Flying Blind with Naked Factors: Problems and Pitfalls in Adjusted-Actuarial Sex-Offender Risk Assessment

Actuarial instruments are typically the centerpieces of evaluations pursuant to civilcommitment statutes for sex offenders. Almost as frequently as they rely on actuarial instruments, evaluators adjust actuarial data via weighing additional variables that are (presumably) correlated with recidivism. Typically, however, such variables are only weakly related to reoffending. This article reviews many problems and pitfalls undermining Adjusted Actuarial Assessment (AAA) and reports data demonstrating how illadvised this procedure is. Publicly available data do not support a claim in a recent meta-analysis (Hanson and Morton-Bourgon, 2009, p. 7), “For all three measures, for all types of raters, and for all outcomes, the adjusted scores showed lower predictive accuracy than did the unadjusted actuarial scores.” Based on available data, at its best, AAA neither increases nor decreases the accuracy of actuarial classification. At its worst, AAA dilutes actuarial accuracy