Patrol evaluation research: a multiple-baseline analysis of saturation police patrolling during day and night hours.

The effects of a carefully monitored and increased police patrol on the report of crime were examined in four patrol zones. Overall patrol movement was increased to four times normal levels and slow patrol movement (under 20 mph) to around 30 times normal levels for 10 days. The patrol was active in two zones between 9:00 a.m. and 5:00 p.m. and in the other two zones between 7:00 p.m. and 3:00 a.m. A multiple-baseline design and time-series statistical analyses showed statistically reliable changes in reported levels of Part I crime (such as robbery, burglary, and aggravated assault) during both night patrols, but not in the day patrols. In both night-patrol zones, there were also reliable increases from saturation patrol to postsaturation patrol in report of Part I crime after the night patrol was terminated. Neither of the day patrols showed significant crime report changes on termination. Despite statistically reliable decreases in report of crime during nighttime hours, the value of saturation patrolling as a crime-prevention technique was questioned on cost/benefit grounds.