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Groups -- Cahill et al. (2008)

Study Reference:

Cahill, M., Coggeshall, M., Hayeslip D., Wolff, A., Lagerson, E., Scott, M., Davies, E., Roland, K., & Decker, S. (2008). Los Angeles, California. In Community Collaboratives Addressing Youth Gangs: Interim Findings From the Gang Reduction Program. Washington, D.C.: Urban Institute Justice Policy Center.

Location in the Matrix, Methodological Rigor; Outcome:

Groups; Focused; Proactive; Moderately Rigorous; Mixed effects

What police practice or strategy was examined?

OJJDP’s Gang Reduction Program (GRP) framework includes (1) primary prevention strategies focused on the reduction of community risk factors and increase protective factors, such as the provision of a one-stop service and resource center for health and social services; (2) secondary prevention strategies focused on prevention and support services for at-risk youth involving families, schools, community and faith-based agencies; (3) intervention strategies in which a multi-disciplinary team focused on aggressive outreach to gang-involved youth; (4) suppression strategies to target enforcement and prosecution and utilize graduated sanctions to remove the most dangerous gang-involved youth; and (5) reentry programs focused on facilitating successful reintegration into targeted communities after being incarcerated. Though the primary prevention strategies included in GRP targeted long-term changes, the main strategy used to target short-term crime reductions involved suppression activities conducted through the Community Law Enforcement and Recovery (CLEAR) program. The CLEAR program deployed gang officers to targeted areas to increase police presence and gang enforcement. CLEAR also involved a partnership with the District and City Attorney's Offices to implement vertical prosecution focused on gang members and gang-related cases.

How was the intervention evaluated?

The GRP evaluation in Los Angeles focused on three areas within the city: a target area, a comparison area with similar socioeconomic conditions and crime patterns to the target area, and a displacement area based on geographic proximity and similarity of criminogenic features to the target area. The evaluation measured crime to see if gang-related activity declined in quantity and seriousness of offense over the course of GRP implementation (from 2005 to 2008) using reported crime incidents, arrests, and calls for service records for all offense types. The evaluation team examined five crime-related outcome measures with monthly time-series analyses: calls, shots fired; calls, vandalism; incidents, serious violence; incidents, gang-related; and incidents, gang-related serious violence.

What were the key findings?

The program yielded statistically significant reductions within the target area. Total gang-related incidents fell by 19% in the target area, with a smaller non-significant reduction in the comparison area. Also reports of shots fired declined significantly by 40% in the target area, but also declined by 31% in the comparison area. Reductions in serious violent incidents and serious gang-related violence occurred in both the target and comparison areas and cannot be attributed to the program. The number of calls to report vandalism was unchanged in both the target and comparison areas. No evidence of displacement was found.

What were the implications for law enforcement?

Targeting gang-related crime with a comprehensive program like GRP can reduce some, but not all, categories of gang-related crime and does not adversely affect neighboring areas. However, given the weaker evaluation design, the result of this study should be taken with caution.

Where can I find more information about this intervention, similar types of intervention, or related studies?