Sexual Abuse: A Journal of Research and Treatment, Vol. 18, No. 2, April 2006 (
Comparison of Two Risk Assessment Instruments
for Sexual Offenders
Published online: 6 April 2006
The current research examines the predictive validity of the Static-99 and the
SORAG in predicting sexual and violent recidivism among a sample of 258 treated
high-risk sexual offenders. While the SORAG was found to have moderate pre-
dictive accuracy for both sexual and violent recidivism over a 5-year follow-up
period, the Static-99 was found to only predict sexual recidivism. As well, the
actual recidivism rates in the current sample were compared to the published risk
percentages for each of the instruments. For both the Static-99 and the SORAG the
current sample re-offended at a lower rate than expected. Possible explanations
for this ﬁnding are discussed.
KEY WORDS: sexual offenders; risk assessment.
Over the course of the past 10 years a great deal of progress has been made
in developing instruments to assess the risk for sexual re-offence among convicted
sexual offenders. Two of the best-validated of these instruments are the Static-99
(Hanson & Thornton, 2000) and the Sex Offender Risk Appraisal Guide (SORAG;
Quinsey, Harris, Rice, & Cormier, 1998). These instruments are actuarial in nature,
relying wholly on historical factors in their scoring.
Hanson and Thornton (2000) developed the Static-99 using a large sample
of sexual offenders, combining items from the RRASOR and the SAC-J, an in-
strument used widely in the United Kingdom. They reported an Area Under the
Curve (AUC) value of .71 for predicting sexual recidivism. This was replicated by
Barbaree, Seto, Langton, and Peacock (2001) for both sexual (AUC = .70) and se-
rious (i.e., sexual and violent; AUC = .70) recidivism over a 4.5-year follow-up. In
an extension of the latter study, Langton (2003) similarly found that the Static-99
Regional Treatment Centre, Correctional Service of Canada, Kingston, Ontario, Canada.
To whom correspondence should be addressed at Regional Treatment Centre, Correctional Service
of Canada, Kingston, Ontario K7L 4V7, Canada.
2006 Springer Science+Business Media, Inc.