Evaluating and Improving Risk Assessment Schemes for Sexual Recidivism: A Long-Term Follow-Up of Convicted Sexual Offenders

March 2007 217618

EXECUTIVE SUMMARY
Risk assessment plays a central role in the management of sexual offenders in the criminal justice system, impacting every level of decision-making. The specification of which offenders should be included in state registration or community notification, the distribution of treatment opportunities in prison, the determination of parole eligibility, the allocation of resources in monitoring and supervising offenders in the community, and the ultimate decision to remove the most serious offenders from the community through civil commitment all involve critical choices involving risk. The serious consequences to potential victims, to those offenders who no longer pose a threat to the community, but are denied their civil liberties, and to critical community funds that may be squandered as the result of inaccurate decisions all demand the guidance of the most accurate actuarial algorithms available. Because decisions must be made—even doing nothing constitutes a decision—to choose not to employ the most accurate decision-making algorithms is to choose to pay the costly price of a suboptimal decision.

The aim of the present study was to evaluate and to improve the decision-making algorithms that have been generated to assess risk in sexual offenders. More specifically, it was the task of this research project to evaluate the extant actuarials in a sample of sexual offenders on whom long-term follow up were available. We assessed the comparative accuracy of the major risk instruments over time and over subsamples, explored their underlying factor structure, examined the accuracy of a new assessment protocol (SRA Need Assessment; Thornton, 2002), and explored the potential for generating improved predictive instruments.

In a prior study we (Knight, 1999; Prentky, Knight, & Lee, 1997) had followed 599 offenders who had been referred to the Massachusetts Treatment Center (MTC) for evaluation between 1959 and 1984. Of these 266 (Bridgewater Treatment [BT] sample) had been committed to MTC as “sexually dangerous” and subsequently released, and 333 (Bridgewater Observation [BO] sample) had been determined not to be sexually dangerous and returned to finish their sentences. Of the 333 BO offenders 200 constituted a matched sample (on age at evaluation, marital status, and number of prior crimes) and 200 were randomly sampled from the entire sample BO population evaluated. There was an overlap of 67 offenders selected by both the random and matched process. For all these offenders we had accessed and integrated four outcome record sources, including the Massachusetts Board of Probation records, the Massachusetts Parole Board records, the Massachusetts Treatment Center Authorized Absence Program records, and the Federal Bureau of Investigation (FBI) records.

In the present study we accessed the archival clinical files for these offenders and coded these records both on modern empirically-derived, mechanical actuarials that have been developed since 1997 for predicting sexual recidivism, including the RRASOR (Hanson, 1997), the Static-99 (Hanson & Thornton, 2000), the Static-2002 (Hanson & Thornton, 2003), the SORAG (Quinsey, Harris, Rice, & Cormier, 1998), the MnSOST-R (Epperson, Kaul, Huot, Hesselton, Alexander, & Goldman, 1998), and the Risk Matrix 2000 (Thornton et al., 2003), on two structured clinical guidelines, the SVR-20 (Boer, Hart, Kropp, & Webster, 1997) and the A-SOAP-II (Prentky & Righthand, 2003), and on a new experimental measure, the SRA Needs Assessment (Thornton, 2002). Offenders were also categorized in the Massachusetts Treatment Center Rapist (MTC:R3) and Child Molester (MTC:CM3) typologies and diagnosed according the DSM-IV Antisocial Personality Disorder and Conduct Disorder criteria. All codings and judgments were carried out without any access to or knowledge about the follow-up status of the offenders.

The final report addressed six basic questions. We summarize the findings for each using this framework: ..more.. by Raymond A. Knight, Ph.D. ; David Thornton, Ph.D.