Weisburd, D., Groff, E. R., Jones, G., Cave, B., Amendola, K. L., Yang, S. M., & Emison, R. F. (2015). The Dallas patrol management experiment: can AVL technologies be used to harness unallocated patrol time for crime prevention?. Journal of Experimental Criminology, 11(3), 367-391.
Location in the Matrix and Methodological Rigor:
Neighborhood, General, Proactive; Very Rigorous; No evidence of an effect
What police practice or strategy was examined?
The study examined whether information on police patrol drawn from automatic vehicle location (AVL) systems could be used to increase the amount of directed patrol time at (1) high-crime police beats and (2) crime hot spots, and whether such increases would lead to reductions in crime. Summarized here are the findings from the beat-level analysis. Police agencies often use crime counts at beats or hot spots to allocate patrol resources for directed patrol. However, in this study, commanders were also given weekly reports that included the following information for both beats and hot spots within those beats: the amount of attention each commander had requested for those areas from the previous week; the amount of patrol time received in each type of area as measured by AVL; and more specifically, the amount of patrol time in each area that was “unallocated” to a given call for service as measured by AVL. Managers then used the reports in weekly Compstat meetings held within each division, during which emerging problems and hot spots were identified for increased attention. The study tested whether supervisor knowledge of unallocated patrol time using AVL data could be successfully used to redirect resources to higher crime beats and therefore deter crime at the beat level.
How was the intervention evaluated?
Utilizing a block-randomized experimental design, 232 police beats were randomly allocated to an experimental or control condition. The information described above was provided to commanders in the experimental beats but not to the control beats where standard police patrol was implemented. A composite measure of crime based on incident data was used that included a range of violent and property offences. Over a 13-week period, assigned patrol time, unallocated patrol time, total patrol time, and crime were tracked and compared at police beats.
What were the key findings?
This process of providing information to commanders for their Compstat discussions did not lead to significant increases in patrol time in experimental beats, and also did not have a deterrent impact on crime at the beat level.
What were the implications for law enforcement?
In the overall study, crime went down significantly at hot spots level but not the beat level. The authors suggest this may be because the beat-level patrol dosage was too low. Efforts to transform unallocated patrol time in sufficient dosage to create general deterrent impacts in a city are constrained by the commitment of police to a philosophy of 911 rapid response that demands the spread of police patrol resources across a city.
Where can I find more information about this intervention, similar types of intervention, or related studies?
Dallas AVL study at the hot spot level (link coming soon)