Estimating Intervention Effects in Varying Risk Settings: Do Police Raids Reduce Illegal Drug Dealing at Nuisance Bars?*

This paper investigates the effectiveness of police raids in reducing drug dealing in and around nuisance bars. We examine effects of both dosage (number of raids) and duration (months) of the intervention, as well as the conditioning effects of land use and population characteristics in shaping the underlying risk levels of drug dealing in the target and surrounding areas. Results indicate that the police intervention suppresses levels of drug dealing during periods of active enforcement, but the effects largely disappear when the intervention is withdrawn. Also, the effects of the intervention are mediated by risk characteristics in target and surrounding areas. Target areas characterized by higher levels of risk are more resistant to intervention effects than those with lower levels of risk. Risk factors in nearby areas are also significant. Bars with high levels of risk arising from land uses in surrounding areas are easier to treat, while bars with high levels of population‐based risk in surrounding areas are harder to treat.