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Micro Places – Ratcliffe et al. (2011)

Study Reference:

Ratcliffe, J., Taniguchi, T., Groff, E. R., Wood, J. D. (2011). The Philadelphia Foot Patrol Experiment: A randomized controlled trial of police patrol effectiveness in violent crime hotspots. Criminology, 49(3), 795-831.

Location in the Matrix; Methodological Rigor; Outcome:

Micro places; General; Proactive; Very Rigorous; Effective

What police practice or strategy was examined?

This study tests the impact of increased foot patrol on reported violent crime. It reports on the efforts of over 200 foot patrol officers in Philadelphia during the summer of 2009. Each target area was patrolled by two pairs of new officers. After a 1-week orientation and  an initial period with an experienced officer, the pairs patrolled their hot spots for a 12 week treatment period. The officer pairs worked either a morning (10 a.m. to 6 p.m.) or an evening shift (6 p.m. to 2 a.m.) Tuesday through Saturday. The pairs alternated morning and evening shifts every other week.

How was the intervention evaluated?

Hot spots were identified using violent crime incident data.  A randomized experimental methodology was used with 30 hot spots randomly allocated to the foot patrol treatment and 30 assigned to a control group that received no special police attention.. Violent crime was the main outcome of interest and was recorded for the three months prior to the intervention and the 12  week intervention.  The authors also used catchment areas to assess displacement.

What were the key findings?

Results identified a significant reduction in violent crime in the treatment areas after 12 weeks. Even after accounting for natural regression to the mean, target areas in the top 40% on pre‐treatment violent crime counts had significantly less violent crime during the intervention period. In total, target areas outperformed the control sites by 23 percent, resulting in a total net effect (once displacement was considered) of 53 violent crimes prevented. Significant displacement effects were found, but displacement was far less than overall crime prevented.

What were the implications for law enforcement?

The authors suggest that targeted foot patrols in violent crime hot spots can significantly reduce violent crime levels as long as a threshold level of violence exists initially, and that intensive foot patrol efforts in violent hot spots may achieve deterrence at a micro‐spatial level, primarily by increasing the certainty of disruption, apprehension, and arrest.

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