The Effects of Sanction Intensity on Criminal Conduct - JDAI Helpdesk

the proportions <strong>of</strong> false positives and false negatives expected in the final model to be
operationally acceptable.
<strong>The</strong> proportion <strong>of</strong> false positives (<strong>of</strong>fenders erroneously
identified as low risk) was set at 5 per cent, and the proportion <strong>of</strong> false negatives
(<strong>of</strong>fenders erroneously identified as high risk) was 20 per cent. A higher false negative
rate was accepted given the lesser public safety concerns around this type <strong>of</strong> error.
Experimental design
Selection <strong>of</strong> Cases
APPD selected the West and Northeast regional supervision units as the sites from
which experimental participants would be drawn. All cases active on probation in these
two units on July 27, 2007 were extracted. <strong>The</strong> random forests model was applied to
each case to produce an individual risk assessment (some probationers had multiple
cases) in the form <strong>of</strong> a ‘reliability score.’ <strong>The</strong> reliability score is a number between 0 and
1. Cases with a reliability score above 0.5 were designated as low risk. From this
assessment, 2,859 <strong>of</strong>fenders were serving probation terms for low-risk <strong>of</strong>fenses. <strong>The</strong>y
were pre-screened for eligibility for the experiment. Low-risk cases were excluded from
the random assignment pool if any one <strong>of</strong> the following factors made them ineligible for
low-intensity supervision:
<strong>The</strong> case was due to expire within thirty days <strong>of</strong> the extraction date.
<strong>The</strong> <strong>of</strong>fender was placed under the supervision <strong>of</strong> a specialized unit by court order
after the extraction date.
<strong>The</strong> <strong>of</strong>fender was in an existing low-risk caseload. 4
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