Development of Vermont assessment of sex offender risk-2 (VASOR-2) reoffense risk scale.

The present study aimed to revise the Vermont Assessment of Sex Offender Risk (VASOR) Reoffense Risk Scale, a commonly used sex offender risk assessment tool. The revised tool was named the VASOR-2. Among models tested to revise the scale, a logistic regression model showed the best balance between simplicity of use, goodness of fit, and internal validity (as tested with K-10 cross-validation), and maximized predictive accuracy. Predictive accuracy was tested using four meta-analytically combined data sets drawn from Canada and Vermont (N = 1,581). At 5-year fixed follow-up, the predictive accuracy for sexual recidivism for VASOR-2 (AUC = .74) was similar to the VASOR (AUC = .71). The findings show the VASOR-2 is well calibrated with observed recidivism rates for all but the highest risk sex offenders. The instrument showed good interrater reliability (ICC = .88). An advantage of the VASOR-2 is that it has fewer items and simpler scoring instructions than the VASOR. Norms are presented for a contemporary, nonselected, routine sample of Vermont sex offenders (n = 887).