Evidence-Based Policing Matrix

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Neighborhood – McGarrell et al. (2001) [Directed Patrol]

Study Reference:

McGarrell, E. F., Chermak, S., Weiss, A., & Wilson, J. (2001). Reducing firearms violence through directed police patrol. Criminology and Public Policy, 1, 119-148.

*This is one of two entries from this report. The other is "Neighborhood - McGarrell et al. (2001) [Targeted Offender Approach]".

Location in the Matrix; Methodological Rigor; Outcome:

Neighborhood; General; Proactive; Moderately Rigorous; No Evidence of Effect

What police practice or strategy was examined?

This study examines the use of a directed police patrol strategy to reduce firearm violence in Indianapolis. Implemented within two police beats in the east district of the city, the intervention involved the use of increased traffic enforcement to reduce crime, where officers focused on maximizing the number of vehicle stops for traffic violations such as speeding, rolling through stop signs, expired license tags, and inoperable tail lights. This was considered a general deterrence strategy, as it was anticipated that increased police presence and traffic stops would deter offenders and lead to seizures of illegal weapons and drugs.

How was the intervention evaluated?

The authors compared the targeted area to a two-beat comparison area identified as being the most similar available area in the city, as well as to city-wide crime trends. In one analysis, a 90-day intervention period for the treatment and control areas were compared with the same 90-day period of the previous year to control for seasonal effects. In a second analysis, the researchers developed time-series models to test whether changes observed during the intervention period were significantly different from pre- and post-intervention trends in violent crime, comparing the targeted and comparison areas. Firearm-crime related outcomes examined included homicide, aggravated assault with a gun, armed robbery, as well as a total gun crimes measure.

What were the key findings?

The intervention did not appear to have a significant effect on gun crime. Aggravated assaults with a gun and armed robberies increased in both the east district target areas and the comparison areas (though these trends did not significantly differ from each other). Additionally, time series analyses failed to identify any significant pre- to post-intervention change in gun crime in the targeted areas.

What were the implications for law enforcement?

This research suggests that a wide net approach to conducting traffic stops and enforcement may not be an optimal approach to reducing gun crime. Instead, police agencies may be better served by conducting more in-depth investigations targeted at specific offenders who are most likely to be carrying an illegal weapon. The authors also note that that - in light of the impact of traffic and pedestrian stops on racial and ethnic minorities and communities - such strategies should be implemented with respect and dignity, and in consultation with community members and leaders in targeted communities.

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