The Impact of Base Rate Utilization and Clinical Experience on the Accuracy of Judgments Made with the HCR-20

Abstract

It was hypothesized that clinical judges would make ineffective use of base rate information and that their level of experience in the forensic psychology field or with risk assessment would have no bearing on their ability to make accurate clinical judgments. A convenience sample of 43 members of two professional psychological organizations was used to determine the effects of base rates and experience on predictions made from a “blind” analysis of the Historical, Clinical, Risk-20 (HCR-20). Consistent with the hypotheses, base rate neglect was prevalent in the current study and prior experience had no effect on predictive accuracy.