Evidence-Based Policing Matrix
Micro Places – Phillips et al. (2016)
Study Reference:
Location in the Matrix; Methodological Rigor; Outcome:
Micro-places; Focused; Proactive; Moderately rigorous; No evidence of an effect
What police practice or strategy was examined?
This study examines the short-term use of Police Paramilitary Units (PPUs) to address criminal activity at drug and violent crime hot spots. PPUs are also known as special weapons and tactics (SWAT) teams. For two days during the summer of 2012, the Buffalo, New York, Police Department conducted 39 raids, which involved the execution of arrest warrants and home-raids at known drug houses. While the authors of this study were not involved in the planning of the intervention, it is assumed that (1) the locations of raids were high crime areas, and (2) the PPU implementation was the same throughout all raids (e.g., the number of officers, types of vehicles, etc.).
How was the intervention evaluated?
This study uses a post-hoc nonrandomized quasi-experimental design to examine the deterrent effects of the PPU raids using crime and arrest data. The authors employ a propensity score matching method in which each targeted place was matched with similar non-treated micro geographic places in Buffalo based on crime levels and demographic indicators. To avoid contamination between treated and non-treated locations, street units (the mid-points of street segments and intersections) within 2,000 feet of a raid were ineligible for matching. General deterrent effects were measured using data on calls for service and Part I crimes, while specific deterrence was measured using drug arrest data. This evaluation used data from 35 weeks before the two-day raid and for 35 weeks following.
What were the key findings?
Treated locations saw a significant 8% increase in calls for service following the raids relative to comparison locations and a significant increase in drug arrests. Both violent and nonviolent Part I crimes showed a slight decrease, but these were not statistically significant (even when all Part I crimes were combined). Further, the slight decrease in Part I crimes stopped after two weeks. These results suggest little to no evidence of a deterrent effect from PPU raids.
What were the implications for law enforcement?
Agencies looking to use PPU raids should not expect declines in crime at drug and violent hot spots, especially when raids are as brief as two days. Based on the findings of this study, PPU raids may also produce an increase in calls for service. However, this increase in calls for service might be attributable to residents being more inclined to report drug activity after the raids. While the null findings do not prove that PPU raids are ineffective in this context, agencies might consider other hot spot policing tactics, especially since PPUs might be viewed as too forceful by the public, ultimately harming police-community relations.
Where can I find more information about this intervention, similar types of intervention, or related studies?