Murphy, Gerard, Molly Griswold, Bruce Kubu, Daniel Woods, Colleen Berryessa, Kevin Greene, and Jacob Berman. National Survey of Eyewitness Identification Procedure in Law Enforcement Agencies, 1994-2012. ICPSR34274-v1. Ann Arbor, MI: Inter-university Consortium for Political and Social Research [distributor], 2014-03-07. https://doi.org/10.3886/ICPSR34274.v1
Persistent URL: https://doi.org/10.3886/ICPSR34274.v1
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Smallest Geographic Unit:
Date of Collection:
Unit of Observation:
law enforcement agency
All functioning United States police agencies listed within the National Directory of Law Enforcement Agencies (NDLEA) database in 2011, that perform full service police duties (N=15,685).
Data Collection Notes:
The study associated with the data (Murphy, Donaldson, Kubu, Woods, Berryessa, Greene, and Berman, 2012; NIJ 2010-IJ-CX-0032) discusses qualitative data collected from 30 interviews via telephone as a supplement to the survey. This data will not be released by ICPSR at this time.
The purpose of the study was to create the first nationwide assessment of the criminal justice system regarding eyewitness identification procedures used by law enforcement agencies including through conducting a national survey of a random stratified sample of law enforcement agencies in the United States regarding their eyewitness identification policies, training, and police procedures.
The Eyewitness Identification Survey was developed in consultation with a Technical Advisory Group (TAG) comprised of academic researchers and law enforcement experts. The survey was fielded in order to evaluate the current eyewitness identification policies and practices in law enforcement agencies throughout the United States. A focus group of the eight TAG members examined the major issues to be included in the survey and to identify questions that would effectively evaluate current practices in the field. The draft of the Eyewitness Identification Survey was sent to representatives from nine law enforcement agencies in June and July of 2011. Agencies were chosen based on their past experiences with and expertise regarding eyewitness identification procedures and policy development. These pilot testers were asked to complete the survey and make margin notes concerning questions about the form and content. Each person was then contacted via telephone to discuss the survey. The final version of the survey was made available to respondents online as well as in hard copy.
The National Eyewitness Identification Survey was distributed to a random stratified sample of law enforcement agencies throughout the United States (n=1,377). Hard copies of the survey were mailed to agencies on three separate occasions between August 17 and October 25, 2011. Reminder letters were sent to non-responding agencies in five separate waves between October 18, 2011 and January 11, 2012. Reminder telephone calls were placed to a number of non-respondent agencies between January 17 and January 24, 2012. A total of 619 completed surveys were returned.
When the surveys were returned they were recorded and reviewed for completion. Surveys with information that was considered unclear, inconsistent, or missing were flagged. PERF staff members contacted respondents for all flagged surveys for clarification or missing response. Staff members attempted to contact respondents of missing data through mid January 2012.
The study contracted with Tailored Statistical Solutions, LCC (TS²) to draw a nationally representative sample of law enforcement agencies from the National Directory of Law Enforcement Agencies (NDLEA) database. In addition to the name and address of the current chief executive, NDLEA information included the population served by the law enforcement agency, the type of law enforcement agency, the number of officers in the agency, and the region (Northeast, Midwest, South, and West) in which the agency is located. The data base was cleaned to omit agencies that are defunct or do not perform full service police duties. After cleaning the database contained information on 15,685 law enforcement agencies.
The law enforcement agencies in the database were stratified by region, type, and size based on the number of sworn officers reducing the sample to 1,401 agencies. Of those, 24 agencies reported not using any eyewitness identification procedure and were not sent the survey. Of the 1,377 agencies sent the survey, 619 were completed.
Each of the agencies selected for the sample was weighted (using variable FINALWTALL "WEIGHT") in order to account for population size.
Mode of Data Collection:
National Directory of Law Enforcement Agencies (NDLEA)
Description of Variables:
The 515 variables contained in the study include:
1) Agency information.
2) Current policies including: instructions given to eyewitness pre-lineup, lineup procedure, lineup content, lineup presentation method, and behavioral influence of the lineup administrator.
Lineup procedures include: show up, photographic lineup, live lineup, composite, and mugshot search.
3) Historical agency experiences.
Of the 1,377 agencies sent the survey, 619 completed the survey resulting in a response rate of 45 percent.
Presence of Common Scales:
Extent of Processing: ICPSR data undergo a confidentiality review and are altered when necessary to limit the risk of
disclosure. ICPSR also routinely creates ready-to-go data files along with setups in the major
statistical software formats as well as standard codebooks to accompany the data. In addition to
these procedures, ICPSR performed the following processing steps for this data collection:
Standardized missing values.
Checked for undocumented or out-of-range codes.