Failure of Static-99 and SORAG to predict relevant reoffense categories in relevant sexual offender subtypes: A prospective study

An Austrian sample of 275 sexual offenders was assessed clinically as well as with actuarial tools including the Static-99 and the Sexual Offender Risk Appraisal Guide (SORAG) before being released from prison. After an average time of 3.6 years at risk, their relapse rates were correlated with their previous scores on these two instruments. The results demonstrate that the Static-99 and the SORAG, although predicting certain types of relapses quite well, are much better in predicting the non-relapse than the relapse: Less than 50% of the high scorers on both instruments relapsed during the follow-up time of 3.6 years at risk and were again convicted for a new sexual or violent offence. For practical purposes, e. g. for the clinician and the judge being in charge of deciding about the release of an individual offender, these overall results as well as more specific results for certain types of relapses with low base rates are discussed.