Evan T. Sorg

DOES WHAT POLICE DO AT HOT SPOTS MATTER? THE PHILADELPHIA POLICING TACTICS EXPERIMENT*

Policing tactics that are proactive, focused on small places or groups of people in small places, and tailor specific solutions to problems using careful analysis of local conditions seem to be effective at reducing violent crime. But which tactics are most effective when applied at hot spots remains unknown. This article documents the design and implementation of a randomized controlled field experiment to test three policing tactics applied to small, high-crime places: 1) foot patrol, 2) problem-oriented policing, and 3) offender-focused policing. A total of 81 experimental places were identified from the highest violent crime areas in Philadelphia (27 areas were judged amenable to each policing tactic). Within each group of 27 areas, 20 places were randomly assigned to receive treatment and 7 places acted as controls. Offender-focused sites experienced a 42 percent reduction in all violent crime and a 50 percent reduction in violent felonies compared with their control places. Problem-oriented policing and foot patrol did not significantly reduce violent crime or violent felonies. Potential explanations of these findings are discussed in the contexts of dosage, implementation, and hot spot stability over time.

Boundary Adherence during Place-based Policing Evaluations: A Research Note

Objectives: This note explores complications with standard methods to evaluate place-based policing interventions. It identifies and explains issues of boundary misspecification during evaluation as a result of boundary adjustment by police during an intervention. Method: Using geographic data gathered during post-experiment focus groups with officers involved in the Philadelphia Foot Patrol Experiment, we highlight the practice of boundary adjustment on the part of officers and we explain why such adjustments occurred. Results: Officers involved in the focus groups who identified the active boundaries of their hot spot assignments (n = 124) all reported policing outside of their delineated beats. On average, their active beats were 0.13 square miles larger than the originally delineated treatment beats. Some active beats overlapped catchment and control locations. Conclusion: Boundary misspecification could cause researchers to (1) incorrectly label a direct benefit of receiving treatment as a diffusion of crime control benefits; (2) underestimate immediate spatial crime displacement; and (3) underestimate treatment effects. Future place-based experiments should take into account the various pressures on officers to adjust the boundaries of their assignments by incorporating measures that track boundary adherence over time (and reporting them) in order to optimize assessments of net effects, diffusion and displacement.

Satisfaction With Police in Violent Crime Hot Spots Using Community Surveys as a Guide for Selecting Hot Spots Policing Tactics

This article argues that citizens’ perceptions of police can aid in selecting appropriate hot spots policing tactics and models satisfaction with police as evidenced by respondents who live or work in violent crime hot spots. Survey data (N = 630) were collected by randomly sampling addresses within violent crime hot spots in Philadelphia, Pennsylvania, USA. The results reveal that being younger, or more educated, or perceiving higher procedural injustice, or higher social disorder, or being more fearful of crime, all link to lower satisfaction with police in violent crime hot spots. To maintain or improve public satisfaction with police services in hot spots, police departments should adopt tactics that are not only effective in reducing crime but also procedurally just, reduce fear of crime, and address social disorder problems.

Explaining Dosage Diffusion During Hot Spot Patrols: An Application of Optimal Foraging Theory to Police Officer Behavior

Drawing from the concepts of optimal foraging theory, this paper presents and tests the assumptions of a foraging theory of police behavior during hot spots patrols. The theory explains why, over time, officers involved in hot spots policing interventions would leave the hot spots they are assigned to police and begin working within other locations. We test what factors influence the amounts of activity that officers undertake outside of their assigned hot spots and at nearby streets using data gathered as part of the Philadelphia Foot Patrol Experiment. Officers performed more activity outside of their beats as the experiment progressed. Several theoretically relevant variables predict the level of activity that officers perform outside their beats, including the size of the target area and the amounts of crime occurring within and outside of the target area. “Dosage diffusion” might be one reason why hot spot interventions have diminishing effects over time. From an optimal foraging theory perspective, hot spots requiring police officers to constrain their actions to pre-defined areas can be perceived as counter-intuitive by the officers, especially over extended periods of time. The results of this study support the suggestion that hot spots patrols should be short-term and randomly rotated across hot spots.

Operation Thumbs Down: A quasi-experimental evaluation of an FBI gang takedown in South Central Los Angeles

Purpose The purpose of this paper is to evaluate the violence-reduction effects following an FBI-led gang takedown in South Central Los Angeles. Design/methodology/approach The time series impact of the intervention was estimated using a Bayesian diffusion-regression state-space model designed to infer a causal effect of an intervention using data from a similar (non-targeted) gang area as a control. Findings A statistically significant 22 percent reduction in violent crime was observed, a reduction that lasted at least nine months after the interdiction. Research limitations/implications The research method does make assumptions about the equivalency of the control area, though statistical checks are employed to confirm the control area crime rate trended similarly to the target area prior to the intervention. Practical implications The paper demonstrates a minimum nine-month benefit to a gang takedown in the target area, suggesting that relatively long-term benefits from focused law enforcement activity are possible. Social implications Longer-term crime reduction beyond just the day of the intervention can aid communities struggling with high crime and rampant gang activity. Originality/value Few FBI-led gang task force interventions have been studied for their crime reduction benefit at the neighborhood level. This study adds to that limited literature. It also introduces a methodology that can incorporate crime rates from a control area into the analysis, and overcome some limitations imposed by ARIMA modeling.