January, 2003
EXECUTIVE SUMMARY
In late 1999, the Sex Offender Assessment Board (SOAB), for its work assessing sexual offenders, both for court ordered and PBPP cases, began use of the RRASOR, Static 99, and MNSOST-R. The PBPP, upon recommendation of the SOAB, adopted the Static 99 as its objective risk assessment instrument to assist in determining the static level of risk to re-offend sexually posed by sex offenders. The Static-99 was first developed by Canadian researchers and includes ten items that take into account the offender’s prior criminal history, incidence of violence, relationship to the victim, and personal characteristics that may influence the decision of the PBPP. These variables have been shown to be statistically associated with recidivism in other jurisdictions. Within the Static- 99, there are four items that compose a condensed risk assessment instrument known as the Rapid Risk Assessment for Sexual Offense Recidivism (RRASOR).
Summary of Research Design and Methodology
In order to measure the reliability of Static-99/RRASOR, two reliability tests were completed. The first consisted of a pilot test of 41 cases that were coded by independent scorers using case file data. A second test was conducted on a larger sample of 220 cases that were drawn for the validation study.
The validation sample consisted of 550 cases that reflected prisoners convicted of sex crimes and were released either between 1994 and 1995 (N=356) or in 2000 (N=194). The characteristics of the 550 cases were compared to the total universe of all released sex offenders. This analysis found the sample to be representative of all sex releases for the two time periods.
Reliability Findings
Two reliability tests were conducted to ascertain the reliability of three sex offender risk assessment instruments. In addition to the Static-99/RRASOR, the reliability of the Minnesota Sex Offender Screening Tool-Revised (MnSOST-R) was also assessed. The first test was a limited pilot study that consisted 41 cases, each scored twice on the three instruments. In order for the scoring of the items to be judged reliable, the two raters needed to assign the same score for at least 80 - 90 percent of the cases.
The pilot study revealed that the level of inter-rater reliability was unacceptably low for the MnSOST-R, based in large part on the information collected in the records of both the DOC and PBPP. While, the Static 99/RRASOR had higher levels of reliability, significant staff training and item refinement/clarification was required to improve the scoring of the Static 99/RRASOR; DOC and PBPP records are not a factor for RRASOR/Static 99. ..more.. by James Austin, Ph.D., Johnette Peyton, M.S., Kelly Dedel Johnson, Ph.D.
September 14, 2007
RELIABILITY AND VALIDITY STUDY OF THE STATIC-99/RRASOR SEX OFFENDER RISK ASSESSMENT INSTRUMENTS
August 17, 2007
Sex Offender Risk Assessment
June 30, 2006
Prepared for: Missouri Sentencing Advisory Commission
Executive Summary
Compared to clinical methods, actuarial risk instruments are a preferred method to discern sex offenders risk for sexual as well as violent recidivism because, unlike clinical practices, they are considered inexpensive, objective and modestly accurate. Scientists argue that risk instruments that employ only static, or historic measures of offender characteristics, rather than dynamic, are certainly sufficient for the purposes of gauging individuals’ likelihood of recidivism. In fact, Harris and Rice (2003:207) contend that dynamic constructs are “unnecessary for anticipating who will recidivate in a given time period”; furthermore they state that “very accurate statements about the likelihood of another…offense can be based upon knowledge of an individual’s lifetime conduct.” In their view, offender risk scales that incorporate only static information are essentially capturing factors that refl ect a person’s underlying antisocial propensity.
Although there are a considerable number of risk instruments available for corrections officials to utilize, far fewer have been rigorously evaluated. Of those that have, Harris and Rice (2003) recommend that the MnSOST-R and the Static-99 are two of the most “promising” scales for predicting sexual recidivism. An emerging body of work also suggests that the SORAG is quite effectual in terms of its predictive accuracy. Additional empirical research is likely to surface which will provide further evidence of the statistical accuracy of sex offender risk instruments.
For the remainder of this paper: by Dr. Beth Huebner (Prepared by: Institute of Public Policy, Truman School of Public Affairs, University of Missouri – Columbia)
