Using Space–Time Analysis to Evaluate Criminal Justice Programs: An Application to Stop-Question-Frisk Practices

Objectives: Effects of place-based criminal justice interventions extend across both space and time, yet methodological approaches for evaluating these programs often do not accommodate the spatiotemporal dimension of the data. This paper presents an example of a bivariate spatiotemporal Ripley’s K-function, which is increasingly employed in the field of epidemiology to analyze spatiotemporal event data. Advantages of this technique over the adapted Knox test are discussed. Methods: The study relies on x–y coordinates of the exact locations of stop-question-frisk (SQF) and crime incident events in New York City to assess the deterrent effect of SQFs on crime across space at a daily level. Results: The findings suggest that SQFs produce a modest reduction in crime, which extends over a three-day period. Diffusion of benefits is observed within 300 feet from the location of the SQF, but these effects decay as distance from the SQF increases. Conclusions: A bivariate spatiotemporal Ripley’s K-function is a promising approach to evaluating place-based crime prevention interventions, and may serve as a useful tool to guide program development and implementation in criminology.