An ex post facto evaluation of the Philadelphia GunStat model

Abstract

In January of 2012, Philadelphia Mayor Michael Nutter outlined the crime fighting measures that his administration would pursue during his second term as mayor. Included was a plan to introduce a multi-agency crime reduction program, which Philadelphia Police Commissioner Charles Ramsey and District Attorney Seth Williams would co-chair, called GunStat. GunStat was described as a collaborative effort to reduce gun violence through (1) identifying locations with a high incidence of violent crime, (2) pinpointing violent offenders responsible for these crimes, (3) focusing on arresting and prosecuting these offenders for crimes committed at these places, and (4) enhanced monitoring of offenders on probation and parole who are living and/or offending within these locations. In effect, GunStat was designed to target the right people (prolific, violent known offenders) at the right places (hot spots of violent crime). This dissertation is an in-depth, ex post facto evaluation of Philadelphia’s GunStat model as implemented over two phases and two years. It involved both a quasi-experimental research design which employed propensity score matching methods to generate comparisons, and a process-evaluation where several themes, including program implementation, were explored. The results here suggest that GunStat did not reduce crime relative to comparison locations. However, the qualitative data highlighted the importance of informal inter-agency networks that were developed during the course of the intervention, and suggested that GunStat put future collaborations on a solid footing. The implications for criminal justice policy, theory and evaluation design are discussed.