License plate readers (LPRs) are a sensory and information technology designed to match scanned license plates to databases related to stolen vehicles, motor vehicle violations, criminal investigations and other policing matters. Preliminary assessments of LPRs focused on the efficiency of the technology itself, not its crime control or cost-effectiveness. Given the scant evidence-base for LPRs use in an environment of rapid diffusion, adaptation and costs, the researchers proposed to study the crime control and cost-benefit/effectiveness of LPRs. The study sought to analyze the impact of technology on the police, the use of LPRs by law enforcement, and also to improve the evidence-base of patrol and investigative operations.
This two-year project had four major study phases. It should be noted that the unit of analysis for each of the four procedures listed below is either the "police agency", "geographic areas", or "crime investigations".
The four phases of this study were:
1. A national police agency survey on license plate readers (LPRs) adoption. This survey updated Lum et al.'s (2010) 2009 national survey on LPRs use, and expanded on the earlier survey with more specific inquiries about LPRs adoption, deployment, data, and effectiveness.
2. A large scale experimental evaluation was conducted to more rigorously examine the crime control potential of LPRs in problem-oriented, proactive, place-based, and focused deterrence contexts. Through this evaluation, "tricks of the trade" of how officers could use LPRs to enhance their patrol capabilities were also documented.
3. An exploratory evaluation of police LPRs use for investigations.
4. Cost-benefit and cost-effectiveness analyses were undertaken for LPRs use in patrol and investigations, respectively. Specifically measured was whether LPR use led to a cost benefit in terms of crimes prevented in patrol deployment and whether or not the use of LPRs led to cost effectiveness in investigations compared to investigations that did not employ it.
A national, stratified, representative survey of law enforcement agencies with over 100 sworn officers in the United States was conducted using the 2007 Law Enforcement Management and Administrative Statistics (LEMAS) survey of state and local law enforcement agencies.
Agencies were drawn from three categories:
1. Agencies with 500 or more officers.
2. Agencies that responded "yes" to using license plate readers (LPRs) in the LEMAS 2007 on a "regular basis" (166 agencies).
3. A 25% random sample of agencies with 100 to 499 sworn officers that did not use LPRs in 2007.
The final sample included 431 police and sheriff's agencies with law enforcement responsibilities.
Law enforcement agencies with over 100 sworn officers located in the United States.
Data-file-for-2013-IJ-CX-0017.sav (n=329; 94 variables): this file includes data derived from surveys conducted at police agencies with over 100 sworn officers located in the United States. Variables include information about an agency's use of license plate readers (LPRs), the types of crimes using LPRs, the number of LPRs in an agency, funding sources for LPRs, reasons for using or not using LPRs, the types of information that are regularly accessed by LPRs, how LPRs data are accessed and collected, policy on LPRs use, levels of satisfaction and dissatisfaction with LPRs, and the future of LPRs in the agency.
A demographic variable includes an agency's number of authorized full time personnel.
Several Likert-type scales were used.