The
Offender Assessment System:an evaluation of the second pilot
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The Offender Assessment System (OASys) is a structured clinical assessment
tool used by adult correctional services in England and Wales. It was developed
to assess offending related needs, likelihood of reconviction and risk of serious
harm. Offenders are assessed at pre-sentence stage, at the start of most community
and custodial sentences and at regular intervals during the sentences. These
assessments aid effective management of offenders and targeting of interventions
designed to reduce reconviction. This Findings reports on offenders’ risk/need
profiles, predicting reconviction with OASys and actions taken since the pilots.
The key findings are that OASys reveals considerable variation in risk/need
profiles between different groups of offenders, and OASys scores are a good
predictor of reconviction, with 2 year reconviction rates of 26% for ‘Low’,
58% for ‘Medium’ and 87% for ‘High’ likelihood offenders.