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A quasi-experimental synthetic control evaluation of a place-based police-directed patrol intervention on violent crime Journal of Experimental Criminology

NCJ Number
Journal of Experimental Criminology Volume: 14 Issue: 1 Dated: February 2018 Pages: 83-109
Jason Rydberg; Edmund F. McGarrett; Alexis Norris; Giovanni Circo
Date Published
February 2018
27 pages
This research evaluated the impact of the implementation of a place-based police-directed patrol interventionoriginally based on the Data Driven Approaches to Crime and Traffic Safety (DDACTS) modelon violent crime in Flint, Michigan.
The study used recent advances in synthetic control methods to implement a retrospective quasi-experimental design across seven separate intervention areas, producing a counterfactual estimate of what would have happened to violent crime had the intervention never been implemented. Survey weight calibration was used to produce counterfactual intervention areas using comparison block groups in Flint; treatment diffusion was addressed by using comparison block groups from Detroit. The synthetic control method calibrated a set of weights to match precisely the intervention hot spots to counterfactuals from Flint and Detroit. Although basic trend analyses suggested declines in violent crime in the treatment areas, the synthetic controls raised questions about treatment effects. Specifically, the Flint comparison revealed an unexpected increase in aggravated assaults associated with the intervention; whereas, the Detroit comparison suggested a similar effect but also possible reduction in robberies. The overall conclusion is that the evaluation produced mixed findings regarding the effect of the intervention on violent crime. Inconsistent program effects may be attributable to incongruences between the program as implemented and the prescribed DDACTS model on which it was based. The findings also suggest the need for future research to investigate potential differential effects of directed patrol on specific types of violent crime. The synthetic control method provides a powerful means for counterfactual estimation in retrospective evaluations. (publisher abstract modified)