This analysis of block-level deterrent effects of uniformed police raids of crack houses in Kansas City, Missouri, suggested that such raids produced qualified deterrence.
Between November 1991 and May 1992, the Kansas City Police Department implemented a randomized controlled trial in raiding crack houses. The research design focused on outcome measures, a sample of eligible cases drawn from a continuous pipeline of undercover investigations, a procedure for screening and random assignment, and an analytic plan made in advance and applied continuously as the study progressed. Court-authorized raids were legally possible on 207 blocks with at least five calls for police service in the preceding 30 days. Raids were randomly assigned to 104 locations and were conducted at 98 of those sites; the other 109 locations were left alone. Experimental blocks in relation to control blocks showed reductions in both calls for police service and offense reports, but these effects were quite small and decayed in 2 weeks. Raids in which arrests were made had no consistently different impact from raids in which no arrests were made. Raids had more effect on calls for police service in the winter than in the spring, but little seasonal or period differences in effects of raids on offense reports were observed. The authors conclude alternative police methods may be more cost-effective than raids in harm reduction for crack houses. 29 references, 7 footnotes, 3 tables, and 3 figures