2011_PPCS_OMB_SS with Passback Part B Final

B. Description of Statistical Methodology

1. Universe and Respondent Selection

The Police Public Contact Survey has been conducted as a special supplement to the NCVS every three years since 1999. The PPCS is a nationally representative sample of individuals aged 16 and older living in U.S. households. It does not interview anyone aged 12 to 15 living in the household.

The survey items are designed to address specific issues that can be directly related to one’s age – in particular being stopped by police while driving a vehicle. The 1996 pretest suggested that data collected from juveniles between the age of 12 and 15 did not have a significant impact on the key outcome variables: prevalence of contact and use of force. As a result, it was decided at that time to exclude youth under age 16.

In 2008, the majority of respondents who reported having interaction with police stated the contact was traffic related. In an estimated 44% of these stops, the respondent was the driver. Since persons under the age of 16 are not eligible for a drivers’ license in most states, inclusion in the PPCS would likely show that almost all of the 12 to 15 year olds involved in the traffic stops were passengers.

The Police Public Contact Survey was designed to be administered to an adult population. There would be a significant investment of resources to revise the collection for 2011 to be appropriate for a younger population, including a revised questionnaire and additional cognitive tests for the younger age group. In addition, there would be significant issues with comparability with the past 10 years of data that have been limited to a sample of respondents age 16 and older.

In combination with the higher data collection costs and lower response rates among persons in this age group, we believe that it is prudent to continue to exclude persons under age 16 from the PPCS.

The PPCS does not interview homeless persons, persons who are institutionalized or incarcerated at the time of the interview, or persons living in military barracks. The survey collects detailed information on the interactions people have with police, including contacts in which police use or threaten force. Findings from this survey are based solely on the personal accounts of the PPCS respondents. Official police records on contacts between police and the public are not used for this survey.

Administering the Police Public Contact Survey as a supplement to the National Crime Victimization Survey (NCVS) leverages the NCVS sample to obtain additional information from NCVS household members on any contacts they have had with the police. So, to fully understand the PPCS one must first understand the NCVS sample design, the foundation on which the PPCS rests.

The NCVS was deemed to be the most practical means for obtaining information on this issue since it is an ongoing survey in which interviews are conducted with the American public concerning recent crime victimization experiences. The NCVS provides national data on personal and household victimizations both reported and not reported to the police. The survey was initiated by the Law Enforcement Assistance Administration to fulfill the mandate set forth by Section 515b of Public Law 93-83 to collect, evaluate, publish, and disseminate information on the progress of law enforcement within the United States. The NCVS was transferred to the BJS in December 1979. Currently, Title 42, United States Code, Section 3732 of the Justice Systems Improvement Act of 1979, authorizes the BJS to collect statistics on victimization.

The sample universe for the PPCS is all persons aged 16 or older in all NCVS households. Approximately 15,117 persons a month, age 16 and older, in these households will be eligible to be interviewed for the supplement during July through December 2011 for a total of 90,700 possible interviews.

Generally, interviewers are able to obtain interviews for the NCVS with approximately 80 percent of the PPCS eligible household members in 90 percent of the occupied units in sample in any given month. We expect a total of 72,560 individuals aged 16 and older to be interviewed during the 6 month collection period.

2. Procedures for Collecting Information

For the six month period, July through December 2011, covering the 2011 PPCS we expect the national sample will be approximately 64,380 designated households. The sample is located throughout the country. Furthermore, the sample consists of six parts, each of which is designated for interview in a given month and again at 6-month intervals; for example, July and January, August and February, September and March, and so forth. The sample is based solely on 2000 decennial Census sample.

The NCVS uses a rotating sample (see attachment 8). The sample consists of six groups for each month of enumeration. Each of these groups stays in sample for an initial interview and six subsequent interviews. The initial interview is essentially a bounding interview, which establishes a reference period, reduces telescoping into the reference period, and enables the interviewer to avoid recording duplicate reports on subsequent visits. Traditionally, the NCVS estimates exclude the bounding interview, however, beginning with the 2007 NCVS estimates this all changed. In an effort to reduce program costs, the NCVS sample was reduced by 14 percent in July 2007. To offset this reduction in sample and maintain an equivalent sample size as a basis for the 2007 NCVS estimates, the program sponsor decided to begin including the bounding interview in the NCVS estimates. During the course of a 6-month period, we interview a full sample of six rotation groups--one-sixth each month. In addition, one rotation group enters the sample for its bounding interview each month.

Each interview period, the interviewer updates NCVS control card information (demographics) for each member listed on the household roster that is 12 years old or older by interviewing the household respondent. The household respondent is usually a person who is 18 years of age or older who is knowledgeable about the household and its members. Once household composition and demographics are collected the interview proceeds by asking the household respondent about their victimization experiences 6 months prior to the date of interview. If the respondent has been victimized additional questions are asked to learn more about the nature and consequences of that victimization. This is repeated for each victimization, and the respondent reports until all victimizations are fully documented. Once complete, the PPCS supplement will be asked, that is, as long as the respondent is 16 years of age and older. Once the PPCS is complete, the next eligible household member 12 years of age or older is asked about their victimization experiences in the last six months followed by the PPCS, if they are eligible. This process is repeated until all eligible members in the household are interviewed or are verified non-interviews. Each household member provides the information by self-response. Proxy interviews are not acceptable for the PPCS, nor are PPCS interviews in a non-English language¹. Proxy interview are allowed for NCVS interviews in very limited circumstances.

The first contact with a household is by personal visit. For the second through seventh visits, we encourage interviews to be conducted by telephone to reduce costs.

3. Methods to Maximize Response

Every effort is being made to make the survey materials clear and straightforward. The PPCS instrument has been designed to make collection of the data as concise and easy for the respondent as possible. The PPCS uses questions that have been used previously in past data collections and are known to be easily understood by most respondents.

In addition, prior to the start of the data collection, the Census Bureau staff mails an introductory letter (NCVS-572(L), NCVS-573(L)) explaining the NCVS to the household before the interviewer's visit or call. The NCVS-572(L) is sent to households that are being contacted for the first time, and the NCVS-573(L) is sent to all households that have been contacted previously. All Census Bureau interviewers are trained about the PPCS instrument, including internal check items that are in place to help the interviewer insure that the respondent is being asked the appropriate questions and follow-up when clarification is needed. The interviewers are also trained to make repeated attempts at contacting respondents and to complete interviews with all eligible household members. Finally, the interviewer obtains demographic characteristics of noninterview persons and the race of noninterview households for use in the adjustment for nonresponse.

4. Testing of Procedures

The majority of the survey questions were tested during the previous collections conducted in 1996, 1999, 2002, 2005, and 2008 and therefore have been pretested and are known to be easily understood and answered. Because of changes to the 2011 screener, the Census Bureau conducted an extensive examination which included an expert review and cognitive testing of the revised screener, minor wording changes to existing questions, and additional questions added to the questionnaire (see attachment 9).

The cognitive testing was conducted by the Center for Survey Measurement at the U.S. Census Bureau, under their generic clearance for questionnaire pretesting research (OMB number 0607-0725). The testing was conducted in two rounds during January and February 2011. In total, 29 individuals were interviewed, 14 in the first round and an additional 15 in the second round. The results of the cognitive test lead to a series of recommendations that have been adopted in the final instrument, and helped to improve the flow and comprehension of the revised screener and questionnaire. Most of the recommendations consisted of changes to the wording of a question to remove any confusion; for instance, the cognitive tests found that respondents were confused by the phrase “initial contact with police”, but were much better able to understand “at the beginning of your most recent contact with police”, so the wording of questions 10 and 38 was changed to improve clarity. There were also questions removed from the questionnaire that were confusing to the respondent. In the initial draft of the instrument, there were a series of questions about use of force during a voluntary contact. These questions confused respondents and led to some issues in recall where respondent was no longer answering questions based on the most recent contact. These questions were removed between the first and second round of cognitive testing, and there were no additional issues found with keeping the respondent focused on their most recent voluntary contact.

Respondent recall has always been a concern when asking for information of past experience. The PPCS has historically shown that of those respondents who have had contact with the police over the past year, approximately three quarters of the respondents have had only one contact. The issue of respondent recall – keeping the respondents’ focus on one event – has been addressed in the 2011 instrument with the addition of directions and reminders that will be read by the interviewer.

The revisions to the 2011 PPCS instrument have been focused on reinforcing the bounding period - by adding detail in the questions to assist the respondent with his or her recall about a specific event. With each set of type of contact questions, the interviewer will read an introduction to the respondent that this is related to the most recent contact. This introduction and interviewer note can be found on pages 3, 13, and 22 of the survey instrument in Attachment 7 of the OMB package. In addition, the CAPI instrument has been designed to provide automatic fills so that the interviewer is able to remind the respondent about the type of contact they reported as their most recent.

The final report outlining these and other recommendations of the cognitive testing is included with this package.

5. Consultation Information

BJS contacts include –

Christine Eith Joel Garner

Statistician Chief, Law Enforcement Unit

Christine.Eith@usdoj.gov Joel.Garner@usdoj.gov

202.305.4559 202.305.2682

The Census Bureau contacts include –

La Terri Bynum

Acting Branch Chief, Crime Surveys Branch

Demographic Surveys Division

Laterri.d.bynum@census.gov

301.763.3858

C. Attachments

1. Language regarding data on use of excessive force (42 USC 14142 [sec. 210402])

2. Copy of the regulatory authority (42 USC 3731 and 3732)

3. M.R. Durose, E Smith, & P. Langan. 2007. Contacts between Police and the Public, 2005. U.S. Department of Justice, Office of Justice Programs, Bureau of Justice Statistics.

4. Introduction letters for the NCVS collection: NCVS-572 and NCVS-573.

5. Copy of the 2008 PPCS survey instrument

6. Summary of 2011 Police Public Contact Survey

7. Copy of the 2011 PPCS survey instrument

8. Summary of NCVS sampling plan

9. Report of Cognitive Testing of the 2011 Police Public Contact Survey Questionnaire

1 Approximately 2% of NCVS interviews are conducted by proxy. The PPCS excludes these proxy interviews. Given the nature of the questions, BJS determined that proxy respondents would have difficulty describing the details of contacts between police and the sampled respondents. For instance, respondents are asked whether they felt the force was excessive; a proxy interview would not know how the sampled respondent felt about the use of force.