LPR for Researchers

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The Research Agenda

There are currently only a few rigorous evaluations that examine the outcome effectiveness of police technology on crime and disorder. Only two experimental evaluations of the crime control effectiveness of LPR technologies exist: the first was conducted by the Police Executive Research Forum, and the second is the GMU evaluation.

The Matrix Confirms this Dearth of Research

The Evidence-Based Policing Matrix, which currently houses all moderately rigorous to highly rigorous evaluation studies of police interventions on crime, confirms this gap in existing research. Almost all of the evaluation studies in the Matrix are not conducted on the effectiveness of police technologies, but rather on deployment schemes (e.g., hot spots patrol, crackdowns), problem solving approaches, arrest policies, or interagency deterrence or problem-oriented strategies (e.g., pulling levers, nuisance abatement). Often, the effectiveness of a technology is assumed from its efficiency or because it is a natural part of another strategy. For example, computerized crime mapping is used to create hot spots for directed patrol strategies. We know with great certainty that hot spot policing is effective in reducing crime at places, but this does not mean that the existence or use of crime maps can lead to measurable crime reduction effects.

Rapid Diffusion of LPR Technology Requires Evaluation Research to Keep Up

Both the GMU 2010 and 2014 national surveys indicate that at least for large police agencies, there is a rapid diffusion of adoption of LPR technologies. In many cases the question of whether LPR should be adopted at all is a moot issue; police agencies buy or acquire technologies in the absence of evaluation. In this environment, researchers can still contribute by evaluating ways that LPR is used and determining the most optimal way LPR can be deployed. We encourage researchers to consider experimental and quasi-experimental evaluations of LPR and other emerging and rapidly diffusing technologies.

Some Considerations for LPR Deployment

A two-part discussion and slide show by the Principal Investigator from George Mason, Dr. Cynthia Lum, and the LPR project manager at SPAWAR, Mr. Matt Snyder about relevant issues for deploying LPR.

Ideas for Future Research Questions and Projects

The CEBCP LPR research team is currently conducting a new survey and research on LPR use in patrol and investigations.
Conduct more experimental and rigorous quasi-experimental tests on different uses of LPR at hot spots and hot routes. (See the PERF experiments, which compare LPR hot spot patrol with non-LPR specialized unit patrol, and were the first conducted on LPR).
Examine the differences in crime detection, prevention, and deterrence outcomes between fixed, mobile, and combined approaches using LPR technology.
Examine the impact of LPR on officer safety during patrol.
Examine the impact and use of LPR on traffic-related concerns.
Examine the impact of various uses of LPR on citizen-police legitimacy (see Chapter 4 of the GMU report for a research agenda).
Study the relationship between police technologies and police officers, organizational culture, and deployment choices (see GMU’s 2014 technology study).
Examine the impact of broadening the database that LPR scanners access on detection rates and crime prevention outcomes.
Examine the impact of using information collected by LPR systems on the effectiveness of crime prevention strategies.
Examine whether LPR has an effect on clearance rates of different types of crimes, and whether such an effect impacts deterrence.

Research papers written about LPR by the GMU scholars

Koper, C.S., & Lum, C. (2018). Effectiveness of License Plate Readers for Patrol and Investigations. The Police Chief, September 2018, 14-15.
Koper, C.S., & Lum, C. (2019). The impacts of large-scale license plate reader deployment on criminal investigations. Police Quarterly, 22(3), 305-329.
Koper, C.S., Lum, C., Willis, J.J., Happeny, S., Johnson, W.D., Nichols, J., Stoltz, M., Vovak, H., Wu, X., & Nagin, D.S. (2018). Evaluating the Crime Control and Cost-Benefit Effectiveness of License Plate Recognition (LPR) Technology. Final Report to the National Institute of Justice. Fairfax, VA: Center for Evidence-Based Crime Policy, George Mason University.
Koper, C.S., Lum, C., Wu, X., Johnson, W., & Stoltz, M. (2022). Do license plate readers enhance the initial and residual deterrent effects of police patrol? A quasi-randomized test. Journal of Experimental Criminology, 18, 725-746.
Lum, C., Hibdon, J., Cave, B., Koper, C.S., & Merola, L. (2011). License plate reader (LPR) police patrols in crime hot spots: An experimental evaluation in two adjacent jurisdictions. Journal of Experimental Criminology, 7(4), 321-345.
Lum, C., Koper, C.S., Willis, J.J., Happeny, S., Vovak, H., & Nichols, J. (2019). The rapid diffusion of license plate readers in US law enforcement agencies. Policing: An International Journal of Police Strategies and Management, 42(3), 376-393.
Lum, C., Merola, L., Willis (Hibdon), J., & Cave, B. (2010). License Plate Recognition Technologies for Law Enforcement: Impact Evaluation and Community Assessment. Fairfax, VA: Center for Evidence-Based Crime Policy, George Mason University.
Merola, L., & Lum, C. (2012). Privacy and the impact of emerging surveillance technologies: The case of license plate recognition technology. Judicature, 96(3), 119-126.
Merola, L., & Lum, C. (2014). Predicting public support for the use of license plate recognition technology by police. Police Practice and Research, 15(5): 373-388.
Merola, L., & Lum, C. (2015). Understanding Citizen Support for License Plate Readers. Translational Criminology, 8 (Spring 2015), 23-25.
Merola, L., Lum, C., Cave, B., & Hibdon, J. (2014). Community support for license plate recognition. Policing: An International Journal of Police Strategies and Management, 37(1), 30-51.
Merola, L., Lum, C., & Murphy, R. (2018). The impact of license plate recognition technology (LPR) on trust in law enforcement: A survey-experiment. Journal of Experimental Criminology, 15(1), 55-66.
Willis, J.J., Koper, C.S., & Lum, C. (2018). The adaptation of license-plate readers for investigative purposes: Police technology and innovation re-invention. Justice Quarterly, 35(4), 614-638.