RT Article T1 The Relative Incident Rate Ratio Effect Size for Count-Based Impact Evaluations: When an Odds Ratio is Not an Odds Ratio JF Journal of quantitative criminology VO 38 IS 2 SP 323 OP 341 A1 Wilson, David B. LA English YR 2022 UL https://krimdok.uni-tuebingen.de/Record/1884549020 AB Area-based prevention studies often produce results that can be represented in a 2-by-2 table of counts. For example, a table may show the crime counts during a 12-month period prior to the intervention compared to a 12-month period during the intervention for a treatment and control area or areas. Studies of this type have used either Cohen’s d or the odds ratio as an effect size index. The former is unsuitable and the latter is a misnomer when used on data of this type. Based on the quasi-Poisson regression model, an incident rate ratio and relative incident rate ratio effect size and associated overdispersion parameter are developed and advocated as the preferred effect size for count-based outcomes in impact evaluations and meta-analyses of such studies. K1 odds ratio K1 Cohen’s d K1 Meta-analysis K1 Counts K1 Poisson K1 Incident rate ratio K1 effect size DO 10.1007/s10940-021-09494-w