Prediction of re-offence using the SIR-R1 and a proxy

Predicting whether an offender will re-offend is complex and, obviously, very important in making release-related decisions. CSC uses the Statistical Information on Recidivism – Revised 1 (SIR-R1) as part of this assessment. The scale, used only with non-Aboriginal male offenders, estimates the likelihood of an indictable offence being committed within three years of release.

This study aimed to determine whether the SIR-R1 continues, despite changes to the offender population, to effectively predict re-offence. Also of interest was whether the SIR-R1 could predict violent and sexual re-offence. Finally, the study also examined the potential applicability of a proxy of the scale to male Aboriginal offenders and to women offenders (both Aboriginal and non-Aboriginal).

We examined the SIR-R1 scores and post-release outcome of the 11,571 male non-Aboriginal offenders released from 2005 to 2007. In addition, we used a proxy of the SIR-R1 to approximate scale scores for all Aboriginal male (N = 2,846), Aboriginal women (N = 251), and non-Aboriginal women offenders (N =684) released in the same period.

Results clearly showed that the SIR-R1 continues to appropriately predict general re-offence within three years among non-Aboriginal male offenders. In fact, results were quite similar to those of nearly a decade ago, demonstrating that despite changes in the offender population, the scale’s predictive accuracy has not decreased.

In addition, despite the fact that the SIR-R1 was constructed only to predict general re-offence, its ability to predict violent re-offence was satisfactory. The SIR-R1 was not predictive of sexual re-offence.

Finally, the application of the SIR-R1 proxy to male Aboriginal offenders and to women offenders produced positive results. The proxy predicted re-offence in non-Aboriginal women offenders better than in their male counterparts. Predictive accuracy was somewhat less for Aboriginal offenders, though it reached levels considered acceptable.

Results clearly supported the continued use of the SIR-R1 in case planning and release decision-making for non-Aboriginal male offenders.

Further research is proposed to identify SIR-R1 items, together with culturally-informed and gender-informed variables, that can be combined to create measures of risk of general re-offence for Aboriginal and women offenders. The creation of such measures will strengthen CSC and the Parole Board of Canada’s ability to predict risk of re-offence for all offenders, regardless of gender and ethnicity.

Barnum, G. & Gobeil, R. (2012). Prediction of re-offence using the SIR-R1 and a proxy. Research Report R-281.Ottawa, ON: Correctional Service of Canada.

To obtain a PDF version of the full report, contact the following address: research@csc-scc.gc.ca

Prepared by: Geoffrey Barnum & Renée Gobeil