Police evaluation research: an experimental and cost-benefit analysis of a helicopter patrol in a high crime area.

Greene et al. (1978) asked if a daytime helicopter patrol could stop home break-ins.

They used an ABAB reversal design. Helicopter on, off, on, off. Each phase lasted several weeks.

The site was a high-crime neighborhood. Patrol cars served as the baseline.

When the helicopter flew, burglaries dropped. When it stopped, break-ins rose again.

The money saved from fewer thefts was larger than the extra cost of flight time.

The simple reversal chart made the effect easy to see.

Bernal et al. (1980) extended the same idea to new areas. They found the helicopter only helped in crowded blocks. Low-density streets saw no change.

Lowe et al. (1977) tested ground saturation patrol. Night shifts cut crime, day shifts did nothing. The 1978 helicopter day shift worked, so aircraft patrol beats car patrol during daylight.

Malagodi et al. (1975) tried a home-burglary car patrol and saw no effect. The helicopter success updates that earlier failure.

You can test large-scale safety programs with single-case logic. Reversal and multiple-baseline designs speak to city managers who need clear graphs and cost numbers. When you consult on community safety, push for density checks first. A helicopter, bike squad, or extra officer hours may only pay off in tightly packed blocks. Run a short ABAB pilot before the city writes a big check.