Study
The Philadelphia Low-Intensity Community Supervision Experiment conducted by Barnes and colleagues (2010) used a randomized trial to test the effects of lowering the intensity of community supervision with low-risk individuals. The field experiment took place from 2007 to 2008 in the western and northeastern regions of Philadelphia, Pa.
Data on a total of 12,233 probation cases involving 7,830 different individuals under active supervision was extracted from the case management database run by the Adult Probation and Parole Department (APPD). The data was linked to court history data from the Court of Common Pleas Case Management System. Eligible persons were identified with the random forests model (described in the Program Description). Cases were eligible for random assignment only when more than 50 percent of the votes forecasted an absence of serious offenses.
This narrowed the data down to 2,859 cases that were screened for exclusionary criteria before random assignment. People were ineligible if they were scheduled to end supervision within 60 days of the start of the experiment, they were ordered by court to a specialized unit, they were supervised in an existing low-risk caseload, or they were in potential direct violation of their sentence owing to an arrest occurring after the start of their supervision. This left a total sample size of 1,559 participants who were randomly assigned to either low-intensity community supervision (experimental treatment group) or standard regional supervision (control group).
In the western APPD region, 400 individuals were assigned to the low-risk caseload and 401 to the control group. In the northeastern APPD region, 400 individuals were assigned to the low-risk caseload and 358 to the control group. The experimental treatment group was 66.5 percent male, 48.0 percent African American, and 42.8 percent white, with an average age of 40.8 years. The control group was 67.6 percent male, 48.4 percent African American, 38.9 percent white, and with an average age of 40.6 years. There were no significant differences between groups on demographic variables.
The experiment was a single-blind study, because the probation officers of the people in the low-intensity supervision group were informed of their involvement in the experiment, whereas probation officers of the control group were not informed of their inclusion. Once the experiment began, the number of contacts with probation officers experienced by the experimental group was reduced by about 45 percent, while the control group had almost the exact same amount of contact as they had encountered during the previous year.
Recidivism was measured as any charges that occurred after the start of the experiment. Recidivism data was collected from court records and was limited to offenses that were dealt with by the Philadelphia courts (offenses that took place outside the city limits were excluded from the analysis). The data included information on time from release to first rearrest, reincarceration, frequency of offending, and seriousness of offending. Serious offenses were defined as murder, attempted murder, aggravated assault, or sex crimes. The period of outcome measurement was October 1, 2007, through Sept. 30, 2008.
The study used intent-to-treat analysis, which means all participants were retained in the treatment group even if they were not permitted to participate in the low-intensity supervision treatment. Approximately 17.8 percent of the experimental participants were retained in the analysis of the treatment group, even though they did not receive low-intensity supervision.
