title: Interpreting multiple risk scales for sex offenders: evidence for averaging.
abstract: This study tested 3 decision rules for combining actuarial risk instruments for sex offenders into an overall evaluation of risk. Based on a 9-year follow-up of 940 adult male sex offenders, we found that Rapid Risk Assessment for Sex Offender Recidivism (RRASOR), Static-99R, and Static-2002R predicted sexual, violent, and general recidivism and provided incremental information for the prediction of all 3 outcomes. Consistent with previous findings, the incremental effect of RRASOR was positive for sexual recidivism but negative for violent and general recidivism. Averaging risk ratios was a promising approach to combining these risk scales, showing good calibration between predicted (E) and observed (O) recidivism rates (E/O index = 0.93, 95% CI [0.79, 1.09]) and good discrimination (area under the curve = 0.73, 95% CI [0.69, 0.77]) for sexual recidivism. As expected, choosing the lowest (least risky) risk tool resulted in underestimated sexual recidivism rates (E/O = 0.67, 95% CI [0.57, 0.79]) and choosing the highest (riskiest) resulted in overestimated risk (E/O = 1.37, 95% CI [1.17, 1.60]). For the prediction of violent and general recidivism, the combination rules provided similar or lower discrimination compared with relying solely on the Static-99R or Static-2002R. The current results support an averaging approach and underscore the importance of understanding the constructs assessed by violence risk measures.
authors.affiliation: Institute of Forensic Psychiatry.
authors.forename: Robert J B
authors.initials: RJ
authors.lastname: Lehmann
authors.forename: R Karl
authors.initials: RK
authors.lastname: Hanson
authors.forename: Kelly M
authors.initials: KM
authors.lastname: Babchishin
authors.forename: Franziska
authors.initials: F
authors.lastname: Gallasch-Nemitz
authors.forename: Jürgen
authors.initials: J
authors.lastname: Biedermann
authors.forename: Klaus-Peter
authors.initials: KP
authors.lastname: Dahle
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002650:Child Abuse, Sexual / Q000517:prevention & control / Q000523:psychology; D003627:Data Interpretation, Statistical; D006801:Humans; D008297:Male; D008875:Middle Aged; D011581:Psychological Tests; D011902:Rape / Q000517:prevention & control / Q000523:psychology; D018570:Risk Assessment / Q000379:methods; D055502:Secondary Prevention; D012742:Sex Offenses / Q000523:psychology*; D055815:Young Adult