NCJ Number
209937
Journal
Crime Prevention and Community Safety: An International Journal Volume: 7 Issue: 2 Dated: 2005 Pages: 7-13
Date Published
2005
Length
7 pages
Annotation
This article identifies major differences between an evaluation of area-based crime-reduction intervention by comparing areas and an evaluation of treatment effectiveness with a classic randomized controlled trial (RCT).
Abstract
Misleading findings will result if a comparative area-based crime-reduction trial is viewed as an RCT. Evaluations that compare areas, one with an intervention and one without, are neither randomized nor controlled; and the crime events counted are correlated rather than statistically independent. Statistical biases will result because of the lack of equivalence between areas at the outset. Obtaining reliable evidence for the effectiveness of a crime-reduction measure requires the random assignment of a number of areas to receive the intervention or be kept unchanged. The data must then be analyzed with "area" as the unit of analysis. Further, trials should be designed to determine the number and size of participating areas, so as to obtain adequate information at minimum cost. This article compares valid evaluations of crime-reduction interventions with the method of health care research, which ensures the use of the correct unit of observation and analysis, incorporates randomization, and relies on statistical independence between observations. 3 tables, 2 figures, and 6 references