Static-2002 coding rules (2009) - Static-99

Thornton in the low risk category. Compared to other adult male sexual offenders in
Canada, his score falls into the lowest percentile (zero). Factoring in the 95% confidence
interval, this range could be as wide as the zero to 6.1 percentile. This percentile range
means that zero to 6.1 percent of sex offenders in Canada scored at or below Mr.
Thornton’s score. Conversely, 93.9 to 100 percent of sex offenders in Canada scored
higher.
The recidivism rate of sex offenders with the same score as Mr. Thornton would be
expected to be two-fifths of the recidivism rate of the typical sexual offender (defined as a
median score of 4).
There have been several studies examining the sexual recidivism rates associated with Static-
2002 scores. Hanson, Helmus, and Thornton (in press) summarized the results of 8 samples of
sexual offenders (N = 3,034) drawn from Canada, the United States, the United Kingdom, and
Denmark. In these samples, recidivism was defined as charges in half of the samples and as
convictions in the other half. 1
These recent studies found that there is meaningful variation in the sexual recidivism rates based
on factors not measured by Static-2002. Samples that were preselected to be high risk (3 samples)
show the highest recidivism rates, and routine samples from the Correctional Service of Canada
(CSC; 3 samples) show recidivism rates substantially lower than the original developmental
samples. Consequently, in order to evaluate the recidivism risk of Mr. XXX, we need to consider
the extent to which he resembles the typical member of the preselected high risk samples or the
typical member of the CSC samples.
The logistic regression estimates of sexual recidivism are “bounded” by the lower rates of
recidivism found in the CSC samples and the higher rates found in the preselected high risk
samples.
EXAMPLE – Mr. Hanson with a score of 9
For sexual recidivism, the range of risk for a score of 9 on Static-2002 is 19.7% to 32.9% in
five years and 23.6% to 40.8% in ten years.
EXAMPLE – Mr. Thornton with a score of 0
For sexual recidivism the range of risk for a score of 9 on Static-2002 is 1.3% to 6.7% in five
years and 1.3% to 11.3% in ten years.
These recidivism rates, derived from the routine CSC and preselected high risk samples, are
empirically based actuarial estimates. Given that the differences between samples are not fully
known, evaluators need to use their professional judgement in order to make statements about
where in this range the risk of a particular offender is situated.
This judgement should be based on a careful consideration of the features that Mr. XXXX shares
with the routine CSC samples and the preselected high risk samples. Determining an offender’s
1 Convictions provide a conservative estimate of sexual offending as research has shown that most sexual crimes do not result in
charges or convictions, and when protected from prosecution, sexual offenders report they have committed more sexual crimes than
they have been caught for. Another important consideration is that risk for reoffence increases as the opportunity time to reoffend
increases. Thus, although the new Static-2002 norms provide rates for a maximum of a 10-year period, cumulative risk continues to
increase after 10 years.
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