ABSTRACT
In this chapter, the authors pool together the individual results to obtain a combined estimate of the impact of the laws. They explain the methodology for combining the individual results and present the pooled estimates. The authors discuss their interpretation of the findings. The immediate goal in each city-specific case study was to obtain an unbiased estimate of the policy's impact in a given area. No policy designed to prevent firearm violence is more popular than mandatory sentence enhancements for gun crimes. An increase in non-gun crimes and a decrease in gun offenses would be compatible with both a preventive effect model and a weapon substitution model. To estimate the combined impact of the laws, they pooled the results from the six cities. The pooled analysis for homicides provides exceptionally strong support for the preventive effect model. The pooled results lead to very different conclusions from the city-specific case studies.
