title: The spillover effects of focused deterrence on gang violence.
abstract: BACKGROUND
  Focused deterrence strategies attempt to increase punishment risks faced by violent gangs through the development of new and creative ways of deploying traditional and non-traditional law enforcement tools. In addition to increasing the swiftness and certainty of sanctions, these strategies explicitly communicate incentives and disincentives to deter likely gang offenders from violent behavior.
  
  
  OBJECTIVE
  This study seeks to determine whether focused deterrence strategies generate spillover deterrent effects on the gun violence behaviors of vicariously treated gangs that were socially tied to directly treated violent gangs.
  
  
  METHODS
  A nonrandomized quasi-experimental design was used to evaluate the gun violence reduction effects of focused deterrence strategies on directly treated gangs and vicariously treated gangs. Propensity score matching techniques were used to identify balanced comparison gangs for the vicariously treated gangs. Growth curve regression models were used to analyze gun violence trends for treated gangs relative to comparison gangs.
  Quarterly counts of fatal and non-fatal shootings involving specific street gangs between 2006 and 2010 served as the units of analysis.
  
  
  METHODS
  Key outcome measures included quarterly shootings committed by specific gangs, shooting victimizations suffered by specific gangs, and the total number of shootings involving specific gangs.
  
  
  RESULTS
  The focused deterrence strategy was associated with statistically significant reductions in total shootings by directly treated gangs and vicariously treated gangs.
  
  
  CONCLUSIONS
  Our study finds that vicariously treated gangs were deterred by the treatment experiences of their rivals and allies. This suggests that focused deterrence strategies can generate spillover crime reduction effects to gangs that are socially connected to directly treated gangs.
authors.affiliation: Rutgers University, Newark, NJ, USA.
authors.forename: Anthony A
authors.initials: AA
authors.lastname: Braga
authors.forename: Robert
authors.initials: R
authors.lastname: Apel
authors.forename: Brandon C
authors.initials: BC
authors.lastname: Welsh
mesh_terms: D001900:Boston / Q000453:epidemiology; D003415:Crime / Q000517:prevention & control*; D003416:Criminal Law / Q000379:methods; D005389:Firearms; D006801:Humans; D035846:Law Enforcement / Q000379:methods; D016495:Police; D014754:Violence / Q000517:prevention & control*; D014948:Wounds, Gunshot / Q000453:epidemiology / Q000401:mortality
keywords: deterrence; difference-in-differences; diffusion of benefits; gangs; quasi-experimentation