Predictive Validity of the Static-99 and Static-99R in Switzerland

Abstract

This study evaluated the validity of the Static-99 and Static-99R in assessing sexual recidivism in Switzerland, based on a sample of 142 male sex offenders. Both tools showed predictive validity, but the Static-99R had better discrimination (OR = 1.82, AUC = .81) and calibration (Brier = .078, P/E = 0.96) than the Static-99. A cut score of four on the Static-99R maximized sensitivity (92.9%) and specificity (60.2%). However, although most offenders (98.7%) with a score < 4 did not commit sexual offenses in the 5-year follow-up period, only one in five (20.3%) offenders with a score ≥ 4 actually recidivated. Furthermore, the predicted number of recidivists in the well above average risk category (Static-99R ≥ 6) was 24% higher than expected in routine samples. The results suggest that the Static-99R may be a useful screening tool to identify low-risk individuals but offenders with scores ≥ 4 should be subjected to a more thorough assessment.

Investigating the predictive validity of Static-99/99R scores in a sample of older sexual offenders

“…The three Australian published research articles using samples with wide age ranges obtained similar AUC values to those identified during the current research (Allan et al, 2006;Reeves et al, 2018;Smallbone and Rallings, 2013), suggesting that both the Static-99 and Static-99R perform similarly in older samples as in younger samples. The AUC values obtained in this study were also consistent with international studies using samples of varied age, showing a moderate ability to discriminate between recidivists and non-recidivists using the Static-99 and Static-99R (see Boccaccini et al, 2017;de Vogel et al, 2004;Goncalves et al, 2020;.…”

Testing the Static-99R as a Global Screen for Risk of Sex Crime Recidivism in a Norwegian Routine Sample

“…Several studies have supported Static-99R’s predictive abilities in European countries ( Craig et al, 2004 ; De Vogel et al., 2004 ; Eher et al, 2013 ; Gonçalves et al, 2020 ; Sjöstedt & Långström, 2001 ). Hanson et al (2011) reviewed 63 Static-99 predicting studies involving 70 distinct samples and found that the predictive accuracy of Static-99 was significant in Canada, the United States, the United Kingdom, New Zealand, Australia, Belgium, Germany, Denmark, Holland, Switzerland, Sweden, Austria, and Japan.…”

Combining Static and Dynamic Recidivism Risk Information Into the Five-Level Risk and Needs System: A New Zealand Example

“…, replacing O with P for the E/P index. Following Gonçalves et al (2020), we concluded no statistically significant difference (p > .05) between the expected and observed (or predicted) number of recidivists if each 95% CI included 1.…”

“…The E/O index is the ratio of expected (E) to observed (O) number of recidivists and is an effect size for the calibration of recidivism risk tools (Hanson, 2017), with a score of 1 representing perfect calibration. The E/P index replaces observed number of recidivists with predicted number of recidivists using model-derived absolute recidivism rate estimates (Gonçalves et al, 2020). We calculated the expected (E) number of recidivists (average recidivism rate proposed by the 5-Level System multiplied by number of people in each level) and predicted (P) number of recidivists (absolute recidivism rate estimates multiplied by number of people in each level) and used the following formula to calculate confidence intervals (CIs): 95…”