Assessment of dynamic risk factors: an independent validation study of the Violence Risk Scale: Sexual Offender Version.

The Violence Risk Scale: Sexual Offender Version (VRS:SO) is a rating scale designed to assess risk among sexual offenders and the degree of change achieved in treatment. The scale consists of 7 static and 17 dynamic risk items, with protocols for measuring treatment change based on the Transtheoretical Change Model. The aim of the current study was to evaluate the psychometric properties of the VRS:SO on an independent sample of 218 child molesters who received treatment at a prison-based program in New Zealand and who were followed up for an average of 12.2 years. Supporting the initial validation of the VRS:SO, the results indicated good interrater reliability, concurrent validity, and predictive validity of the measure--VRS:SO scores were predictive of sexual recidivism (for Dynamic and Total scores, area under the curve value approximately .80), and the dynamic scale made significant incremental contributions after controlling for static risk. The authors also analyzed the validity of the factor structure of the VRS:SO dynamic scale and compared the measure with an alternative measure of dynamic risk based on a self-report psychometric battery.