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Development of Vermont Assessment of Sex Offender Risk-2 (VASOR-2) Reoffense Risk Scale

NCJ Number
Date Published
June 2014
20 pages
Robert J. McGrath, Michael P. Lasher, Georgia F. Cumming, Calvin M. Langton, Stephen E. Hoke
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.
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). (Publisher abstract)
Date Created: June 28, 2015