowed for re-offending to be proven, and the 
time taken to collect and analyse the data, and then to publish.  
 
Figure A1: how the three re-offending measures are constructed 
Jan-Mar
Apr-Jun
Jul-Sep
Oct-Dec
Jan-Mar
Apr-Jun
Jul-Sep
Oct-Dec
Jan-Mar
Apr-Jun
Jul-Sep
Oct-Dec
2009 Headline
Cohort formation 
measure
Re-offences
Re-offences proven
Data collection and analysis
Publication
Oct-11
2010 Early Estimates
Cohort formation 
measure
Re-offences
Re-offences proven
Data collection and analysis
Publication
Oct-11
Snapshot 1
Snapshot 2
Snapshot 3
Snapshot 4
Local Re-offending 
Cohort formation based on probation caseload 
snapshots at end of each quarter 
measure
Re-offences
Re-offences proven
Data collection and analysis
Publication
Nov-11
2009
2010
2011
 
 
Cohort formation 
Headline measure and early estimates: offenders enter the cohort when 
they receive a caution (adults), a final warning or reprimand (juveniles), are 
given a non-custodial conviction, are released from custody or test positive 
for cocaine or opiates in the cohort formation period shown.   
 
 
 
 
 
 
 
 
 
Local adult re-offending:  this uses a snapshot of all offenders aged 18 or 
over, who are under probation supervision at the end of a quarter, and 
combines four such  snapshots together.  
 
 
 
 
 
 
 
 
 
Re-offences  
Headline measure: A re-offence is counted if the offence occurs within the 
"Re-offences" period shown. This is within 12 months of entering the cohort.
 
 
 
 
 
 
 
 
 
 
 
Early estimates and local adult re-offending: A re-offence is counted if the 
offence occurs within 3 months of entering the cohort for the early estimates 
measure and within 3 months following each of the four caseload snapshots 
for the local re-offending measure.  
 
Re-offences proven 
 
Headline measure: For a re-offence to be counted it must also be proven 
within the "Re-offences proven" period shown. This is within 6 months of the 
re-offence. 
 
Early estimates and local adult re-offending: For a re-offence to be counted 
it must also be proven within the "Re-offences proven" period shown. This is 
within 3 months of the re-offence.  
 
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49
Contact details and further information 
 
For queries, comments or further information, please contact:  
Nick Mavron, 
Justice Statistics Analytical Services Ministry of Justice 7th floor 102 Petty France 
London SW1H 9AJ  
Email: xxx@xxx.xx 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
© Crown copyright 
Produced by the Ministry of Justice 
Alternative formats are available on request from 
xxx@xxx.xx