By Nola Joyce, Deputy Commissioner, Philadelphia Police Department, Philadelphia, Pennsylvania; and Jerry Ratcliffe, Professor, Temple University, Philadelphia, Pennsylvania
The IACP Research Advisory Committee is proud to offer the monthly “Research in Brief” column. This column will feature evidence-based research summaries that highlight actionable recommendations for Police Chief magazine readers to consider within their own agencies. The goal of the column is to feature research that is innovative, credible, and relevant to a diverse law enforcement audience.
major research collaboration between the Philadelphia, Pennsylvania, Police Department and researchers in the Department of Criminal Justice at Temple University1 may spark a revision of a long-held view of police foot patrols.
Since the 1980s, many police and criminology researchers have held the opinion that police foot patrols can improve community perception of the police and reduce fear of crime while not preventing actual crime. Results from the Philadelphia Foot Patrol Experiment suggest that a more positive view of intelligence-led targeting of foot patrol officers may be warranted. Police and academic researchers worked together to plan the Philadelphia Foot Patrol Experiment as a randomized controlled trial, using about 250 officers to patrol 60 violent crime locations during summer 2009. In summary, after three months and relative to the comparison areas,
- violent crime in the target areas decreased 23 percent,
- drug-related incident detections increased 15 percent in the target areas,
- pedestrian stops conducted by police increased 64 percent in the target areas,
- vehicle stops increased 7 percent in the target areas, and
- arrests increased 13 percent in the target areas.
The reduction in violence indicates the foot patrols prevented 53 violent crimes during the summer.
During early 2009, violent crime reports were drawn from the incident database of the Philadelphia Police Department for 2006, 2007, and 2008. Violent crime here is defined as homicide, aggravated assault, and robberies not occurring indoors. Incidents were weighted so crimes from 2008 counted 1.0, crimes from 2007 counted 0.5, and crimes from 2006 counted 0.25. In this way, more recent events had greater relevance in the creation of the target locations for 2009, but area values could still retain a portion of the long-term hotspot component.
These weighted values were aggregated and summed to spatial units, called Thiessen polygons, centered on every street intersection in the city. This allowed the researchers to measure the city’s crime centered on the nearest street corner to the crime incident. This resulted in a map of violent crime down to the nearest street corner. The top 5 percent of corners accounted for 39 percent of robberies, 42 percent of aggravated assaults, and 33 percent of homicides in 2008.
The police department identified 129 potential foot patrol areas from which 120 were selected for the experiment. Each area contained about 15 street intersections and 1.2 miles of roads. The foot beats were ranked by the weighted volume of violent crime and were paired with a foot beat of a similar crime rate. One from each pair was randomly selected to be a target beat, while the other became a control (or comparison) area.
Officers generally patrolled in pairs with two pairs assigned to each foot patrol. They worked from Tuesday morning to Saturday night in two shifts: 10:00 a.m. to 6:00 p.m. and 6:00 p.m. to 2:00 a.m. All patrol officers were provided with an initial criminal intelligence brief on their foot patrol areas by the criminal intelligence unit, as well as whatever information they gleaned from their initial orientations. Some officers engaged in considerable community-oriented work, speaking to community members and visiting child care centers and juvenile hangouts, while others were more crime oriented, stopping vehicles and conducting field interviews of pedestrians.
What We Learned
The researchers employed both an analysis of change scores and a linear regression model in which the crime value of the operational period served as the dependent variable and the preoperation crime level served as a covariate. The linear regression model outcomes were examined in phases based on percentile levels or preintervention violence. To examine the issue of displacement, they also used Bowers and Johnson’s weighted displacement quotient
We found the violent crime hotspots experienced a reduction in violence of 90 offenses, with a net effect of 53 offenses once displacement is considered, outperforming equivalent control areas by 22 percent. However, the benefits were achieved only in areas with a threshold level of preintervention violence. The lack of a significant reduction in the less-violent crime hotspots suggests that foot patrols are not a silver bullet to the problem of violence prevention. They may be measurably effective only in the highest crime areas. The relative lack of violent crime in other areas may warrant a more cost-effective approach to crime reduction, such as problem-oriented policing.
We did discover some modest displacement that was less than the direct benefits achieved in the target areas. Ninety crimes were prevented in the target area, offset by a 37-crime increase occurring in the displacement areas immediately surrounding target areas.
This scholar-practitioner collaboration between Temple University and the Philadelphia Police Department has received much attention nationwide for its success, including a published article in Criminology, the premier academic journal in the criminology field, and replications from other police departments. The methodology and process for implementation for this research partnership has been well documented and can provide a valuable template for the readers of Police Chief who are interested in this evidence-based and effective approach to foot patrol. ■
- View the complete study for a fuller understanding of the nature and the impact of police foot patrols: http://www.temple.edu/cj/FootPatrolProject (accessed April 9, 2012).
- Compare your agency’s use of foot patrol with the Philadelphia, Pennsylvania, Police Department. What role does foot patrol play in your community policing efforts?
|Deputy Commissioner Joyce is a member of the IACP Research Advisory Committee.|
|Interested in submitting a research summary for Research in Brief? Email email@example.com.|
1The Temple University researchers were Jerry Ratcliffe, Travis Taniguchi, Elizabeth Groff, and Jennifer Wood.
Please cite as:
Nola Joyce and Jerry Ratcliffe, "Foot Patrols Responsible for Marked Decline in Violent Crime," Research in Brief, The Police Chief 79 (May 2012): 10.