How we manage offenders

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How we measure re-offending

How do we know how successful we are and how do we measure rates of re-offending?

The current system for measuring re-offending compares the actual rate of proven re-offending with a predicted rate of proven re-offending.

If the actual rate is lower than the predicted rate, we have reduced re-offending.

Actual Rate: The actual rate is the number of offenders that are reconvicted in a particular year.

Predicted Rate: The predicted rate is the number of offenders that would be reconvicted, in year x, if the pattern of offending remained the same as in the baseline year, but allowed for observed changes in the make up of the offender population such as age, sex, criminal history etc.

Some groups of offenders are more likely to offend than others.

If, in a particular year, the offender group is made up of young men sentenced for theft, then that group would have a high risk of re-offending.

However, if the group largely comprised of women aged more than 50-years-old who have been sentenced for drink driving, then the risk of re-offending would be low. Therefore, in order to compare re-offending results fairly, we need to account for who is in the group.

As an offender’s propensity to re-offend is related to their age, sex, criminal history and many other factors, NOMS’ use of a predicted measure currently controls for changes in the make up of the offender population by calculating a predicted figure.

Measuring adult re-offending

Adult re-offending is measured by the reduction in the proportion of adult offenders discharged from prison or starting a community sentence who are reconvicted within two years, compared to the predicted rate.

Measuring youth re-offending

Youth re-offending is measured by the number of young offenders who re-offend within a one-year period following a pre-court disposal, court disposal, or release from prison and who are subsequently resanctioned, either through receiving another pre-court disposal or through a conviction.