The effect of target, catchment, and comparison site operationalization on CCTV impact evaluations: methodological considerations from a case study

Abstract

Objectives: To examine the extent to which different operationalizations of target, displacement, and comparison sites affect the interpretation of a CCTV impact evaluation. Methods: Different operationalizations are used to examine change in property and violent crime before and after CCTV was introduced in a residential neighbourhood in Malmö, Sweden, using paired t tests, odds ratio effect sizes and weighted displacement quotients. Results: Despite most results being non-significant as a result of low statistical power, different operationalizations appear to produce varying results. This issue is most prominent for target sites and property crime while it is less so for catchment and comparison sites, and violent crime outcomes. Conclusion: Valid operationalizations of research areas are highly important for CCTV impact evaluations and may affect the study outcome. Future research with access to larger data sets is encouraged to elaborate on these findings and further analyse the impact of measurement choices on experimental outcomes.