Comparing sex offender risk classification using the static-99 and LSI-R assessment instruments

This study compares sex offender risk classification using two popular actuarial risk assessment instruments - the Static-99 and the Level of Service Inventory-Revised (LS1-R). Despite their extensive use, the two scales assess different types of risk factors and research has yet to compare them. Method: Static-99 and LSI-R risk assessments were compared for 30 adult male sex offenders attending a community-based treatment program. Results: A paired Wilcoxon signed-rank test showed a significant difference (Z = -3.962, p < .001) between the instruments, with 63.3% of the sample classified as higher risk for reoffending by the Static-99 than by the LSI-R. Conclusions: The Static-99 may be a more conservative risk assessment tool. Yet because the LSI-R provides useful information about an offender's current needs not included on the Static-99, treatment providers should use both instruments. This more comprehensive assessment of criminogenic risk and need will better inform supervision and intervention decisions.