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Fifteen Minutes per Day Keeps the Violence Away: A Crossover Randomised Controlled Trial on the Impact of Foot Patrols on Serious Violence in Large Hot Spot Areas

NCJ Number
Cambridge Journal of Evidence-Based Policing Volume: 5 Dated: 2021 Pages: 93–118
Date Published
26 pages

This study of the impact of police foot patrols found that such patrols can prevent serious violent crime.


This study concluded that even minimal amounts of foot patrol can prevent serious violent crime across a large area, and that repeated patrols over several days help even more. The findings suggest that uniformed officers need to patrol hot spots for short amounts of times on consecutive days. The authors tracked daily official crime reports in a sample of 21 high-crime Bedfordshire (UK) Lower-layer Super Output areas (LSOAs) and measured time spent by two-person police foot patrols in those areas with daily GPS data from handheld devices given to officers working on overtime. The authors also counted proactively initiated arrests. They used a crossover randomised controlled trial on the 21 “hot spot” LSOAs, each of which was randomly assigned daily to be either in a treatment condition of 15-min of patrol or a control condition of no patrol for each of 90 days. The authors used an intention-to-treat framework to analyse the impact of patrols on the outcome measures overall. The study found that on treatment days the hot spots had 44% lower Cambridge crime harm index scores from serious violence than on control days, as well as 40% fewer incidents across all public crimes against personal victims. Statistically significant differences in lower prevalence, counts and harm of both non-domestic violent crime and robbery and other non-domestic crimes against personal victims were also found. The authors found no evidence of either displacement of serious crime into a 100-m buffer zone, nor any evidence of residual deterrence on no-patrol days following patrol days. The authors did find evidence of a cumulative effect: the largest differences in crime harm on control days were found in treatment days that came after 3 days of consecutive patrol in the same LSOA. (Published Abstract Provided)

Date Published: January 1, 2021