Risk, Race, & Recidivism: Predictive Bias and Disparate Impact

Abstract

One way to unwind mass incarceration without compromising public safety is to use risk assessment instruments in sentencing and corrections. Although these instruments figure prominently in current reforms, critics argue that benefits in crime control will be offset by an adverse effect on racial minorities. Based on a sample of 34,794 federal offenders, we examine the relationships among race, risk assessment (the Post Conviction Risk Assessment [PCRA]), and future arrest. First, application of well-established principles of psychological science revealed little evidence of test bias for the PCRA — the instrument strongly predicts arrest for both Black and White offenders and a given score has essentially the same meaning — i.e., same probability of recidivism — across groups. Second, Black offenders obtain higher average PCRA scores than White offenders (d= 0.34; 13.5% non-overlap in groups’ scores), so some applications could create disparate impact. Third, most (66%) of the racial difference in PCRA scores is attributable to criminal history — which is already embedded in sentencing guidelines. Finally, criminal history is not a proxy for race, but instead mediates the relationship between race and future arrest . Data are more helpful than rhetoric, if the goal is to improve practice at this opportune moment in history.