Document Title: A Model of Static and Dynamic Sex Offender Risk Assessment

The purpose of the present study was to test models of combining static and dynamic risk measures that might predict sexual recidivism among adult male sex offenders better than any one type of measure alone. Study participants were 759 adult male sex offenders under correctional supervision in Vermont who were enrolled in community sex offender treatment between 2001 and 2007. These offenders were assessed once using static measures (Static-99R, Static-2002R and VASOR) based on participants’ history at the date of placement in the community. A 22-item dynamic risk measure (SOTNPS) was used multiple times to assess participants, shortly after their entry into community treatment and approximately every six months thereafter. Analyses of SOTNPS scores resulted in the development of a new 16-item dynamic risk measure, the Sex Offender Treatment Intervention and Progress Scale (SOTIPS). At fixed oneand three-year follow-up periods from participants’ initial, second, and third dynamic risk assessments, the SOTIPS and Static-99R, the static risk measure selected for further analysis in the present study, each independently showed moderate ability to rank order risk for sexual, violent, and any criminal recidivism and return to prison. A logistic regression model that combined SOTIPS and Static-99R consistently predicted recidivism and outperformed either instrument alone when both instruments had similar predictive power. Participants who demonstrated treatment progress, as reflected by reductions in SOTIPS scores, showed lower rates of recidivism than those who did not.