The Recidivism of Sex Offenders in the Western Australian Prison Population

Five hundred and sixty sex offenders released from prisons over the period 1975–87 were followed for up to twelve years. A failure rate analysis (Wetbull ‘mixture’ model) provided estimates of probabilities of recidivism (re-incarceration) for any offence of 0.35 (for 95 per cent confidence interval it should lie between 0.25 and 0.46) for non-Aborigines and 0.80 (confidence interval 0.68–0.88) for Aborigines. Estimates or probabilities of committing further offences of violence, including further sex offences, were 0.21 (confidence interval 0.08–0.48) and 0.62 (confidence interval 0.13–0.95) respectively, but these figures are imprecise. A method of covariate analysis for recidivist data demonstrated that prior record, age, and race were crucial determining factors, but little evidence of specialization was found. It is argued that the evaluation of interventions should proceed on the basis of estimates of violent rather than repeat offending. The utility of incapacitation strategies and problems of crime prevention are discussed.