Center for Problem-Oriented Policing

POP Center Responses Gunshot Detection Appendix A

Appendix A: Studies Exploring Acoustic Gunshot Detection Systems’ Efficacy to Reduce Gun Violence

City	Years and Type	Targeted Offense	How Effective	Research Design	Studies
St. Louis, Missouri	2006–2009 ShotSpotter	Part I Gun Offenses	No significant effects. Reductions and increases occurred randomly in both experimental and control sites	Interrupted time-series	Mares and Blackburn (2012)
Philadelphia, Pennsylvania	2015–2016 SENTRI sensors with CCTV	Gunshots calls for service	259% increase in gunshot notifications, but no significant increase in founded incidents	Block randomized controlled experiment, multi-level difference-in-difference	Ratcliffe et al. (2018)
Denver, Colorado	2008–2016 ShotSpotter	Gun crime calls for service and Part I crimes	No significant changes in crime levels or calls for service	Quasi-experimental interrupted time-series	Lawrence, La Vigne, and Thompson (2019)
Milwaukee, Wisconsin	2008–2016 ShotSpotter	Gun crime calls for service and Part I crimes	Significant increases in gun crime calls for service; no significant reductions in reported gun crimes	Quasi experimental interrupted time-series	Lawrence, La Vigne, and Thompson (2019)
Richmond, California	2006–2015 ShotSpotter	Gun crime calls for service and Part I crimes	Significant increases in gun crime calls for service; no significant reductions in most restrictive models but some in less restrictive models (around 30%)	Quasi experimental interrupted time- series	Lawrence, La Vigne, and Thompson (2019)
St. Louis, Missouri	2005–2018 ShotSpotter	Calls for service for gunfire and gun violence	Significant reductions in gunfire calls for service; some reduction in gun violence initially but none significant	Quasi-experimental multi-level difference-in-difference	Mares and Blackburn (2021)
68 Metropolitan Counties	1999–2016 ShotSpotter	Gun homicides, gun arrests, homicide arrests	No significant reductions in any metrics	Cross-sectional time series analysis	Doucette et al. (2021)
Wilmington, Delaware	2014–2020 ShotSpotter/CCTV integration	Homicides and shootings	No significant reductions	Interrupted time-series analysis	Vovak et al. (2021)
Cincinnati, Ohio	2015–2020 ShotSpotter	Calls for service shots fired and reported Gun assaults	Significant reductions (45% in shots fired and 46% in gun assaults)	Block matched quasi-experimental multi-level difference-in-difference	Mares (2021a)