See criticism of this study by R. Hanson.
Recidivism risk is an important component of criminal justice and correctional planning, especially when it comes to sex offenders who may pose physical danger to others. The current study assessed the recidivism rate of 320 sex offenders and 31 violent non-sex offenders over a 25 year follow-up period.
Participants were sex offenders referred for psychiatric treatment by the court, police, probation services, defense lawyers, or mental health professionals between 1966 and 1974. The comparison group was comprised of the 31 violent non-sex offenders. Recidivism data were drawn in 1994 and 1999 from the RCMP database and from hospital records.
Results of statistical analyses indicated that approximately 3 out of 5 sex offenders were re-convicted of a sexual offense during the 25 year follow-up. When all offenses were considered, including non-sex offenses, four out of five sex offenders recidivated during the follow-up period.
Child sexual abusers and exhibitionists were most likely to re-offend, while incest offenders were the least likely to re-offend. The findings reveal that sex offense recidivism remains a problem over a significant part of a sex offender’s adult life.
Correctional planning for sex offenders should include actuarial measures of risk, although they should be used with caution until more long-term studies of recidivism risk among this population can be carried out. Tables, notes, references ..Source.. by Ron Langevin ; Suzanne Curnoe ; Paul Fedoroff ; Renee Bennett ; Mara Langevin ; Cheryl Peever ; Rick Pettica ; Shameen Sandhu ---- Full copy here
Right now they are mostly about Treatment Costs.