Evaluating the Predictive Accuracy of Sex Offender Risk Assessment Measures on UK Samples: A Cross-Validation of the Risk Matrix 2000 Scales

Leam A. Craig, Anthony R. Beech, Kevin D. Browne

[Sexual Offender Treatment, Volume 1 (2006), Issue 1]

Abstract

The predictive accuracy of the newly developed risk measures Risk Matrix 2000 Sexual/Violence (RMS, RMV) were cross validated and compared with four risk scales (RRASOR, SACJ-Min, SVR-20, and Static-99) in a sample of sexual (n = 85), violent (n = 46), and general (n = 22) offenders. The sexual offense reconviction rate for the sex offender group was 18% at 10 years follow-up, compared with 2% for the violent offenders. Survival analyses revealed the violent offenders were reconvicted at twice the rate of any other group. Reconviction data were analyzed using the area under the curve (AUC) of the Receiver Operating Characteristic (ROC). The RMV significantly predicted violent recidivism in the sex and combined sex/violent offender groups. The RMS obtained marginal accuracy in predicting sexual reconviction while the RMV obtained good accuracy at predicting violent non-sex reconviction. An item analysis revealed four factors not included in the risk scales significantly correlated with sexual and violent reconviction. Including these factors with Static-99, RMV and RMS increased the accuracy in predicting sexual reconviction but had a negative impact on the accuracy of RMV in predicting violent reconviction. The inclusion of static and dynamic risk factors with actuarial systems is discussed.

Key words: Sexual and violent offenders, actuarial and clinically-guided risk assessment, relative operating characteristic - area under the curve, predictive accuracy

Author address

Leam A. Craig, Forensic Psychology Practice Ltd
The Willows Clinic, 98 Sheffield Road, Boldmere
Sutton Coldfield
West Midlands, B73 5HW
Phone: 0121 377 6276
Fax: 0121 377 6027
e-mail: LeamACraig@aol.com