Weights matter: Improving the predictive validity of risk assessments for criminal offenders

Abstract

This article explored whether the use of optimal weights can improve the predictive validity of risk assessments for criminal offenders, an issue the literature has long been divided on. By analyzing the unweighted instrument Level of Service Inventory – Revised (LSI-R), the study provided evidence in favor of optimal weights, showing that a weighted instrument clearly outperforms an unweighted one in predicting recidivism. The magnitude of the difference in performance would not be expected by some of the literature. The study also showed that objective and easily measurable items of such instruments were associated with larger weights than subjective items.