SPI Findings

Bivariate analysis and interrupted time series analysis to assess the impact of the focused deterrence pulling levers strategy.

40% reduction in homicide.

19% reduction in gun-related aggravated assaults.

The sites, with buffer zones, were randomly assigned as either treatment or control areas: five for saturation patrol; five for network-based intervention (NBI); and six control areas. Comparable pre- and post-intervention periods were established to measure results and changes over time.

• Saturation patrol resulted in fewer high priority calls for service
• Saturation patrol resulted in fewer crimes, although the impact was modest
• Network-based interventions resulted in fewer high priority calls for service during the first year of implementation but increases in the second year. 
• Crime in network-based intervention experienced few changes in overall crime, and violent crime in these MHSs increased relative to control areas

Interrupted time-series analysis, which assesses whether the interventions in target areas had an effect on crime while controlling for previous trends. (Research evaluation is ongoing.)

22.6% reduction in homicides per month in the target division.

5.2% reduction in gun crimes per month in each reporting district of the target division.

The evaluation examined two major indicators for implementation (dosage) and outcomes (crime reduction).

• Study findings showed that LASER resulted in significant division-wide reductions in Part I crimes, gun crimes, and robberies. 
• LASER was credited with double digit reductions in homicides and victims shot in four divisions that accounted for 48% of the city’s violent gun crimes.

Interrupted time series research design complemented by a process evaluation. 

• From 2014 to 2017, crimes decreased by 17% from 5,694 to 4,723. The largest decreases were in car breaks (34.7%), burglary (25.5%), and aggravated assaults (24.6%).
• Decentralization of the Crime Analysis and Intelligence Unit (CAIU) has had a significantly positive impact on the interaction between analysts, officers and supervisors, literally creating a direct relationship between analysts and officers in the field.
• CAIU decentralization has increased information sharing across CAIU, officers and supervisors.

Researchers wanted to evaluate the effectiveness of ShotSpotter’s technology in comparison to currently implemented strategies. To do so, researchers collected and evaluated data on cases where (1) ShotSpotter was the only basis for the call, (2) cases where ShotSpotter did not detect, and the response is only a call for service (CFS) and (3) ShotSpotter and a CFS both occurred for the incident.  Additionally, researchers collected data on the number of shooting reports resulting from ShotSpotter versus that didn’t come from ShotSpotter, time to response (ShotSpotter vs non-ShotSpotter) and lastly, the number of National Integrate Ballistic Information Network hits were collected as a result of ShotSpotter. Data was gathered from 16 months prior to the implementation of ShotSpotter and compared to data collected 16 months post implementation.

• The implementation of ShotSpotter significantly increased the number of NIBIN hits.
• ShotSpotter was often instantaneous, alerting agencies of a gunshot within seconds.
• Implementation of ShotSpotter and gunshot detection technology highlights the number of shots fired that do not get reported to police.

A quasi-experimental design was used which included a one sample pre-post design to examine agency perceptions of use of crime analytics. The evaluation of crime reduction was comprised of a simple time series assessment and emerging pre-post comparisons in micro-level target areas.

• Pre and post knowledge tests of analysts surrounding formal training sessions showed a 25 to 53 percent improvement in testing scores.
• Further, an approximated before and after assessment of administrators found that analytical work products went from being used never or only occasionally, to now being used about 1 to 2 times per week on average.

To understand the impact that Miami’s Real Time Crime Center (MRTCC) had on police practices, researchers utilized a mixed-methods study design consisting of three parts. First, researchers utilized a qualitative survey distributed to the frequent users of the MRTCC technologies to understand the role that they played in various MPD assignments and gauge officer perceptions of its benefits. Next, researchers designed a network analysis of violent crime case components to visualize and determine how MRTCC technologies have become integrated into case processing within the Miami Police Department. This allowed for researchers to evaluate how MPD utilizes and integrates MRTCC products within their case processing. Lastly, a quasi-experiment with relevant controls was conducted to understand the impact of MRTCC technologies on clearance rates and the time it takes for the agency to clear a case.

• Users of the MRTCC technologies had a positive perception of the technology and found them to be easily accessible and useful to their daily work.
• Most respondents believed that MRTCC technologies had improved the identification and documentation of evidence, improved the ability to clear cases, and reduced the time to clear cases.
• Users conveyed that the MRTCC platform could be improved by expanding the technologies, particularly CCTV, to cover more operational areas 24 hours a day, and by allowing direct use of some technologies by detectives and commanders.
• The use of MRTCC technologies has become fully integrated into the processing of cases.
• Use of MRTCC technologies has significantly improved the ability to clear violent crime cases but has not shortened the amount of time to clear cases.

Randomized controlled trial of 252 officers assigned a BWC and 252 officers without a BWC. The experiment used a difference-in-differences approach for the analysis between the two groups. 

• Those who wore BWCs conducted fewer subject stops and were less likely to receive a complaint than officers that did not receive cameras.
• However, BWCs had no effect on whether officers engaged in use of force during the study period.

Pre-intervention, intervention, and post-intervention analysis in target and control areas.

During intervention, 19% reduction in violent crime at the neighborhood-level and 36% reduction in violent crime in high-risk areas.

13 weeks following the intervention, 41% violent crime reduction at the neighborhood level and 56% reduction in the high-risk areas.