This study evaluated the effects of a 9‐month randomized controlled hot-spots field experiment on firearm assaults and robberies in St. Louis, Missouri.
Targeted policing has proven effective in reducing serious crime in areas where it is highly concentrated, but the enforcement mechanisms responsible for the success of so‐called hot-spots strategies remain poorly understood. In the strategy evaluated in the current study, directed patrols were increased in both treatment conditions, while the experimental protocol limited other enforcement activity in one of the treatment conditions and increased it in the other. The results from difference‐in‐difference regression analyses indicate that the intervention substantially reduced the incidence of non-domestic firearm assaults, with no evident crime displacement to surrounding areas, to times when the intervention was not active, or to non-firearm assaults. By contrast, the study found no effects of the intervention on firearm robberies. Less definitive results suggest that the certainty of arrests and occupied-vehicle checks accounted for the treatment effects on non-domestic firearm assaults. (publisher abstract modified)