The probation data included in this dataset is sourced from National Delius (nDelius). nDelius is used for the management of offenders on Probation, or in the community. A service user (offender) is referred to nDelius by a court and an event is created in nDelius. Broadly, events are either a sentence or pre-sentence. An event can only ever have one sentence outcome (disposal). One court case can receive multiple sentences/disposals so more than one event may run at the same time.

A service user will receive one offender_id per court case however duplicates can happen by mistake. The variable estimated_offender_id uses a process of data deduplication to eliminate these duplicates and group them under the same service user cluster.

The accuracy of the source data is dependent on the quality assurance processes and local recording practices intrinsic to the source data systems used by HMPPS staff (nDelius).