Testing a promising homicide reduction strategy: Re-assessing the impact of the Indianapolis "pulling levers" intervention

Abstract

Since the publication of analyses suggesting the significant impact on youth homicide of the Boston "pulling levers" intervention, a series of studies of similar strategies have indicated promise in reducing homicide and gun assaults. One of these studies was an assessment of a pulling levers strategy in Indianapolis, where trend analyses indicated a significant reduction in homicide following the intervention, while six other similar Midwestern cities did not experience a significant decline in homicide. We re-assess the results of the Indianapolis study by disaggregating the offenses into gang- and non-gang homicides. Given that the pulling levers program focused on influencing gangs and networks of chronic offenders, the impact of the intervention should be more apparent for gang homicides than for non-gang homicides. Alternatively, should the impact be similar for non-gang homicides, then it is more likely that the downward trend would be caused by unmeasured external forces. Coefficient-difference tests relying on estimates obtained from autoregressive integrated moving average (ARIMA) time-series models indicate that gang homicides declined significantly more than did non-gang homicides following the Indianapolis intervention. These findings suggest 'something happened' to gang homicides that did not happen to non-gang homicides, which adds further support that the pulling levers initiative was the driving force behind the overall reduction in homicide in Indianapolis. © 2009 Springer Science+Business Media B.V.