Evidence-Based Policing Matrix
Individuals – Martin & Sherman (1986)
Study Reference:
Location in the Matrix; Methodological Rigor; Outcome:
Individuals; Focused; Reactive; Rigorous; Effective
What police practice or strategy was examined?
The study examines the effectiveness of the Repeat Offender Program (ROP), a specialized police unit established in Washington, DC in the 1980s. Its objective was the identification and apprehension of two types of active recidivists: those already wanted on one or more warrants who could be arrested on sight and those believed to be criminally active but not currently wanted. The former were called “warrant targets”; the latter came to be called “ROP-initiated” targets. To arrest persons who were not wanted, ROP officers had to develop evidence about a specific crime in which they participated. This involved a variety of vice and investigative activities such as buy-and-busts, cultivating informants and investigating their “tips,” surveillance of targets, and linking stolen property found in the possession of a target back to its rightful owner.
How was the intervention evaluated?
An experiment was conducted to determine whether persons selected as “repeat offenders” by ROP were more likely to be arrested because of ROP’s efforts than they would be in its absence. The experimental design required ROP officers to identify their constantly changing pool of targets, to pair any two of the same target type (warrant targets or ROP-initiated targets), and to randomly assign one target from each pair to the experimental condition (investigated by ROP) or the control condition (not investigated by ROP). Experimental targets were investigated by a ROP squad of officers for a seven-day period; control targets were off limits to ROP officers but could be arrested by any other police officer. The experiment lasted 26 weeks, during which time work on 212 pairs of randomly assigned targets was completed.
What were the key findings?
The experimental results clearly showed that ROP increased the likelihood of arrest of targeted repeat offenders. Of the 212 experimental subjects, ROP arrested 106 (50%). In contrast, only eight control subjects not assigned to ROP (4%) were arrested by officers in other units. Strong differences in arrest rates were found for both warrant and ROP-initiated targets. Fifty-five percent of warrant targets eligible for ROP arrests were arrested by ROP, a sharp contrast to the 9% of warrant targets eligible for non-ROP arrests that were arrested by non-ROP officers.
What were the implications for law enforcement?
By most measures used to assess ROP, that unit appears to have succeeded in its goals of selecting, arresting, and contributing to the incarceration of repeat offenders. A cost to consider is that ROP officers’ arrest productivity was cut in half (ROP officers in the six-month study period made an adjusted average of 5.7 arrests per officer, while comparison officers made an adjusted average of 12.4 arrests). However, this cost appears to have been offset by the greater seriousness of the current and prior offenses of ROP arrestees. The study concludes that the creation of selective apprehension units provides a promising new strategy for major urban police departments. (But note that the study was not able to show whether the apprehension of these offenders reduced the jurisdiction’s crime rate.)
Where can I find more information about this intervention, similar types of intervention, or related studies?