Problem‐oriented policing for reducing crime and disorder: An updated systematic review and meta‐analysis

BACKGROUND: Herman Goldstein developed problem‐oriented policing (POP) to focus police on more proactively addressing chronic problems, rather than using traditional reactive efforts. POP has been utilized to target a wide range of problems and has become commonly used in agencies across the United States and the world, although implementation is often uneven. POP interventions commonly use the SARA (scanning, analysis, response, assessment) model to identify problems, carefully analyze the conditions contributing to the problem, develop a tailored response to target these underlying factors, and evaluate outcome effectiveness. OBJECTIVES: To extend and update the findings of the original POP systematic review by synthesizing the findings of published and unpublished evaluations of POP through December 2018 to assess its overall impacts on crime and disorder. The review also examined impacts of POP on crime displacement, police financial costs, and noncrime outcomes. SEARCH METHODS: Searches using POP keywords of the Global Policing Database at the University of Queensland were conducted to identify published and unpublished evaluations between 2006 and 2018. We supplemented these searches with forward searches, hand searches of leading journals and the Center for Problem‐Oriented Policing, and consultation with experts. SELECTION CRITERIA: Eligible studies had to include a target area or group that received a POP intervention AND a control area/group that received standard police services. The control condition could be either experimental or quasi‐experimental. Units of analysis could be places or people. We defined POP as studies that generally followed the tenets of the SARA model. DATA COLLECTION AND ANALYSIS: We identified 39 new (published between 2006 and 2018) studies that met our eligibility criteria as an evaluation of POP. Twenty‐four of these studies had sufficient data available to calculate an effect size. Along with the 10 studies from our initial systematic review of POP, these 34 studies are included in our meta‐analytic review of POP. Nine of these studies were randomized experiments and 25 were quasi‐experiments. We calculated effect sizes for each study using Cohen's D and relative incidence risk ratios and used random effects meta‐analyses to synthesize studies. RESULTS: Our meta‐analyses suggest statistically significant impacts of POP. Our relative incident risk ratio analysis of mean effects suggests a 33.8% reduction in crime/disorder in the POP treatment areas/groups relative to the controls. We find no evidence of significant crime displacement as a result of POP and some evidence for a greater likelihood of a diffusion of crime control benefits. Few studies assessed noncrime outcomes, but our narrative review suggests POP is cost‐effective, but has limited impacts on fear of crime, legitimacy, and collective efficacy. AUTHORS’ CONCLUSIONS: Our review provides strong and consistent evidence that POP is an effective strategy for reducing crime and disorder. There is a great deal of heterogeneity in the magnitude of effect sizes across factors such as study type, study rigor and crime type. Despite this heterogeneity, 31 out of 34 studies (91.2%) have effect sizes in favor of a treatment effect and the overall mean effect is positive and significant in all of our models.