Kennedy, L. W., Caplan, J. M., & Piza, E. L. (2015). A multi-jurisdictional test of risk terrain modeling and place-based evaluation of environmental risk-based patrol deployment strategies. Rutgers Center on Public Security, Newark, NJ.
See also Caplan, J.M. and Kennedy, L.W. (2016). Risk Terrain Modeling: Crime Prediction and Risk Reduction. (University of California Press).
Location in the Matrix and Methodological Rigor:
Micro places, Focused, Proactive; Rigorous; Effective
What police practice or strategy was examined?
The quasi-experimental study evaluated police intervention strategies targeted at high-risk micro-level environments derived from risk terrain modeling (RTM) across 5 cities. Summarized here is the Glendale, AZ study, which focused on robbery. The RTM analysis yielded seven significant risk factors associated with robbery including areas with high levels of drug-related calls for service, convenience stores, take out restaurants, apartment complexes, gang member residences, liquor stores, and bars. Using this information, Glendale Police Department designed its intervention to address all seven risk factors and conducted an array of activities including directed patrols, flyer distribution, community meetings, and proactive community engagement. The intervention lasted for three months.
How was the intervention evaluated?
Control street units were identified using a Two Nearest Neighbors propensity score matching technique. Matching variables included whether the street unit intersected a high-risk street unit or a high-risk cell as identified by the RTM analysis, whether the unit was a segment or an intersection, the concentrated social disadvantage and racial heterogeneity in surrounding census block group, as well as pretest levels of crime and proactive police actions. Robbery incidents during the three-month intervention period and the three-month post-intervention period were compared to the figures during the same periods from the previous year in the treatment and control areas.
What were the key findings?
Robbery decreased by 42% in the target area as compared to the control area during the intervention (p<0.1) but increased by 38% post-intervention although not significantly. No significant effects were found at the micro-street unit level in either the during- or post-intervention period. An additional evaluation that disaggregated the various intervention strategies suggests that directed patrols were associated with a short-term reduction of robbery whereas flyer distribution was associated with post-intervention reduction of robbery. Additionally, the study authors found a diffusion of benefits of the patrols.
What were the implications for law enforcement?
The authors suggest that the RTM approach enables the police to make decisions about where to allocate resources and what to do at high-risk places to deter crime. The intervention adopted by GPD was demonstrated to be effective in reducing robbery during the intervention activities, but ceased once policing efforts returned to the status quo. Flyer distribution seemed to have a linger crime reduction effect after the distribution of flyers ceased.
Where can I find more information about this intervention, similar types of intervention, or related studies?