Evidence-Based Policing Matrix
Groups – Corsaro & Engel (2015)
Study Reference:
Location in the Matrix; Methodological Rigor; Outcome:
Groups; Focused; Highly proactive; Moderately rigorous; Effective
What police practice or strategy was examined?
This study evaluated a focused deterrence group violence reduction strategy (GVRS) implemented in New Orleans (LA) between 2012-2014. The intervention focused on a small number of violent gangs responsible for the majority of the city’s homicide incidents. The New Orleans Police Department (NOPD), in collaboration with ATF agents, researchers, and members of outside police departments, identified potential street gangs through an analysis of gang members, gang geography, social networks, and participation in violence. Once identified, the NOPD conducted offender notification sessions to inform the gangs that continued violence would result in heightened attention and punishment. These sessions involved call-ins of potential gang members that were currently incarcerated, on probation, or on parole. Over the course of five separate sessions, 158 individuals attended these meetings. These individuals were asked to pass on the message that any subsequent murders or shootings would result in targeted law enforcement toward the entire gang. Targeted gang members were also provided with access to social services in an attempt to provide them with resources to escape gang life.
How was the intervention evaluated?
The intervention was evaluated using a quasi-experimental design comparing homicide rates in New Orleans to those in 14 other cities with similar pre-existing homicide rates and trends between 2008-2013. Researchers also compared trends in gang-related violent crime (total homicides, firearm-related homicides, firearm assaults, gang member involved homicides) from 2008-2014 to those of crimes that would likely not be affected by the intervention (overall violence, overall property crime, non-gang member involved homicides). This second analysis only compared trends in these outcomes within New Orleans and employed an expanded pre-intervention period (January 2008-October 2012) and post-intervention period (November 2012-March 2014).
What were the key findings?
The GVRS intervention was associated with a significant homicide rate decline of approximately 17% during the post-intervention period compared to the rates of the 14 comparison cities. The intervention was also associated with significant postintervention reductions in gang member involved homicides (approximately 32%), firearm homicides (approximately 16%), and firearm assaults (approximately 16%) in New Orleans, compared to no significant changes in non-gang member involved homicides, overall violence, or overall property crime in the city.
What were the implications for law enforcement?
The authors suggest that focused deterrence interventions hold promise for addressing issues of persistent urban violence, particularly when combined with proper organizational support, multi-agency cooperation, and in-depth problem analysis.
Where can I find more information about this intervention, similar types of intervention, or related studies?