A significant body of evidence exists that police are most effective at reducing crime when deployed to small, high crime areas known as hot spots. In the summer of 2010, the Philadelphia Police and researchers from Temple University’s Center for Security and Crime Science (housed in the Department of Criminal Justice), with support from the Bureau of Justice Assistance, set out to better understand the impact of different policing tactics deployed in hot spots. Three different tactics were tested problem oriented policing, offender focus policing and foot patrol.

The first step in the experiment was to identify the highest crime areas in Philadelphia using spatial analysis. We gave the Philadelphia Police Department (PPD) a map showing those hot spots and asked for their input in two important. One was in defining hot spot boundaries that were operationally sound and the other was in identifying which type of tactic they thought best suited the problems at that hot spot. For example, if there were a few people that were causing the problem then it made sense to apply offender-focused policing. If the problem was street robbery, then a problem-oriented policing approach to address the why that place was so amenable to street robbery would be appropriate. Regional Operations Commanders worked with District Captains to identify 27 areas suitable for foot patrol, 27 suitable for problem-solving, and 27 where police would focus enforcement on violent repeat offenders. The PPD returned a new map with 81 hot spots defined and the most appropriate tactic for each hot spot listed. We applied a random selection process so that 20 areas of each type were selected for additional police activity, and seven of each area type would receive the normal police response.

District officers in collaboration with members of the community and the support of personnel from police headquarters from the PPD2020 team conducted the problem-oriented policing tactic. Local initiatives to address the causes of violence varied across districts as problems were unique to each area.

Criminal intelligence officers and district personnel identified repeat violent offenders and they informed command staff at the district level. The role of focusing enforcement activities on the identified individuals generally fell to officers assigned to a unit out of the normal shift pattern in each district.

District Captains assigned foot patrol officers to each site and decided both the shift times and the operational tactics applied. Foot patrol officers usually (though not in one case) worked in pairs and were volunteers. The general pattern was two officers, for 8 hours a day, five days a week.

We employed repeated measures multilevel modeling using contrast coding to analyze the results because these types of models describe changes in an outcome measured at multiple time points for a given unit of analysis – ideal for this type of complex problem. We also controlled for trends over time and temperature (as violence is known to increase as it gets warmer).

We found that offender focus areas were successful in reducing all violent crimes by 42% compared to the equivalent control areas. These violent incidents included homicide, robbery, and assaults – both aggravated and misdemeanor. The offender focus sites were even more effective on violent felonies, reducing them by 50% compared to the equivalent control areas. Beyond the crime reduction, additional potential benefits of a targeted enforcement strategy are that it is less intrusive for law-abiding citizens because it avoids the wholesale increases in pedestrian and traffic stops that are so damaging to police community relations and that produce large numbers of arrests and flood the criminal justice system. Depending on implantation, the tactic may also increase the perception of the police as more procedurally just and improve community satisfaction with the police.

The foot patrol areas were not successful in reducing violence during the experimental period, nor were the problem-solving areas.

In sum, by focusing police efforts on the problem people associated with the problem places, police can achieve significant crime reductions while potentially avoiding negative community perceptions of their actions. However, we need additional research that more precisely measures what police officers do while in hot spots if we are to develop greater insight into why some crime reduction tactics are more successful than other ones.

More details are available in a research brief here for practitioners.

The full study is published here as: Groff, E. R., Ratcliffe, J. H., Haberman, C. P., Sorg, E. T., Joyce, N. M., & Taylor, R. B. (2015). Does What Police Do At Hot Spots Matter? The Philadelphia Policing Tactics Experiment. Criminology, 53(1), 23-53.