Bureau of Justice Statistics Research and Development Series

Police-Public Contact Survey: 

Assessment and Recommendations for 

Producing Trend Estimates after 2011 

Questionnaire Redesign

Marcus Berzofsky, Glynis Ewing, and Matthew DeMichele

RTI International

Lynn Langton, Shelley Hyland, and Elizabeth Davis

Bureau of Justice Statistics

810 Seventh Street, N.W.

Washington, DC 20531

R&D-2017:01, NCJ 250485, April 2017

Research papers have been reviewed by Bureau of Justice Statistics (BJS) to ensure the accuracy of 

information presented and adherence to confidentiality and disclosure standards. This paper is released 

to inform interested parties about research and methodologies sponsored by BJS. Any opinions and 

conclusions expressed herein are those of the author(s) and do not necessarily represent the views of 

BJS and the U.S. Department of Justice.
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 1

Abstract

This research and development paper describes changes to the 2011 Police-Public Contact Survey 

(PPCS), a supplement to the national Crime Victimization Survey, and their impact on estimating trends.

It details how the PPCS was redesigned in 2011 to better capture police-public contacts and 

characteristics of these encounters. A split-sample design was used to assess the extent to which 

apparent changes in rates, outcomes, and perceptions of contacts with police are a product of changes 

to the survey rather than actual changes in the rates over time. The report also discusses the adjustment 

factors that were created to allow for the examination of trends between 2002 and 2011.

This project was supported by Grant No. 2011-NV-CX-K068 awarded by the Bureau of Justice Statistics, 

Office of Justice Programs, U.S. Department of Justice.
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 2

Contents

1. Introduction ..............................................................................................................................................5

1.1 Purpose of the Police-Public Contact Survey......................................................................................5

1.2 2011 PPCS redesign.............................................................................................................................5

1.3 Potential impact of questionnaire redesign on trend estimation ......................................................6

2. Understanding Estimate Differences by Questionnaire Type...................................................................7

2.1 Two approaches to eliciting police contacts.......................................................................................8

2.1.1 2008 instrument approach.............................................................................................................8

2.1.2 2011 instrument approach.............................................................................................................9

2.1.3 Additional differences between the 2011 and 2008 instruments...............................................10

2.2 Comparison of estimate types..........................................................................................................12

2.2.1 Face-to-face contact.....................................................................................................................13

2.2.2 Most recent contact and contact types.......................................................................................14

2.2.3 Use or threat of force...................................................................................................................16

2.2.4 Arrests..........................................................................................................................................19

2.2.5 Police behaved properly during contact......................................................................................20

3. Methods of Adjustment..........................................................................................................................20

3.1 Methods for comparing estimates from two instruments...............................................................20

3.1.1 Comparing estimates between the two instruments..................................................................20

3.1.2 Options for using a split-sample to adjust data ...........................................................................20

3.1.3 Method used for adjusting estimates in prior survey years........................................................21

3.2 Determining appropriate level for adjustment.................................................................................22

4. PPCS Rates Over Time.............................................................................................................................23

4.1 Estimates for which trends can be examined...................................................................................23

4.1.1 Face-to-face contact.....................................................................................................................23

4.1.2 Driver in a traffic stop as most recent contact.............................................................................25

4.1.3 Passenger in a traffic stop as most recent contact......................................................................25

4.1.4 Traffic accident as most recent contact.......................................................................................27

4.1.5 Reported crime or problem to police as most recent contact.....................................................28

4.1.6 Use or threat of force...................................................................................................................29

4.1.7 Arrest during contact ...................................................................................................................30

4.1.8 Police behaved properly...............................................................................................................31
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 3

4.2 Estimates for which trends cannot be continued.............................................................................31

4.2.1 Impact—break in series; how to interpret the estimates............................................................31

4.2.2 Most recent contact distribution .................................................................................................32

4.2.3 Characteristics and outcome estimates for all types of contact except drivers in a traffic stop.32

5. References ..............................................................................................................................................34

6. Appendix .................................................................................................................................................35

Appendix Table 1. PPCS constructs of interest and comparability categorization ...............................35

Appendix Table 2. Standard errors for Exhibits 2.3 and 3.1. Estimates by type of contact based on the 

PPCS split-sample and resulting ratio adjustment................................................................................36

Appendix Table 3. Respondents with face-to-face contact with police, by questionnaire and 

demographic characteristics, 2011 .......................................................................................................37

Appendix Table 4. Respondents who experienced arrest during their most recent contact with police, 

by questionnaire and demographic characteristics, 2011....................................................................38

Appendix Table 5. Respondents who experienced use or threat of force during the most recent 

contact, by questionnaire and demographic characteristics, 2011......................................................39

Appendix Table 6. Respondents with perceptions that police behaved properly during the most 

recent contact, by questionnaire and demographic characteristics, 2011...........................................40

Appendix Table 7. Standard errors for Figure 4.1.1. Adjusted and unadjusted rates for face-to-face 

contact, 2002–2011...............................................................................................................................41

Appendix Table 8. Estimates and standard errors for Figure 4.1.2. Adjusted and unadjusted rates for 

driver in a traffic stop, 2002–2011........................................................................................................41

Appendix Table 9. Estimates and standard errors for Figure 4.1.3. Adjusted and unadjusted rates for 

passenger in a traffic stop, 2002–2011.................................................................................................41

Appendix Table 10. Estimates and standard errors for Figure 4.1.4. Adjusted and unadjusted rates for 

traffic accident, 2002–2011 ..................................................................................................................42

Appendix Table 11. Estimates and standard errors for Figure 4.1.5. Adjusted and unadjusted rates for 

reported crime or problem to police, 2002–2011 ................................................................................42

Appendix Table 12. Estimates and standard errors for Figure 4.1.6. Adjusted and unadjusted rates for 

use or threat of force, 2002–2011 ........................................................................................................42

Appendix Table 13. Estimates and standard errors for Figure 4.1.7. Adjusted and unadjusted rates for 

arrest, 2002–2011 .................................................................................................................................43

Appendix Table 14. Estimates and standard errors for Figure 4.1.8. Adjusted and unadjusted rates for 

police behaved properly, 2002–2011 ...................................................................................................43

Appendix Table 15. Standard errors for Appendix Table 3. Respondents with face-to-face contact 

with police, by questionnaire and demographic characteristics, 2011 ................................................44
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 4

Appendix Table 16. Standard errors for Appendix Table 4. Respondents who experienced arrest 

during their most recent contact with police, by questionnaire and demographic characteristics, 

2011.......................................................................................................................................................45

Appendix Table 17. Standard errors for Appendix Table 5. Respondents who experienced use or 

threat of force during the most recent contact, by questionnaire and demographic characteristics, 

2011.......................................................................................................................................................46

Appendix Table 18. Standard errors for Appendix Table 6. Number and percent of respondents with 

perceptions that police behaved properly during most recent contact in 2011, by questionnaire and 

demographic subdomains.....................................................................................................................47
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 5

1. Introduction

1.1 Purpose of the Police-Public Contact Survey

The Bureau of Justice Statistics’ (BJS) Police-Public Contact Survey (PPCS) collects data on the 

amount and nature of residents’ formal contact with police and their perceptions of that contact. 

Respondents are asked to describe the reason for their most recent police contact, the outcome of the 

encounter, and their perceptions of police conduct. The BJS uses data from the survey to provide 

national estimates on the prevalence of police contact, the characteristics of persons with contact, 

police use of nonfatal force and stop-and-frisk tactics, perceptions of the legitimacy of police, and 

changes in these key estimates over time. The PPCS is distributed to nearly 50,000 persons age 16 or 

older as a supplement to the National Crime Victimization Survey (NCVS). From 1999 to 2008, the survey 

was administered four times—once every three years—allowing for an assessment of changes in the 

rates and nature of police contact over time. In 2011, the survey was redesigned to—

• better capture information on all types of contact between the police and public occurring 

during a 12-month period; 

• better capture information on resident-initiated contacts; 

• improve the measurement of street stops; and 

• improve the measurement of police use of force.

This report details the nature of the changes to the 2011 PPCS and the impact on trend estimation. 

The PPCS scope was altered by changing the questionnaire design, using a broader definition of police

and public contact, and asking more behaviorally specific questions about actions taken by residents and 

police. To measure the impact of these instrument changes on trends in police contact, the 2011 PPCS 

was administered to a split-sample of respondents, with about 16% of the sample receiving the original 

instrument and the other 84% receiving the revised instrument. The split-sample framework was used

to test the comparability of the 2011 items with items in prior iterations of the PPCS and to test the 

impact of measurement on 2011 rates and characteristics of police contact. The goal of this report is to 

use the 2011 split-sample design to assess the extent to which apparent changes in rates, outcomes, 

and perceptions of contacts with police are a product of instrumentation changes rather than actual 

changes in the rates over time. To the extent that changes in measurement affect trends over time, 

adjustment factors were used to assess trends from 2002 to 2011. 

1.2 2011 PPCS redesign

In 2011, the PPCS instrument was substantially revised to better capture police-public contacts and 

characteristics of these encounters. Prior to the 2011 administration of the PPCS, the BJS hosted a series 

of meetings with police experts to investigate ways to more accurately measure police-public contacts 

and police legitimacy. The resulting PPCS changes were designed to enhance respondent recollection of 

interactions with police, to collect information about a broader scope of contacts, and to gain a more 

nuanced understanding of police and public contacts. 
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 6

First, to determine if contact occurred and to enhance individuals’ recollections about their 

interactions with police over a 12-month period, BJS implemented new behaviorally specific screening 

procedures that describe a broad range of situations known to bring people in contact with police. 

Second, the scope of the PPCS was expanded to collect information about interactions that people had 

with the police that did not result in a face-to-face contact (e.g., reporting a crime to the police by 

phone or email). Third, a new set of questions was added to the instrument to collect detailed 

information about requests for police assistance (e.g., reporting a crime or non-crime emergency) and 

contacts in which the police stopped someone in a public place or on the street but not in a motor 

vehicle (known as street stops). In previous PPCS collections, both types of contact had been 

acknowledged, but respondents were not specifically asked for any details about the nature of these 

types of contact, the outcomes of the contact, or their perceptions of police behavior during the 

contact. Finally, the section on police use of force was expanded to ask respondents behaviorally specific 

questions about police actions that could later be used to classify whether force was used. 

The redesign of the PPCS also introduced several items intended to provide a more robust 

understanding of police legitimacy, including questions about police helpfulness, respondent 

satisfaction, and whether the respondent would seek police assistance for similar or different problems 

related to voluntary contacts with the police.

1.3 Potential impact of questionnaire redesign on trend estimation

The purpose of the redesign of the 2011 PPCS instrument was to enhance the data collection.

However, the changes present difficulties when estimating trends. Because of the importance of 

measuring both the level and change in police contacts, the PPCS uses a repeated survey design to allow 

for estimating changes over time in police-public contacts and the perceptions of police behavior during 

these contacts. Rather than following the same persons over time, repeated surveys generate estimates 

from different samples of respondents. In the case of the PPCS, the survey is administered to a new 

sample of respondents every three years. Duncan and Kalton (1987) refer to this as “periodic surveys”

because they are repeated at specific intervals (i.e., every three years). The PPCS is not designed to 

estimate individual-level changes in police-public contact, but rather to estimate social change for the 

overall population (Firebaugh, 1997: 3). Even if not measured perfectly, as long as measured 

consistently, trend estimates can serve as valid indicators of change. Once a redesign of an instrument 

occurs, any measurement differences between the two instruments need to be addressed to allow for 

continued trend analyses.

The PPCS provides data to document the general population trends of police-public contacts. The 

PPCS redesign presents difficulties in continuing trend analysis on key variables that are repeated 

throughout all of the PPCS iterations. Due to the existence of an established trend measured by previous 

instrument versions, any changes to questionnaire design carry a likelihood of introducing a level of 

measurement error, relative to past iterations of the survey, to the estimates of interest. In the case of a 

redesign that results in increased accuracy of the outcomes of interest, the improved survey instrument 

provides an opportunity to “calibrate the effect” of any changes to the questionnaire items (Clark et al., 

2003). Some items were unchanged and can continue to be compared over time and other items can be 

corrected with an adjustment factor, but some items are incomparable and present a break in series.
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 7

2. Understanding Estimate Differences by Questionnaire Type

The redesign of the PPCS questionnaire from 2008 to 2011 posed many challenges to estimate

comparability and trend continuation. A revised field instrument’s questionnaire items should maintain 

comparability with the previous questionnaire items despite changes in wording, formatting, or 

structure. The 2011 instrument expanded on the types of contact collected. Unfortunately, much of this 

new information was not analogous to any of the estimates available from the 2008 instrument.

Another issue surrounding the redesign resulted from changes in definitions of contact types and 

reasons for police-public contacts.

Instruments used in the 2002, 2005, and 2008 survey years focused on collecting information about 

respondents’ most recent face-to-face contact with the police in the 12 months preceding the interview 

date. Instead of focusing on only a single most recent contact, the revised 2011 instrument introduced a 

screener module of questionnaire items to capture a range of contacts with police the respondent might 

have had in the year preceding the interview date. This screener module also expanded the definition of

police-public contact to include non-face-to-face interactions (e.g., phone calls) and a wider range of 

contacts that respondents voluntarily initiated with the police (e.g., participation in a block watch). 

Though the redesigned instrument added measures of contact that had never been measured in 

previous survey years, it also measured types of contact existing in previous instruments such as street 

stops and forms of contact with police initiated by the respondent. Beyond these goals of expanding the 

types of contact included in the questionnaire, the screener module also improved the questionnaire 

design by allowing respondents to report multiple contacts that they may have had with police in the 

past year. From the contacts they reported, respondents were asked to identify the most recent contact 

with police in the 2011 instrument. Respondents were routed to an appropriate module in the 

questionnaire based on the most recent contact containing questions focused on obtaining more 

detailed information about this most recent contact. 

The two criteria a revised questionnaire item must meet to be comparable with its previous 

iteration are: (1) the items must measure the same outcome of interest either by using similar or 

identical wording or expanding upon the existing item and (2) the items must share the same 

respondent domain.

1 Based on this comparability criteria, measures from the original and redesigned 

instrument could be placed into one of three categories: (1) survey items were measuring fundamentally

different constructs (i.e., incomparably measured), (2) survey items were measuring the same 

underlying construct but differ in a way that affects the resulting estimates (i.e., similarly measured, 

adjustment needed), or (3) survey items are measuring the same construct and the manner of 

measurement did not change (i.e., similarly measured, adjustment not needed). Instrument items 

measuring fundamentally different constructs were not considered, since trend estimation is not 

possible. Items with structure or placement changes but that measured the same underlying construct 

were considered eligible to examine for trend continuation and to assess the estimates’ need for 

 1 Respondent domain refers to the group of respondents presented with the opportunity to answer the given 

questionnaire item(s) of interest.
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 8

adjustment. The items that generally remained the same in terms of the construct measured and the 

method of measurement were deemed appropriate for trend estimation.

The full list of constructs measured across the original and redesigned PPCS instruments and the 

comparability categorization are listed in Appendix Table 1. Some constructs are comparably measured 

but were not examined in this report, and these are noted as “Similarly measured, not examined” in

Appendix Table 1. This paper focuses on selected key estimates measured by the PPCS and on how to

estimate and adjust for difference due to measurement error when detected. The measures were 

chosen based on two criteria: (1) the importance of the measure and (2) known differences in how the 

construct was obtained in the two instruments. They key estimates of interest examined closely in this 

report are face-to-face contact with police in the past 12 months; contact with police as a driver in a 

traffic stop, as a passenger in a traffic stop, as a result of a traffic accident, when reporting a crime or 

problem to the police, and during arrest; and the perceptions that police behaved properly. 

2.1 Two approaches to eliciting police contacts

2.1.1 2008 instrument approach

The 2008 instrument consisted of four basic components:

1. Determining if a face-to-face contact occurred in the past 12 months,

2. Determining the use of force during the most recent face-to-face contact,

3. Determining the reason for most recent contact, and

4. Detailed modules regarding characteristics and outcomes of the most recent contact.

Determining a face-to-face contact was achieved using a combination of a singular screener item 

asking if a face-to-face contact occurred and an item on the number of face-to-face contacts. If the 

response to the screener indicated no face-to-face contact or the number of contacts was zero, the 

respondent was routed to the end of the PPCS instrument, ending the interview. Hence, if the 

respondent had a contact with police but it was not face-to-face, the 2008 instrument did not record the 

contact. If, however, the respondent reported more than one contact, they were instructed to answer 

the interview questions with only the most recent face-to-face contact in mind.

Those respondents with a face-to-face contact were then routed to the second section of the 

instrument, a series of questions on the use of force during contact. If use or threat of force was 

indicated, the respondent was asked detailed follow-up questions about the type of force, whether the 

force was excessive, and whether the respondent was injured as a result. Respondents with police 

contacts were also asked if they were arrested during the contact. Regardless of responses in the use of 

force module, all respondents were then routed to a set of questions about the reason for their most 

recent contact with police. It is important to note here that if respondents reported more than one 

contact at the beginning of the interview, the instrument ended with a follow-up question about the use 

or threat of force in any earlier contacts.

The section on the reason for police contact (Exhibit 2.1) was used to determine which of the 

respondent’s types of contact over the past year would be asked about in detail. Each question asked 
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 9

about a particular type of contact with the police. These questions were asked until the respondent 

provided an affirmative response to one type of force, ultimately lending a bias associated with the 

types of contact and the order in which they were asked in the screener. Once a respondent answered 

one of these screener questions in the affirmative, the instrument routed the interview to a detailed 

module for the type of contact selected.

Exhibit 2.1 2008 instrument reasons for contact

# Types of Contact

1 Involved or witnessed a traffic accident

2 Driver in a traffic stop

3 Passenger in a traffic stop

4 Reported a crime or some other problem to police

5 Police were providing some sort of service or assistance

6 Police were investigating a crime

7 Police suspected respondent of something

8 Some other reason for contact

Finally, the respondents with face-to-face police contact answered detailed questions based on the 

most recent type of contact reported. The 2008 instrument collected more detailed information about 

traffic-related police-public contacts than other types of contact. Respondents who reported their most 

recent face-to-face contact with police was during a traffic stop while they were driving received 

additional questions on the reason for the traffic stop, characteristics of the stop, and outcomes of the 

stop, including receiving a warning, being ticketed, or experiencing vehicle or personal searches during

the stop. Respondents who reported any type of contact unrelated to being the driver in a traffic stop 

were immediately routed to a separate section on personal searches and other outcomes of police 

contact. Many of the items asked of persons with non-traffic stop contacts were also asked of persons 

who reported their most recent contact was as a passenger during a traffic stop. 

2.1.2 2011 instrument approach

The 2011 instrument consisted of three basic components:

1. Determining the types and total number of contacts that occurred in the past 12 months,

2. Determining the most recent contact, and

3. Detailed modules regarding the characteristics and outcome of the most recent contact, 

including use of force.

To obtain information about the types and total number of contacts in the past 12 months, the 2011 

instrument contained an extensive behaviorally specific screener that asked respondents whether they 

had experienced particular types of contact during the year (Exhibit 2.2), regardless of whether they

were in person or over the telephone. Additionally, respondents were asked to report the number of 

contacts during the 12-month period by types of contact, followed by a question about the number of 

face-to-face contacts. In the new instrument, respondents were able to select multiple types of contact 

in the screener section, including types of contact that were not necessarily face-to-face. If respondents
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 10

indicated having had no contact with police in the past 12 months, they would be routed to the end of

the instrument and the interview was ended.

If a respondent selected more than one type of contact in the screener section, he or she was asked 

to indicate the most recent contact. Depending on the type of contact or most recent contact reported, 

respondents were then routed into detailed modules. As in the prior instrument, respondents who 

experienced a traffic stop were asked questions specific to traffic stops. Additionally, those stopped on 

the street but not in a moving vehicle were asked a separate set of additional questions. 

Exhibit 2.2 2011 instrument reasons for contact

# Types of Contact 

1 Reported any kind of crime, disturbance, or suspicious activity to the police

2 Reported a non-crime emergency such as a traffic accident or medical emergency to the police

3 Participated in block watch or other anti-crime programs with police

4 Approached or sought help from the police in the last 12 months for something not mentioned 

(accompanied by an open-ended specification)

5 Stopped by police while in a public place but not a moving vehicle

6 Stopped by police while driving a motor vehicle

7 Been a passenger in a motor vehicle that was stopped by police

8 Been involved in a traffic accident that was reported to the police

9 Been arrested

10 Stopped or approached by police in the last 12 months for something not mentioned 

2.1.3 Additional differences between the 2011 and 2008 instruments

There were five notable differences between how the two instruments identified types of contacts.

The first and, perhaps, most important difference between questionnaires is that the 2008 instrument 

asked respondents to indicate whether or not they had a face-to-face contact with police in a singular 

questionnaire item without providing a comprehensive definition or example of face-to-face contact

with police. Conversely, the 2011 instrument asked respondents a series of behaviorally specific 

questions to determine whether or not a face-to-face contact occurred. The series of behaviorally

specific questionnaire items served as examples of contact with police, both allowing respondents to 

report multiple contacts with police and triggering improved recall of events.

The second major difference was that the 2011 instrument included measurement of two types of 

contact that were not measured in the 2008 questionnaire and two types of contact that were 

expanded upon in the redesigned questionnaire. The types of contact not measured in 2008 were 

participation in a block watch or other anti-crime programs with police and being stopped or 

approached by police in the last 12 months for something not mentioned. By including block watches

and anti-crime programs and an open definition of contact with the police in the 2011 instrument, the 

opportunities for respondents to remember and report a contact with police were expanded. Being 

involved or witnessing a traffic accident was expanded in 2011 by including two types of contacts: 

reporting a non-crime emergency such as a traffic accident or medical emergency to the police and

being involved in a traffic accident that was reported to the police. The 2008 questionnaire asked 

respondents about contact as a result of reporting only a crime or suspicious activity to the police, and
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 11

the 2011 refined this as reporting any kind of crime, disturbance, or suspicious activity to police. The 

2011 instrument introduced the concept of a street stop by asking respondents if they were stopped 

while in a public place, but not in a moving vehicle. This differed from the 2008 instrument where 

respondents were asked if contact was specifically a result of police providing service or assistance, 

investigating a crime, or suspecting the respondent of something. Though the inclusion of these

additional types of contact and expansion of some existing types of contact improved respondents’ 

recall, it also contributed to incomparability between the distributions for 2008 and 2011 for certain 

contact types. Moreover, the contact specific modules in the 2011 questionnaire collected more 

detailed information about the characteristics and outcomes of the contact, particularly for policeinitiated traffic and street stops (see Appendix Table 1 for a comparison of the two modules).

The third difference was that three of the types of contact measured in the 2008 instrument were 

moved in the 2011 instrument to the characteristics of street stop module. Respondents who were 

filtered into the street stop section of the 2011 instrument were asked if: (1) police suspected 

respondent of something, (2) police were investigating a crime, and (3) police were providing a service 

or assistance to the respondent (see Exhibit 2.1, Exhibit 2.2). In the 2008 instrument, these types of 

contact could have been considered respondents’ most recent type of contact. This is not possible with 

the 2011 instrument since these items were administered only to respondents who had indicated a 

street stop as their most recent or only contact with police in the 12 months preceding the interview.

Moving these questionnaire items to a section of the questionnaire received only by respondents 

reporting street stops prevents estimate comparability with previous survey iterations by altering the 

respondent domain to those respondents with a street stop in the past year. 

The fourth difference between the 2008 and the 2011 instruments was that in 2011, all respondents 

with any type of contact were eventually filtered to a module on police behaviors. This ensured that 

each respondent with any contact was asked about his or her perceptions of police behavior during the 

contact. These included such items as whether the respondent felt the police behaved properly and if 

they treated the respondent respectfully. 

The fifth difference is how the two instruments measured use or threat of force during the most 

recent contact with police. The 2008 instrument routed respondents through a specific section of useof-force questions early in the interview only if respondents affirmed they had experienced use or threat 

of force during their most recent contact with police in a leading gate question. The 2011 instrument

took a more accessible approach, including a set of behaviorally specific use or threat of force questions

that were asked of all respondents reporting a street stop or traffic stop as the most recent contact.

Eliminating the lead question about use or threat of force from the 2011 instrument was an effort to 

improve recall of events that might have occurred during respondents’ contact with police and thus 

improve the quality of the estimate of use or threat of force during contact. The fundamental difference 

between the measurement of use or threat of force in these questionnaires is that the redesigned 

instrument did not require respondents to affirm that they experienced an undefined use or threat of 

force in the form of a gate question before being asked the group of questions that provides 

behaviorally specific examples of force. The behaviorally specific force questions are almost identical to 

those found in the 2008 instrument with three additional types of force included in this group of 
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 12

questions: threaten to arrest, threaten to ticket, and handcuffs. In both the 2008 and 2011 instruments, 

all respondents who reported more than one contact in the screener section were asked about

experiencing use or threat of force during any contact in the past 12 months at the end of the 

instrument.

In the 2011 instrument, the use of force questions were asked only in the traffic and street stop 

modules. They were not asked in the voluntary contact module and thus not asked of respondents 

routed into this module based on the most recent contact. As these respondents indicated a voluntary 

contact with police and were less likely to experience use or threat of force during such a contact, they 

were not asked about force to minimize respondent burden. Respondents who reported an arrest as 

their most recent or only contact with the police also did not receive the use of force questions as these 

respondents were routed through the voluntary contact module. Therefore, an overall estimate on use 

or threat of force across all types of contact cannot be obtained with the 2011 instrument. 

2.2 Comparison of estimate types

As mentioned in Section 2, a revised questionnaire item must meet two criteria to be determined 

comparable with the previous instrument’s counterpart. The questionnaire item must: (1) measure the

same object or outcome of interest via similar or identical wording or expand upon the existing

measurement and (2) share the same respondent domain. A questionnaire item can exist in a revised 

instrument in the exact wording, formatting, or order as the original instrument, but without a 

consistent or reproducible respondent domain, it is impossible to compare the original estimate from 

the previous survey year to the new estimate.

As such, the qualitative review of a revised instrument to determine if the two criteria are met 

should examine question wording, placement, and skip patterns to determine if there is the potential 

for measurement error between the compared questionnaire items. When reviewing question wording, 

one should be cognizant of definitions or phrasing that may elicit a different interpretation by the 

respondent. If the question wording changes the entire meaning of the previous item, then it may not 

be possible for an adjustment to account for the measurement error. For question placement and skip 

patterns, one should determine what, if any, errors of commission or omission2 are possible. For 

example, if the new instrument alters the respondent universe for an item (i.e., the number of 

respondents eligible for the item changes) the extent to which the universe will change needs to be 

assessed. For outcomes that will produce rate or proportion estimates, a large change in the universe 

can greatly impact the estimate due to the change in the denominator of the estimate.

 2 Errors of commission occur when respondents receive questionnaire items they are ineligible for or not supposed 

to answer, and errors of omission occur when a respondent does not receive the questionnaire items he or she 

should answer (Kreuter, 2015).
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 13

The following sections detail how the following outcomes were determined to be eligible for trend 

continuation:

• Face-to-face contacts with police,

• Percent of residents for whom the most recent contact was as a driver in a traffic stop, as a 

passenger in a traffic stop, in a traffic accident, or because of reporting a crime or problem to 

police,

• Use or threat of force during most recent contact with police in the past 12 months,

• Arrest, and

• Public perceptions of police behavior during contact.

Because these estimates were found comparable between questionnaire iterations, it can be 

presumed that any statistical difference detected between the resulting estimates is a result of 

measurement error and requires adjustment for trend continuation. The estimates shown in Exhibit 2.3

are weighted to the U.S. population and are based on the split-sample used to conduct the 2011 PPCS.

The 2011 PPCS sample was split between the two questionnaire iterations discussed earlier, with 84% of 

the sample receiving the 2011 instrument and 16% of the sample receiving the 2008 instrument.

Standard errors for the estimates were generated using Generalized Variance Function (GVF) 

parameters produced by the Census Bureau. 

Exhibit 2.3 PPCS weighted split-sample estimates for measures of interest, 2008 and 2011 instruments

Estimate Type

Initial (2008) 

Instrument

Estimate

Revised (2011) 

Instrument Estimate

Face-to-face contact 19.1% 22.8%††

Use or threat of force during contact 2.5 4.1†

Arrested during contact 3.6 3.1

Driver in a traffic stop as most recent contact 7.0 9.0††

Passenger in a traffic stop as most recent 

contact 0.5 2.0††

Traffic accident as most recent contact 2.4 2.3

Reported crime or problem to the police as 

most recent contact 4.4 7.0††

Police behaved properly 89.7 91.2

See appendix table 2 for standard errors.

† Ratio significantly different from 1 at the 0.05 level.

†† Ratio significantly different from 1 at the 0.01 level.

2.2.1 Face-to-face contact

A key estimate from the PPCS is the proportion of people with face-to-face contacts with police 

during the past 12 months. The 2008 instrument instructed respondents to report on only face-to-face 

contact with police, whereas the 2011 instrument did not limit respondents on the types of contacts 

they could report. Face-to-face contact includes traffic-related contacts (stopped by police as a driver, 

stopped by police in a moving vehicle as a passenger, or being involved in a traffic accident), contact due 
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 14

to being stopped in a public place not in a moving vehicle or otherwise stopped or approached by police 

in some other context, voluntary contacts like participating in a block watch or other anti-crime 

programs with police, approaching the police for help or assistance, and being arrested. For types of 

contacts that could have occurred by phone or email or otherwise not face-to-face, such as reporting a 

crime or non-crime emergency to police, follow-up questions were asked to obtain information about 

the mode of contact and whether the contact was face-to-face. So while the 2011 instrument employed 

a more inclusive definition of police contact than the 2008 instrument, the 2011 instrument did allow 

for face-to-face contacts to be identified and distinguished from non-face-to-face contacts. Ultimately, 

the respective estimates for face-to-face contact for each instrument are comparable due to the shared 

respondent domain and question wording among the 2008 and 2011 instruments.

2.2.2 Most recent contact and contact types

Respondents who reported more than one police contact during the prior 12 months were asked to 

identify which contact had occurred most recently and focus on that contact when answering detailed 

follow-up questions about the nature and outcomes of police contact. Whether the respondent had only 

one contact or was focusing on the most recent contact, all were asked questions to classify the type of 

contact that occurred. For analytic purposes, respondents were later grouped according to the type of 

contact experienced during their most recent contact. One of the larger differences between the 2008 

and 2011 instruments was how each dealt with the concepts of most recent contact and contact type.

The differences between these concepts made it difficult to compare many estimates. Ultimately, the 

challenges to comparability for most recent contact and contact type can be summarized in three facets:

1. Structure of the questionnaire,

2. Differences in the types of contact defined, and 

3. Resulting differences in the distribution of those contact types.

As discussed in Section 2.1.1, the 2008 instrument asked respondents directly to answer the 

questionnaire with their most recent contact in mind if they had reported more than one face-to-face 

contact with the police in the year preceding the interview date. In contrast, the 2011 instrument asked 

respondents to select all the types of contact they had in the past year and then asked respondents to 

indicate their most recent contact out of all the types reported. The major resulting difference was that 

the 2011 instrument gave respondents the opportunity to recall and report multiple types of contact 

and then filtered respondents according to the most recent contact out of all those reported. It is also 

important to note that in addition to allowing only one type of contact to be selected, the 2008 

instrument privileged certain types of contact over others via the hierarchical skip pattern whereas the 

2011 instrument type of contact screener questions were asked exhaustively (see Section 2.1.2). Though 

the 2011 questionnaire expanded on the 2008 instrument and gathered more information, the 

difference in questionnaire structure rendered some estimates of contact incomparable across survey 

years since some types of contact were asked in a different section of the instrument.

The 2008 and 2011 instruments also differed in how they asked about non-traffic, police-initiated 

contact. The 2008 instrument allowed respondents to report that the most recent contact occurred 

because the police were investigating a crime or suspected them of something (see Exhibit 2.1). The 
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 15

2011 instrument did not have an analogous item listed as a type of contact. Instead, the 2011 

instrument screener included a seemingly broader type of contact option that asked whether the 

respondent had been stopped by police in a public place but not in a motor vehicle, also known as a 

street stop. If the respondent selected street stop as the most recent contact, he or she was then asked 

a series of follow-up questions about the nature of the contact, including whether it occurred because 

the police were investigating a crime or suspected them of something. However, contact with the police

because the police were investigating a crime or suspected the respondent of something may have 

occurred for reasons other than a street stop. The 2011 instrument was not designed to measure these 

reasons for any type of contact besides street stops.

The differences in questionnaire structure combined with inconsistent definitions of contact type 

created differences in the distributions of types of contact that made certain estimates incomparable. 

First, the 2011 instrument measured several types of contact that were not asked about in the 2008 

instrument: (1) reported a non-crime emergency such as a traffic accident or medical emergency to the 

police, (2) participated in block watch or other anti-crime programs with police, (3) stopped by police 

while in a public place but not a moving vehicle (street stop), and (4) stopped or approached by police in 

the last 12 months for something not mentioned. All of these types of contact were deemed 

incomparable since analogous information was not available from the 2008 instrument. Second, the 

2011 instrument measured some types of contact in a way that was incomparable to the measurement 

in the 2008 instrument for the same types of contact. This difference is also tied to questionnaire 

structure—for example, the 2008 instrument included some “reasons for contact” that the 2011 

instrument did not consider in the contact screener. Unfortunately, due to the difference in 

questionnaire structure, the following three reasons or types of contact were asked only of respondents 

reporting a street stop as the most recent or only contact with police in the 2011 instrument street stop 

module: (1) police suspected respondent of something, (2) police were investigating a crime, and (3) 

police were providing a service or assistance to the respondent. These estimates were not comparable 

between instruments since the 2011 instrument collected this information only from respondents who 

reported a street stop.

While the overall question of a person’s most recent type of contact was determined to be 

incomparable between the two instruments, the proportion of the population that experienced 

particular types of contact can still be compared. After reviewing each type of contact individually, 

taking into account the differences in the structure of the instrument, four types of contact are 

comparable across instruments: (1) driver in a traffic stop, (2) passenger in a traffic stop, (3) traffic 

accident, and (4) reporting a crime or problem to the police. See Exhibit 2.3 for the associated weighted 

split-sample estimates.
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 16

2.2.3 Use or threat of force

The PPCS can also be used to estimate the proportion of the population that experienced the threat 

or use of nonfatal force by police during a contact. Use or threat of force is a composite measure, 

created from the combination of multiple behaviorally specific questionnaire items asking respondents 

if they had experienced any of the described actions by police. This was a major focus of improvement in 

the 2011 instrument revisions, and the resulting split-sample estimates reflected this improvement with 

2.5% of respondents reporting use or threat of force in the 2008 instrument compared to 4.1% of 

respondents reporting use or threat of force in the 2011 instrument (Exhibit 2.3). At the beginning of 

the 2008 instrument, respondents were asked whether they had experienced the use or threat of force

during their most recent face-to-face contact with police in the past year with a singular questionnaire 

item. The phrase “use or threat of force” was not defined for respondents. If the respondent said “yes’”

to this question, he or she was then asked a series of questions about the type of force used and 

outcomes of the contact. The 2011 instrument asked respondents about force in different areas of the 

questionnaire, depending on type of most recent contact, in a series of behaviorally specific 

questionnaire items without a gate question. By eliminating the singular questionnaire item that 

required respondents to define use or threat of force themselves prior to receiving the behaviorally

specific use or threat of force questions, this approach was designed to improve recall of events that 

may have transpired that respondents may not have defined as use or threat of force, such as shouting 

or being threatened with a ticket. As such, the elimination of the gate question from the 2008 

questionnaire is likely to produce higher estimates of use or threat of force. 

The other major difference between the two questionnaires was in the content of the questions 

used to measure use or threat of force during a contact with the police. Both instruments contained the 

following nine response items for use or threat of force, grouped in the questionnaire: (1) shouting; (2) 

cursing; (3) threatening to use force; (4) actually pushed or grabbed; (5) actually kicked or hit; (6) 

actually sprayed with chemical or pepper spray; (7) actually used an electroshock weapon, such as a 

stun gun; (8) actually pointed a gun; and (9) used any other type of force. The 2011 instrument included 

three additional choices for the use or threat of force item: (1) threat of ticket, (2) threat of arrest, and 

(3) been handcuffed. These three additional response items included in 2011 were grouped with the 

other nine use or threat of force response items. In contrast, the 2008 instrument asked respondents if 

they had been handcuffed in a visually separate questionnaire item outside of the nine grouped use or 

threat of force response items.

Because of the difference in how force is captured in both instruments, multiple definitions were 

explored to determine which measurement would be the most comparable while still incorporating as 

much of the expanded behavioral force questions as possible. There were four different combinations of 

the aforementioned questionnaire items explored and summarized in Exhibit 2.4. The four 

measurement approaches noted by number are—

1. Combined all available force-related questionnaire items grouped in each instrument, 

eliminating handcuffs from the 2008 estimate; 

2. Excluded “threaten to arrest” and “threaten with a ticket/other tickets” from both estimates; 
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 17

3. Combined all available force-related questionnaire items grouped in each instrument, including

handcuffs in the 2008 estimate; and 

4. Excluded “threaten to arrest” and “threaten with a ticket/other tickets” and handcuffs from 

both estimates. 

These approaches are captured in the in Exhibit 2.4 with “x” denoting that the behavioral questionnaire 

item was included in that definition of force. The corresponding estimates are presented in Exhibit 2.5.

Exhibit 2.4 Use or threat of force items included in four measurement approaches by questionnaire 

Use or Threat of Force Questionnaire Item

Measurement Approach

2008 Instrumenta 2011 Instrument

1 2 3 4 1 2 3 4

Shout x x x x x x x x

Curse x x x x x x x x

Threaten to arrestb x x

Threaten with a ticket/other ticketsb x x

Threaten to use force x x x x x x x x

Actually push or grab x x x x x x x x

Handcuffc x x x x x

Actually kick or hit x x x x x x x x

Actually spray with chemical or pepper spray x x x x x x x x

Actually use an electroshock weapon, such as a stun gun x x x x x x x x

Actually point a gun x x x x x x x x

Use any other type of force x x x x x x x x

Experienced use or threat of force in an earlier 

 contact in the past 12 monthsd x x x x x x x x

a

Required affirmative response to leading gate question asking if respondent had experienced use or threat of force in 

most recent contact with police in past 12 months prior to asking the group of behaviorally specific force questions.

b

Item not available in 2008 instrument.

c

This questionnaire item was asked separately in 2008 and was included with the module of force items in 2011.

d

Found at the end of both questionnaires for respondents reporting more than one contact.

After examining the estimates associated with each approach from Exhibit 2.4 and shown in Exhibit 

2.5, it was first determined that the inclusion of the handcuff item was not a viable measurement option 

to include in the final estimate for the 2008 instrument, eliminating Approaches 2 and 3. Including the 

handcuff item in the 2008 estimate for Approaches 2 and 3 increased the estimate of respondents 

experiencing use or threat of force during contact from 2.5% to 5.7%. The 2008 instrument asked the 

handcuff item separately from the rest of the force items, which suggests this inflation was due to the 

questionnaire design. The overall estimate of force using the 2011 questionnaire including all available 

items is 4.1% and statistically different from the 2008 estimate excluding the handcuff item of 2.5%.

Since the 2011 measurement of Approach 1 includes handcuffs along with two additional use or threat 

of force items, the associated estimate (4.1%) is still less than that of the estimate associated with the 
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 18

2008 measurement of Approaches 2 and 3 including an additional handcuff item alone (5.7%). Since

both estimates were measured in the same year in the split-sample design, it is reasonable to suggest 

the inclusion of the handcuff item in the 2008 instrument measurement would not provide a statistically 

comparable estimate appropriate for continuing trend analysis with the 2011 instrument. The 2011 

estimate associated with Approach 4 (2.3%) measured use or threat of force without taking advantage 

of comparable additions of extra force items and was not significantly different from the 2008 

instrument estimate (2.5%).

Exhibit 2.5 Estimates associated with measurement approaches of use or threat of force outlined in 

Exhibit 2.4

Measurement 

Approach

Initial (2008) Instrument

Estimate

Revised (2011) 

Instrument Estimate Significance

1a 2.5% 4.1% †

2b 5.7% 2.7% ††

3c 5.7% 4.1% ‡

4d 2.5% 2.3%

‡ Difference in the 2008 questionnaire estimate and the 2011 questionnaire estimate are significant at the 0.10 

level.

† Difference in the 2008 questionnaire estimate and the 2011 questionnaire estimate are significant at the 0.05 

level.

††Difference in the 2008 questionnaire estimate and the 2011 questionnaire estimate are significant at the 0.01 

level. a

Combined all available force-related questionnaire items grouped in each instrument, eliminating handcuffs 

from the 2008 estimate.

b

Excluded “threaten to arrest” and “threaten with a ticket/other tickets” from both estimates. c

Combined all available force-related questionnaire items grouped in each instrument, including handcuffs in 

the 2008 estimate.

d

Excluded “threaten to arrest” and “threaten with a ticket/other tickets” and handcuffs from both estimates.

After careful consideration, it was determined that Approach 1 would provide the most valid 

comparable estimates by directly comparing two estimates measured from similarly grouped questions.

While the estimates are not as similar as Approach 4, Approach 1 is the preferable method of 

measurement because it both includes items similar to prior instrument items and takes advantage of 

the new questionnaire items. Though the 2011 estimate includes handcuffs, threatened with a ticket, 

and threatened to arrest, the inclusion of these items are an important improvement to the 

measurement of use or threat of force that do not prevent comparisons to the prior measure. However, 

the separate handcuff item is excluded from the new measurement because these questions were 

grouped in the instrument, and this approach also avoids potential context effect in the estimate. 

Though instrumentally comparable, the overall estimates of use or threat of force during a contact were 

significantly different between the split-sample groups at the 0.05 level (see Exhibit 2.5 and Appendix 

Table 5 in the Appendix for more details).

In the 2011 questionnaire, respondents who reported an arrest, an accident, a voluntary contact, or 

another contact not mentioned in the screener section as their most recent contact were not asked the 
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 19

use of force questions. Because of this, it was not possible to generate an overall estimate of the 

prevalence of police use of nonfatal force. This was a shortcoming of the 2011 instrument and means 

that use of force estimates could be compared only for respondents with specific types of police 

contact. 

2.2.4 Arrests

Among those with contacts with police in the past year, 2.9% of respondents receiving the 2008 

instrument reported being arrested during their most recent contact with the police in the past year,

and 3.1% of respondents receiving the 2011 instrument reported being arrested in the past year or 

during the most recent contact with police (Exhibit 2.3). This estimate excludes individuals without 

contacts with police in the past year3 as well as those who were arrested and subsequently incarcerated 

during the time of data collection. The 2008 and 2011 instruments diverged when measuring arrest 

among respondents. The major difference is the 2008 instrument treated arrest as a sub-element of a 

contact whereas the 2011 instrument considered arrest as both a sub-element and a type of contact. 

The 2008 instrument asked all respondents with at least one face-to-face contact if they were arrested 

during their most recent contact. In contrast to viewing arrest solely as an outcome of a contact, one of 

the screening questions in the 2011 instrument asked respondents if they had been arrested during the 

prior 12 months. The 2011 instrument also gave respondents who reported their most recent contact as 

a street stop or traffic stop a second opportunity to report being arrested as an outcome of the contact.

Out of all of the respondents indicating an arrest at some point in the 2011 questionnaire (n=261), very 

few respondents (n=15, 5.8%) indicated an arrest as an outcome of a traffic or street stop without also 

indicating an arrest as a type of contact. This inconsistency in response suggests some level of 

measurement error may remain in the PPCS estimate of arrest in the survey year.

Though the questionnaires measured arrest in different ways, the estimates of arrest for each year 

were determined to be comparable due to the consistency in respondent domain and similarity in 

resulting split-sample. The 2008 estimate of arrest used the singular questionnaire item that asked all

respondents reporting an in-person contact if they had been arrested during their most recent contact 

with the police. This was the only question in the 2008 instrument that asked respondents about arrest.

The 2011 estimate of arrest was derived from the screener question asked of all respondents and the 

two additional questions about arrest from the street and traffic stop modules, omitting the 

questionnaire items about being threatened with arrest by police. Considering there were so few 

respondents who did not indicate an arrest as a type of contact, this definition was both inclusive of all 

respondents indicating an arrest in the 2011 instrument and comparable to the 2008 estimate by 

expanding the respondent domain and maintaining the same wording of the question.

 3

Data from the 2002 Survey of Inmates in Local Jails indicate a very small percentage of inmates reported being 

arrested without any police contact; however, for this report the percentage is negligible and will be ignored. 
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 20

2.2.5 Police behaved properly during contact

The questions about public perception that police behaved properly during the most recent or only 

contact were largely comparable between the 2008 and 2011 instruments. The majority of split-sample 

respondents with a face-to-face contact reported police behaving properly during contact with 89.7% in 

the 2008 instrument and 92.1% in the 2011 instrument (Exhibit 2.3). Both the 2008 and 2011

instruments asked all respondents with a face-to-face police contact about whether police behaved 

properly or improperly. Because the instruments asked nearly the same item of all respondents with 

contact, the estimates were comparable. However, this does not mean that an adjustment is not 

necessary. It is possible that changes to the PPCS screener from 2008 to 2011 could have resulted in a 

different composition of respondents with different types of force, which could in turn affect the 

proportion who believed the police behaved properly and respectfully. 

3. Methods of Adjustment

After reviewing the key outcome types and determining which were comparable over time, an 

analysis was conducted to determine the proper adjustment approach and the appropriate level for the 

adjustment.

3.1 Methods for comparing estimates from two instruments

3.1.1 Comparing estimates between the two instruments

Given the structural and definitional differences in the two instruments described in Section 2, it is 

necessary to quantify the magnitude that these differences have on estimates. To assess these 

differences, one cannot simply compare the estimates from the 2011 PPCS survey to those of the 2008 

PPCS survey since differences could be attributed to changes to the instrument, changes over time, or 

both. To control for time, the U.S. Census Bureau implemented a split-sample design in 2011 in which 

19% (11,833) of respondents were randomly assigned to receive the 2008 instrument and the remaining 

81% (50,447) of respondents were to receive the 2011 instrument. However with non-response taken 

into account the actual split-sample allocation was 16% (7,838) of respondents receiving the 2008 

instrument and the remaining 84% (41,408) respondents receiving the 2011 instrument.

Using this split-sample design, any differences in the estimates are due entirely to differences in the 

instrument, as there were no major differences in response rates or nonresponse bias between the 

2008 and 2011 instruments. These measurement differences can be identified and methods developed 

to adjust estimates in prior survey years to account for the measurement differences and allow for the 

examination of true change over time. 

3.1.2 Options for using a split-sample to adjust data

The adjustment produced to correct for any changes due to measurement differences in the two 

instruments will depend on two key factors. First, the qualitative assessment of whether the estimates 

between the two instruments require an adjustment to account for measurement differences. Second, 

the sample size of the split-sample will impact the power by which more refined adjustments can be 

made. 
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 21

For estimates where measurement differences are suspected but the underlying construct is the 

same, two broad types of adjustment factors can be produced: (1) ratio adjustment and (2) model-based 

adjustment. The ratio adjustment consists of the ratio of the estimate from the new instrument over the 

corresponding estimate from the old instrument. This ratio can be based on all cases or conditioned on a 

set of characteristics such as gender or race/Hispanic origin. The ratio adjustment can be produced with 

relatively few cases; however, conditioning by a characteristic may require larger sample sizes if some 

subgroups are small or rare. Under the model-based approach, a logistic model is fit where the 

dependent variable is an indicator for the construct of interest (e.g., face-to-face contact) and the 

independent variables are indicators for the instrument year, demographic characteristics, and 

interactions between the instrument year and the demographic characteristics. By taking into account 

multiple demographic characteristics, the model-based approach produces an adjustment factor that is 

specific to the set of characteristics of the respondent. The model-based approach allows for a more 

accurate adjustment at the sub-domain level, but requires a larger sample size, which may not be 

feasible to obtain in a split-sample study. 

After analyzing the constructs for which measurement differences were a possibility (see Appendix

Table 1), it was determined that the sample size of the split-sample study did not support the modelbased adjustment or a conditional ratio adjustment. Therefore, as discussed in the next section, an 

overall ratio adjustment was implemented. 

3.1.3 Method used for adjusting estimates in prior survey years

Continuing trend analysis across PPCS cycles after an instrumentation change is analogous to 

comparing National Crime Survey (NCS) and NCVS estimates after the major redesign in 1992. As with 

the PPCS, the NCVS implemented a split-sample design during the transition year to assess the 

magnitude by which the redesigned NCVS instrument increased victimization rates for each crime type.

To account for the measurement differences between the NCVS and NCS, Lynch and Cantor (2005) 

developed a ratio adjustment by which the NCS victimization rate (X) for crime type j is adjusted as 

follows:

XXNNNNNNjj

AA = XXNNNNNNjj × RRjj

Where RRjj is the ratio adjustment based on the 1992 split-sample for crime type j, which is defined as

RRjj = �

XXNNNNNNNNjj

XXNNNNNNjj

iiii

XXNNNNNNNNjj

XXNNNNNNjj

ss ssss ssssssssssss dd dddddd ffff 1

1 OO h ee

Where XXiijj i = NCS or NCVS is the estimated victimization rate from the split-sample for crime type j. 

Lynch and Cantor (2005) then adjusted the standard errors assuming the ratio adjustment is a fixed 

constant
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 22

SSSS �XXNNNNNNjj

′ � = SSSS �XXNNNNNNjj� × RRjj

Given the PPCS is a supplement of the NCVS, to be consistent, it was determined that the Lynch and 

Cantor (2005) adjustment method was the most appropriate. However, for the PPCS, the adjustment is 

made for each type of contact where for a given type of contact c, the ratio adjustment is defined as

RRcc = �

XX2011cc

XX2008cc

iiii

XX2011

XX2008cc

ss ssssssssssssss dd dddddd ffff 1

1 OO h ee

And, the resulting adjusted estimate is calculated as

XXYYYYYYYYcc

AA = XXYYYYYYYYcc × RRcc

Where YYYY represents the survey year prior to 2011 being estimated (i.e., 2002, 2005, or 2008).

Following the Lynch and Cantor approach, the standard errors for each type of contact in a given year 

were also adjusted with the ratio adjustment as a fixed constant. While this approach may inflate the 

standard errors, other options are also problematic given the limited number of sample cases in the 16%

split. 

As discussed in Section 2, understanding the differences between the 2008 and 2011 instruments is 

integral to evaluating estimate comparability. There is consistency over time across a number of PPCS 

questionnaire items, necessitating an adjustment factor to account for instrument and item revisions

and to support trend continuation. 

3.2 Determining appropriate level for adjustment

As noted earlier, the ratio adjustment to account for differences in the estimates due to the 

instrument change is applied only when the split-sample indicates that the ratio is significantly different 

from one. Exhibit 3.1 presents the PPCS estimates that are based on the split-sample and the resulting 

ratio adjustments. For most comparable estimates, the difference in adjustment ratios were significantly 

different from one. The exceptions were the percent of those with contact who were arrested, the 

percent of those who experienced a traffic accident as the most recent contact, and the percent who 

believed the police behaved properly during the contact. For the estimates in which the 2011 estimate is 

significantly different from 2008, the ratio adjustment showed that the revised PPCS instrument elicited 

higher percentages than the prior instrument. This suggests the 2011 instrument revisions improved 

respondents’ recall of contact with police.
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 23

Exhibit 3.1 Estimates by type of contact based on the PPCS split-sample and resulting ratio adjustment 

Estimate Type

Initial (2008) 

Instrument

Estimate

Revised (2011) 

Instrument

Estimate

Ratio

(2011/2008)

Ratio 

Adjustment 

Face-to-face contact 19.1% 22.8%†† 1.2†† 1.2

Use or threat of force during 

contact 2.5 4.1† 1.6† 1.6

Arrested during contact 3.6 3.1 0.9 1.0

Driver in a traffic stop as most 

recent contact 7.0 9.0†† 1.3†† 1.3

Passenger in a traffic stop as 

most recent contact 0.5 2.0†† 4.2†† 4.2

Traffic accident as most recent 

contact 2.4 2.3 1.0 1.0

Reported crime or problem to 

the police as most recent 

contact

4.4 7.0†† 1.6†† 1.6

Police behaved properly 89.7 91.2 1.0 1.0

See appendix table 2 for standard errors.

†Ratio significantly different from 1 at the 0.05 level.

††Ratio significantly different from 1 at the 0.01 level.

Appendix Tables 3 to 6 show the adjustment factors when conditioned on sex, age, and 

race/Hispanic origin. As the tables show, the sample sizes did not always allow for detectable 

differences to be found. Because of the sample sizes at the sub-domain level, it could not be determined 

if this was because there was no difference or because the comparison was under-powered. Due to this 

uncertainty, the sub-domain level adjustment factors were not used. 

4. PPCS Rates Over Time

4.1 Estimates for which trends can be examined

For the eight estimates discussed in Section 2, trends from 2002 to 2011 could be examined due to 

the general comparability of these measures over time. However, as previously discussed, most of those 

estimates were significantly different between the split-sample groups, so adjustment factors were 

applied to previous survey years’ estimates for comparability. As described in Section 3.1.1, each 

adjustment factor was applied to all previous survey years and thus the general direction of each trend 

line during the 6-year period remained unchanged.

In this section, the rates over time, both adjusted and unadjusted, are presented for the eight key 

estimates that were measured comparably over time.

4.1.1 Face-to-face contact

To account for the impact of changes to the instrument in 2011, an adjustment factor of 1.2 was 

applied to the 2002, 2005, and 2008 estimates of the percent of the population with one or more faceto-face contacts with police. If the 2011 instrument had been used in the prior PPCS survey years, the 
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 24

percentage of the population that had face-to-face contact with police would have been higher: 25.1% 

compared to 21.0% in 2002; 22.8% compared to 19.1% in 2005; and 20.2% compared to 16.9% in 2008.

Moreover, Figure 4.1.1 shows that the adjustment prevents erroneous between-year comparisons; 

there is no statistical difference between the 2008 estimate of face-to-face contact (20.2%) and the 

2011 estimate (22.7%). Appendix Table 3 presents the differences in estimates due to the instrument 

change by sex, age, and race/Hispanic origin. 

Figure 4.1.1 Adjusted and unadjusted rates for face-to-face contact, 2002–2011

Note: See appendix table 7 for estimates and standard errors. 
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 25

4.1.2 Driver in a traffic stop as most recent contact

The percentage of persons age 16 or older who reported that they were the driver in a traffic stop

during the most recent or only contact was significantly different between the split-sample groups. 

Therefore, an adjustment factor of 1.3 (see Exhibit 3.1) was applied to the 2002, 2005, and 2008 

estimates. The result of this adjustment is an increase in the percent of persons who were stopped as 

the driver in a traffic stop. The percentages increase from 7.8% to 10.0% in 2002, 7.8% to 10.0% in 2005, 

and 7.5% to 9.6% in 2008 (Figure 4.1.2). The standard error bars associated with the adjusted 2008 

estimate (9.6%) and 2011 estimate (9.0%) overlap, suggesting there is not a statistically significant 

difference between the two. Had the ratio adjustment not been applied, a significant difference would 

have been detected between the 2008 and 2011 estimates.

Figure 4.1.2 Adjusted and unadjusted rates for driver in a traffic stop, 2002–2011

Note: See appendix table 8 for estimates and standard errors.

4.1.3 Passenger in a traffic stop as most recent contact

The overall estimate of the percentage of people whose most recent contact with police was as a 

passenger in a traffic stop was significantly different between the split-sample instrument groups. An 

adjustment factor of 4.2 was applied to the previous survey years’ estimates, showing that had the 2011 

instrument been used, the percentage of the population reporting their most recent contact with police 

as being a passenger in a traffic stop would have increased. The percentage of the population whose 

most recent contact was as a passenger in a traffic stop increased from 0.6% to 2.4% in 2002; 0.6% to 

2.3% in 2005; and 0.5% to 2.0% in 2008 (Figure 4.1.3). Without the applied adjustment, the standard 
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 26

error bars would not overlap and lead to the incorrect conclusion that there was a significant change in 

the percentage of people whose most recent contact with police was as a passenger in a traffic stop 

between 2008 (0.5%) and 2011 (2.0%).

The estimates associated with passenger in a traffic stop as the most recent contact with police 

showed the largest difference in the split-sample estimates. As seen in Exhibit 3.1, the adjustment factor 

for passenger in a traffic stop is more than twice the size of the next largest adjustment factor (4.2

compared to 1.6 for use or threat of force). This suggests that the changes to the instrument had a 

larger effect on the estimate than other contact types. The larger change in the percentage of the 

population reporting their most recent contact with the police as a passenger in a traffic stop between 

2008 and 2011 may indicate that the 2008 and prior estimates were underreported. The revised 

screener served to effectively trigger better recall of this type of contact. 

Figure 4.1.3 Adjusted and unadjusted rates for passenger in a traffic stop, 2002–2011

Note: See appendix table 9 for estimates and standard errors. 
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 27

4.1.4 Traffic accident as most recent contact

There was no significant difference in the 2008 and 2011 split-sample comparison of the percent of 

persons who experienced a traffic accident as the most recent contact with police. Therefore, no 

adjustment was needed in the analysis of trends from 2002 to 2011, and the adjusted and unadjusted 

lines are identical (see Figure 4.1.4). This leads to estimates of 2.7% in 2002, 2.4% in 2005, 2.1% in 2008, 

and 2.3% in 2011. The PPCS data suggest that the percentage of people with traffic accidents as their 

most recent contact with the police remained stable over the years.

Figure 4.1.4 Adjusted and unadjusted rates for traffic accident, 2002–2011

Note: See appendix table 10 for estimates and standard errors. 
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 28

4.1.5 Reported crime or problem to police as most recent contact

Due to the significant difference in the overall estimates for the population of individuals whose

most recent contact with police was while reporting a crime or some other problem, an adjustment 

factor of 1.6 was applied to the previous survey year estimates (see Exhibit 3.1). This means that if the 

2011 instrument had been used in previous survey years, the percentage of the population whose most 

recent contact with police was reporting a crime or problem would have been higher (5.6% unadjusted 

compared to 8.7% adjusted in 2002, 4.5% unadjusted compared to 7.1% adjusted in 2005, and 2.8% 

unadjusted compared to 4.4% adjusted in 2008). Even after the adjustment was applied, the 2011 

percentage (7.0%) is greater than 2008 (4.4%), representing a reversal of the previous declines from

2002 and 2008 (see Figure 4.1.5). After accounting for changes to the survey instrument, the percent of 

persons age 16 or older whose most recent or only contact with police in the past year was reporting a 

crime or problem in 2011 was similar to what it had been in 2002. The 95% confidence interval 

associated with the 2008 adjusted estimate is (5.0, 5.8) and the 95% confidence interval associated with 

the 2011 adjusted estimate is (6.4, 7.6).

Figure 4.1.5 Adjusted and unadjusted rates for reported crime or problem to police, 2002–2011

Note: See appendix table 11 for estimates and standard errors. 
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 29

4.1.6 Use or threat of force

Figure 4.1.6 shows the adjusted and unadjusted trend lines for the use or threat of force that 

persons experienced during their most recent police contact. The overall estimate of use or threat of 

force the population experienced during their most recent contact was significantly different between 

the split-sample instrument groups, and an adjustment factor of 1.6 was applied to the 2002, 2005, and 

2008 survey year estimates (see Exhibit 3.1). After applying the adjustment factor, the results showed 

that had the 2011 instrument been used in prior survey years, the percentage of the population that 

experienced the use or threat of force during a police contact would have been higher overall (1.5%, 

2.3%, and 1.9% unadjusted compared to 2.4%, 3.8%, and 3.2% adjusted for respective survey years, see 

Figure 4.1.6).

Another important finding as result of the adjustment is that 2011 has similar rates of use or threat 

of force as prior survey years. These findings also indicate that previous instruments suppressed 

estimates of use or threat of force during respondents’ most recent contact or any other contact in the 

past year. However, despite the perceived increase when no adjustment is applied, the application of 

the adjustment factor shows that these differences are not statistically significant. If the adjustment 

ratio had not been applied, the standard errors associated with the 2008 estimate (1.9%, unadjusted) 

would not overlap with those associated with the 2011 estimate (4.1%), erroneously suggesting that 

there was a statistically significant difference between the 2008 and 2011 survey year estimates.

Figure 4.1.6 Adjusted and unadjusted rates for use or threat of force, 2002–2011

Note: See appendix table 12 for estimates and standard errors. 
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 30

4.1.7 Arrest during contact

There was no significant difference in the 2008 and 2011 split-sample comparison of the percent of 

persons who experienced an arrest as the most recent contact with police. Therefore, no adjustment 

was needed in the analysis of trends from 2002 to 2011, and the adjusted and unadjusted lines are 

identical (see Figure 4.1.7). This leads to estimates of 2.9% in 2002, 2.9% in 2005, 2.9% in 2008, and 

3.1% in 2011. The PPCS data suggest that the percentage of people reporting arrest during their most 

recent contact with the police stayed stable over the years.

Figure 4.1.7 Adjusted and unadjusted rates for arrest, 2002–2011

Note: See appendix table 13 for estimates and standard errors. 
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 31

4.1.8 Police behaved properly 

Using the split-sample in 2011, it was determined that changes to the instrument did not have a 

significant impact on the percentage of persons with contact who believed that that police behaved 

properly during contacts. Since there was no significant difference between the split-sample estimates, 

an adjustment factor of 1.0 is used when comparing the 2011 estimates to prior survey years (see 

Exhibit 3.1). Thus, the adjusted and unadjusted lines are identical. In 2002 and 2005, the percentage of 

people who had contacts with the police who believed the police behaved properly during the contact 

was above 90%, and the percentage in 2011 was 91.2%. This estimate dipped below 90% to 88.8% in the 

2008 survey year—although none of these estimates are statistically different across time (see Figure 

4.1.8).

Figure 4.1.8 Adjusted and unadjusted rates for police behaved properly, 2002–2011

Note: See appendix table 14 for estimates and standard errors.

4.2 Estimates for which trends cannot be continued

While many important outcomes from the PPCS can be trended with the assistance of an 

adjustment, as noted in Section 2, there are some that cannot. In these cases, the rates over time need 

to be interpreted with caution. 

4.2.1 Impact—break in series; how to interpret the estimates

When an adjustment cannot be used to correct for differences in measurement across instruments, 

there is a break in the series of estimates. In these cases, it is probably best not to compare estimates 

across time due to unintended changes. If discussions of change are necessary, it must be noted that 
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 32

any apparent shift over time could be attributed to methodological changes rather than true temporal 

changes.

It is recommended that the following outcomes not be compared over time due to a break in series

from the estimates available prior to 2011:

• The overall distribution of most recent contact and the following types of contact: (1) police 

suspected respondent of something, (2) police were investigating a crime, and (3) police were 

providing a service or assistance to the respondent; and

• The characteristics and outcome estimates associated with all types of contact except for drivers 

in a traffic stop.

The following two sections (4.2.2 and 4.2.3) explain why these estimates should not be evaluated over 

time. 

4.2.2 Most recent contact distribution

As described in Section 2.2, several contact types in the 2008 screener were moved into the street 

stop section of the 2011 instrument: police assistance, police investigating a crime, or police suspected 

respondent of wrongdoing. Therefore, these types of contacts are only asked of those who were routed 

into the street stop module (see Exhibit 4.2.1) rather than of all respondents as in 2008. The result of 

this instrument change is a suppression of respondents indicating this type of contact. For this reason, 

the 2011 distribution cannot be compared to prior survey years. Therefore, when examining trend, only 

the distributions between 2002 and 2008 can be compared, and the distributions for 2011 can only be 

compared with future iterations of the survey. 

Exhibit 4.2.1 Distribution of most recent contact among split-sample respondents by instrument

2008 Instrument 2011 Instrument

Traffic-related contacts

Driver during traffic stop 37.8% 40.2%

Passenger during traffic stop 2.5 8.8

Traffic accident 12.8 9.7

Other contacts

Reported crime/problem to police 23.9% 26.7%

Police provided assistance or service 8.1 2.5

Police investigating crime 5.4 0.5

Police suspected resident of wrongdoing 4.1 0.8

Other reasona 5.2 10.8 a

Includes a small percentage of cases in which the reason for contact was unknown.

4.2.3 Characteristics and outcome estimates for all types of contact except drivers in a traffic 

stop

As described in Section 2.1, the 2008 instrument filtered respondents into more detailed 

questionnaire modules to collect information regarding various characteristics and outcomes of the 

reported contact with police. Respondents were routed according to their reported most recent contact, 

and many of the detailed characteristic and outcome measures were included in the revised instrument.

Characteristics and outcomes of police-public contacts include but are not limited to personal or vehicle 
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 33

searches and enforcement actions like tickets or warnings. Though the revised questionnaire also 

filtered respondents into detailed modules based on the reported most recent contact, the 

incomparability of the distributions of most recent contact type resulted in an incomparability between 

the associated characteristic and outcome measures. Because of this, the same groups of respondents 

answered different characteristics and outcome measures depending on the version of the instrument 

received. For this reason, most of the 2011 measures associated with characteristics and outcomes of 

contacts cannot be compared to past survey years.

However, the characteristics and outcome measures associated with respondents reporting their 

most recent contact with police as a driver in a traffic stop were found to be mostly comparable since 

both instruments routed these respondents to analogous questionnaire modules. Since both 

instruments collected much of the same information from the same group of respondents, the trends 

associated with these outcomes and characteristics for drivers in a traffic stop can be continued in the 

2011 survey year for those estimates measured in previous survey years.
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 34

5. References

Cantor, D., and Lynch, J. P. (2005). Exploring the effects of changes in design on the analytical uses of the 

NCVS data. Journal of Quantitative Criminology, 21(3), 293-319. 

Clark, C. Z. F., Tinari, R., Singh, R., Tupek, A., Hogan, H., Killion, R. A., and Wright, T. (2003, July 25). Census 

Bureau Standard: Pretesting Questionnaires and Related Materials for Surveys and Censuses. 

Retrieved from https://www.census.gov/srd/pretest-standards.html.

Duncan, G., and Kalton, G. (1987). Issues of design and analysis of surveys across time. International 

Statistical Review, 55(1): 97-117.

Firebaugh, G. (1997). Analyzing Repeated Surveys. Sage University Paper Series on Quantitative

Applications in the Social Sciences, no. 07-115. Thousand Oaks, CA: Sage.

Kreuter, Frauke. (2015). Week 9: Questionnaire Design Slides. Personal collection of Frauke Kreuter, 

University of Mannheim, Mannheim, Germany.

Police-Public Contact Survey: A Supplement to the NCVS. (2011). Bureau of Justice Statistics.

Police-Public Contact Survey: A Supplement to the NCVS. (2008). Bureau of Justice Statistics.
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 35

6. Appendix

Appendix Table 1. PPCS constructs of interest and comparability categorization

Construct of Interest Comparability

Face-to-face contact with police in the past 12 months Similarly measured, adjustment needed

Number of face-to-face contacts in the past 12 months Similarly measured, not examined

Most recent contact with police in the past 12 months Incomparably measured

Contact occurred as a driver in a traffic stop Similarly measured, adjustment needed

Contact occurred as a passenger in a traffic stop Similarly measured, adjustment needed

Contact occurred due to involvement in a traffic 

accident reported to police

Similarly measured, adjustment not needed

Contact occurred due to reporting a crime to the 

police

Similarly measured, adjustment needed

Contact occurred because police were providing some 

sort of service or assistance

Incomparably measured

Contact occurred because police were investigating a 

crime

Incomparably measured

Contact occurred because police suspected 

respondent of something

Incomparably measured

Reasons for traffic stop Incomparably measured

Reasons for street stop Incomparably measured

Arrest during most recent contact Similarly measured, adjustment not needed

Use or threat of force during most recent contact Similarly measured, adjustment needed

Use or threat of force during prior 12 months Similarly measured, not examined

Perception of excessive force Similarly measured, not examined

Injury as a result of force used during contact Incomparably measured

Respondent actions during contact Incomparably measured

Respondent filed complaint as a result of contact Similarly measured, not examined

Number of officers present during contact Similarly measured, not examined

Race of officer(s) present during contact Incomparably measured

Time of day or night contact occurred Similarly measured, not examined

Length of contact Similarly measured, not examined

Location of contact relative to respondent’s home Incomparably measured

Presence of other people with respondent during 

contact

Incomparably measured

Vehicle and personal searches during contact Similarly measured, not examined

Perception of police action legitimacy during contact Similarly measured, not examined

Ticket or warning (verbal or written) received during 

contact

Incomparably measured

Police officer asked respondent to exit vehicle Incomparably measured

Perception of police behaving properly during contact Similarly measured, adjustment not needed

Perception of police treating respondent respectfully 

during contact

Similarly measured, adjustment not needed

Similarly measured, adjustment needed: Survey items are measuring the same underlying construct but differ in 

a way that affects the resulting estimates.

Similarly measured, adjustment not needed: Survey items are measuring the same construct and the manner of 

measurement did not change.

Similarly measured, not examined: Survey items are measuring the same underlying construct, but were not 

examined in this report.

Incomparably measured: Survey items were measuring fundamentally different constructs.
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 36

Appendix Table 2. Standard errors for Exhibits 2.3 and 3.1. Estimates by type of contact 

based on the PPCS split-sample and resulting ratio adjustment

Estimate Type

Initial (2008) 

Instrument 

Estimate SE

Revised (2011) 

Instrument 

Estimate SE

Face-to-face contact 1.40% 0.60%

Use or threat of force during contact 0.60 0.40

Arrested during contact 0.27 0.30

Driver in a traffic stop as most recent 

contact 0.74 0.36

Passenger in a traffic stop as most recent 

contact 0.12 0.14

Traffic accident as most recent contact 0.36 0.15

Reported crime or problem to the police 

as most recent contact 0.55 0.31

Police behaved properly 2.00 0.70
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 37

Appendix Table 3. Respondents with face-to-face contact with police, by questionnaire and 

demographic characteristics, 2011

Initial (2008) Questionnaire Revised (2011) Questionnaire

Number Percent Number Percent

Overall 46,506,800 19.1% 54,922,500 22.8%††

Sex

Male 22,683,100 19.5% 28,653,500 24.2%††

Female 23,823,700 18.8 26,269,000 21.3‡

Race

Whitea 33,758,000 20.4% 39,056,100 23.3%†

Black/African Americana 5,408,700 17.7 6,558,900 23.6†

Hispanic/Latino 5,104,500 16.4 6,091,500 19.5

Othera,b 1,624,000 12.0 2,313,300 18.5††

Two or more races 611,600 24.8 902,700 35.7‡

Age

16–17 1,027,000 11.8% 1,338,900 16.6%‡

18–24 8,887,600 27.7 9,294,800 32.3‡

25–34 10,719,700 25.0 11,543,100 27.6

35–44 7,907,700 20.3 10,096,300 24.8†

45–54 8,221,700 18.5 9,996,100 22.5†

55–64 6,117,400 17.1 7,289,800 19.3

65 or older 3,625,700 9.0 5,363,600 13.4††

See appendix table 15 for standard errors.

‡ Difference in the 2008 questionnaire estimate and the 2011 questionnaire estimate are significant at the 0.10 level.

† Difference in the 2008 questionnaire estimate and the 2011 questionnaire estimate are significant at the 0.05 level.

†† Difference in the 2008 questionnaire estimate and the 2011 questionnaire estimate are significant at the 0.01 level.

a

Excludes persons of Hispanic origin.

b Includes American Indian and Alaska Natives; Asian, Native Hawaiian, and Other Pacific Islanders.
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 38

Appendix Table 4. Respondents who experienced arrest during their most recent contact 

with police, by questionnaire and demographic characteristics, 2011

Initial (2008) Questionnaire Revised (2011) Questionnaire

Number Percent Number Percent

Overall 1,686,300 3.6% 1,710,300 3.1%

Sex

Male 1,160,800 5.12% 1,200,300 4.19%

Female 525,500 2.21 510,000 1.94

Race

Whitea 1,037,000 3.07% 899,200 2.30%

Black/African Americana 435,700 8.06! 383,100 5.84

Hispanic/Latino 213,500 4.18! 321,100 5.27

Othera,b -- -- 82,100 3.55

Two or more races -- -- 24,700 2.74!

Age

16–17 -- -- 30,700 2.29%!

18–24 377,200 4.24%! 576,300 6.20

25–34 714,100 6.66 513,100 4.44

35–44 296,500 3.75 259,000 2.57

45–54 236,000 2.87! 178,800 1.79

55–64 62,500 1.02! 115,800 1.59

65 or older -- -- 36,700 0.68

See appendix table 16 for standard errors.

‡ Difference in the 2008 questionnaire estimate and the 2011 questionnaire estimate are significant at the 0.10 level.

†† Difference in the 2008 questionnaire estimate and the 2011 questionnaire estimate are significant at the 0.01 level.

! Interpret with caution; estimate based on 10 or fewer sample cases or coefficient of variation is greater than 50%.

-- Number rounds to less than 0.5 a

Excludes persons of Hispanic origin.

b Includes American Indian and Alaska Natives; Asian, Native Hawaiian, and Other Pacific Islanders.
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 39

Appendix Table 5. Respondents who experienced use or threat of force during the most recent 

contact, by questionnaire and demographic characteristics, 2011

Initial (2008) Questionnaire Revised (2011) Questionnaire

Number Percent Number Percent

Overall 1,176,000 2.5% 2,277,300 4.1%†

Sex

Male 756,200 3.3% 1,490,800 5.2%†

Female 419,800 1.8 786,500 3.0†

Race

Whitea 753,200 2.2% 1,318,800 3.4%‡

Black/African Americana 233,800 4.3! 424,000 6.5

Hispanic/Latino 127,800 2.5! 440,100 7.2††

Othera,b 20,500 1.3! 57,000 2.5!

Two or more races 40,600 6.6! 37,400 4.1!

Age

16–17 -- --! 74,200 5.5%!

18–24 283,600 3.2%! 745,300 8.0††

25–34 427,700 4.0 612,400 5.3

35–44 171,000 2.2! 327,900 3.2

45–54 181,800 2.2! 270,000 2.7

55–64 111,900 1.8! 140,700 1.9

65 or older -- --! 106,900 2.0

See appendix table 17 for standard errors.

‡ Difference in the 2008 questionnaire estimate and the 2011 questionnaire estimate are significant at the 0.10 level.

† Difference in the 2008 questionnaire estimate and the 2011 questionnaire estimate are significant at the 0.05 level.

†† Difference in the 2008 questionnaire estimate and the 2011 questionnaire estimate are significant at the 0.01 level.

! Interpret with caution; estimate based on 10 or fewer sample cases or coefficient of variation is greater than 50%.

-- Number rounds to less than 0.5.

a

Excludes persons of Hispanic origin.

b

Includes American Indian and Alaska Natives; Asian, Native Hawaiian, and Other Pacific Islanders.
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 40

Appendix Table 6. Respondents with perceptions that police behaved properly during the most 

recent contact, by questionnaire and demographic characteristics, 2011

Initial (2008) Questionnaire Revised (2011) Questionnaire

Number Percent Number Percent

Overall 41,166,700 89.7% 54,138,600 91.2%

Sex

Male 19,679,800 87.9% 27,448,200 90.6%

Female 21,486,900 91.3 26,690,300 91.8

Race

Whitea 30,346,400 91.0% 39,468,200 92.2%

Black/African Americana 4,462,100 83.6 5,756,800 86.8

Hispanic/Latino 4,523,100 89.9 5,853,100 89.3

Othera,b 1,420,200 87.5 2,207,900 91.5

Two or more races 414,900 73.1 852,700 91.3‡

Age

16–17 1,005,100 97.9% 1,197,400 86.8%††

18–24 7,917,500 89.6 8,469,900 89.8

25–34 9,269,600 87.3 11,341,800 90.0

35–44 7,000,600 89.7 10,265,000 91.5

45–54 7,195,000 89.5 9,977,300 91.5

55–64 5,433,900 90.3 7,413,300 92.3

65 or older 3,345,000 93.7 5,473,900 94.5

See appendix table 18 for standard errors.

‡ Difference in the 2008 questionnaire estimate and the 2011 questionnaire estimate are significant at the 0.10 level.

† Difference in the 2008 questionnaire estimate and the 2011 questionnaire estimate are significant at the 0.05 level.

a

Excludes persons of Hispanic origin. b

Includes American Indian and Alaska Natives; Asian, Native Hawaiian, and Other Pacific Islanders.
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 41

Appendix Table 7. Standard errors for Figure 4.1.1. Adjusted and unadjusted rates for faceto-face contact, 2002–2011

Unadjusted Adjusted

Year Percent SE Percent Percent SE Percent

2002 21.01% 0.34% 25.08% 0.37%

2005 19.09 0.47 22.79 0.51

2008 16.92 0.40 20.20 0.44

2011 22.75 0.61 22.75 0.61

Appendix Table 8. Estimates and standard errors for Figure 4.1.2. Adjusted and unadjusted 

rates for driver in a traffic stop, 2002–2011

Unadjusted Adjusted

Year Percent SE Percent Percent SE Percent

2002 7.79% 0.19% 9.95% 0.22%

2005 7.82 0.28 9.99 0.32

2008 7.47 0.24 9.55 0.28

2011 8.96 0.36 8.96 0.36

Appendix Table 9. Estimates and standard errors for Figure 4.1.3. Adjusted and unadjusted 

rates for passenger in a traffic stop, 2002–2011

Unadjusted Adjusted

Year Percent SE Percent Percent SE Percent

2002 0.57% 0.04% 2.37% 0.09%

2005 0.55 0.05 2.29 0.13

2008 0.48 0.04 2.03 0.11

2011 1.97 0.14 1.97 0.14
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 42

Appendix Table 10. Estimates and standard errors for Figure 4.1.4. Adjusted and unadjusted 

rates for traffic accident, 2002–2011

Unadjusted Adjusted

Year Percent SE Percent Percent SE Percent

2002 2.73% 0.10% 2.73% 0.10%

2005 2.39 0.13 2.39 0.13

2008 2.07 0.11 2.07 0.11

2011 2.29 0.15 2.29 0.15

Appendix Table 11. Estimates and standard errors for Figure 4.1.5. Adjusted and unadjusted 

rates for reported crime or problem to police, 2002–2011

Unadjusted Adjusted

Year Percent SE Percent Percent SE Percent

2002 5.55% 0.16% 8.74% 0.21%

2005 4.53 0.20 7.13 0.26

2008 3.42 0.15 5.38 0.20

2011 6.96 0.31 6.96 0.31

Appendix Table 12. Estimates and standard errors for Figure 4.1.6. Adjusted and unadjusted 

rates for use or threat of force, 2002–2011

Unadjusted Adjusted

Year Percent SE Percent Percent SE Percent

2002 1.48% 0.12% 2.42% 0.16%

2005 2.29 0.22 3.75 0.29

2008 1.94 0.20 3.19 0.26

2011 4.15 0.35 4.15 0.35
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 43

Appendix Table 13. Estimates and standard errors for Figure 4.1.7. Adjusted and unadjusted 

rates for arrest, 2002–2011

Unadjusted Adjusted

Year Percent SE Percent Percent SE Percent

2002 2.88% 0.18% 2.88% 0.18%

2005 2.91 0.32 2.91 0.32

2008 2.86 0.25 2.86 0.25

2011 3.11 0.30 3.11 0.30

Appendix Table 14. Estimates and standard errors for Figure 4.1.8. Adjusted and unadjusted 

rates for police behaved properly, 2002–2011

Unadjusted Adjusted

Year Percent SE Percent Percent SE Percent

2002 90.09% 0.48% 90.09% 0.48%

2005 90.35 0.69 90.35 0.69

2008 89.68 0.67 89.68 0.67

2011 91.12 0.77 91.12 0.77
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 44

Appendix Table 15. Standard errors for Appendix Table 3. Respondents with face-to-face 

contact with police, by questionnaire and demographic characteristics, 2011

 Initial (2008) Questionnaire Revised (2011) Questionnaire

SE Number SE Percent SE Number SE Percent

Overall 3,306,900 1.4% 1,479,900 0.6%

Sex

Male 2,164,200 1.7% 1,031,700 0.8%

Female 2,231,400 1.6 979,600 0.7

Race

Whitea 2,756,300 1.6% 1,233,800 0.7%

Black/African Americana 842,900 2.3 406,300 1.2

Hispanic/Latino 810,500 2.2 387,200 1.0

Othera,b 371,900 2.4 205,600 1.4

Two or more races 192,600 6.0 112,100 3.2

Age

16–17 272,700 2.7% 144,200 1.5%

18–24 1,177,300 2.8 509,700 1.3

25–34 1,333,600 2.5 586,100 1.1

35–44 1,088,800 2.3 537,700 1.1

45–54 1,117,600 2.1 534,200 1.0

55–64 916,100 2.2 435,300 1.0

65 or older 642,400 1.4 356,200 0.8

a

Excludes persons of Hispanic origin.

b

Includes American Indian and Alaska Natives; Asian, Native Hawaiian, and Other Pacific Islanders.
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 45

Appendix Table 16. Standard errors for Appendix Table 4. Respondents who experienced 

arrest during their most recent contact with police, by questionnaire and demographic 

characteristics, 2011

Initial (2008) Questionnaire Revised (2011) Questionnaire

SE Number SE Percent SE Number SE Percent

Overall 129,900 0.27% 169,000 0.30%

Sex

Male 102,800 0.43% 134,500 0.44%

Female 63,000 0.26 78,200 0.29

Race

Whitea 95,800 0.27% 111,800 0.28%

Black/African Americana 56,300 0.96 65,500 0.93

Hispanic/Latino 36,900 0.69 58,800 0.91

Othera,b -- -- 26,200 1.09

Two or more races -- -- 13,400 1.44

Age

16–17 -- -- 15,000 1.10%

18–24 51,600 0.55% 84,400 0.84

25–34 76,000 0.66 78,500 0.64

35–44 44,700 0.54 51,600 0.49

45–54 39,100 0.46 41,300 0.40

55–64 18,300 0.30 32,000 0.43

65 or older -- -- 16,600 0.31

-- Number rounds to less than 0.5.

a

Excludes persons of Hispanic origin. b

Includes American Indian and Alaska Natives; Asian, Native Hawaiian, and Other Pacific Islanders.
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 46

Appendix Table 17. Standard errors for Appendix Table 5. Respondents who experienced 

use or threat of force during the most recent contact, by questionnaire and demographic 

characteristics, 2011

Initial (2008) Questionnaire Revised (2011) Questionnaire

SE Number SE Percent SE Number SE Percent

Overall 298,800 0.6% 203,500 0.4%

Sex

Male 222,000 0.9% 154,600 0.5%

Female 150,100 0.6 102,700 0.4

Race

Whitea 221,400 0.6% 142,800 0.3%

Black/African Americana 102,500 1.8 69,800 1.0

Hispanic/Latino 69,800 1.3 71,400 1.1

Othera,b 23,100 1.4 21,300 0.9

Two or more races 34,600 5.3 16,800 1.8

Age

16–17 -- -- 24,700 1.7%

18–24 116,100 1.2% 99,300 1.0

25–34 152,000 1.3 87,700 0.7

35–44 83,900 1.0 59,600 0.6

45–54 87,200 1.0 52,900 0.5

55–64 64,200 1.0 35,800 0.5

65 or older -- -- 30,500 0.6

-- Number rounds to less than 0.5.

a

Excludes persons of Hispanic origin.

b

Includes American Indian and Alaska Natives; Asian, Native Hawaiian, and Other Pacific Islanders.
Police-Public Contact Survey: Assessment and Recommendations for Producing Trend Estimates 

after 2011 Questionnaire Redesign 47

Appendix Table 18. Standard errors for Appendix Table 6. Number and percent of 

respondents with perceptions that police behaved properly during most recent contact in 

2011, by questionnaire and demographic subdomains

Initial (2008) Questionnaire Revised (2011) Questionnaire

SE Number SE Percent SE Number SE Percent

Overall 3,090,600 2.0% 1,469,200 0.7%

Sex

Male 1,979,000 2.7% 1,005,700 0.9%

Female 2,092,000 2.3 989,000 0.9

Race

Whitea 2,587,100 2.1% 1,241,000 0.8%

Black/African Americana 739,800 4.6 373,100 1.7

Hispanic/Latino 746,700 3.8 377,200 1.6

Othera,b 339,500 6.0 199,400 2.0

Two or more races 148,900 11.5 108,100 2.9

Age

16–17 268,700 3.1% 134,300 3.0%

18–24 1,089,700 3.3 479,900 1.4

25–34 1,210,800 3.4 579,500 1.2

35–44 1,003,300 3.4 543,500 1.2

45–54 1,021,900 3.4 533,600 1.2

55–64 845,600 3.5 440,100 1.3

65 or older 608,100 3.4 361,000 1.2

a

Excludes persons of Hispanic origin.

b

Includes American Indian and Alaska Natives; Asian, Native Hawaiian, and Other Pacific Islanders.