SPS Management Information Technical Manual

In this section we outline the major features of the SPS Daily MI collection (“spsMI”) and contrast it with the information collected for the production of the Accredited Official Statistics.

Demographics and characteristics

A partial collection of prisoner characteristics is extracted daily, intersecting with the factors extracted for cellWise[i]. The live age field is used in place of a date of birth calculation. Where these characteristics are subject to change or amendment, those variations may be detected by snapshot comparison.

Legal Information

spsMI provides the live legal status for each individual at the time of the snapshot. This adds information not available in the cellWise data, which cannot detect transitions from sentenced statuses to remand, or (within remand) from convicted awaiting sentence status to untried.

For each individual a list of all currently active legal warrants is also extracted. This means we can determine the index offence from a smaller subset of warrants than might be present over a longer occupancy period. This is in contrast to the cellWise data[ii], which identifies the most serious offence from the full list of warrants intersecting with an occupancy period.

The live field overall sentence length is the result of complex calculations made by prisoner officers in establishments based on the currently active warrants and notes from court clerks. It is updated whenever that information changes. This calculation cannot be replicated for the cellWise data set due to the ambiguity around warrants active at any point in time, the amount of time left to serve on the suite of warrants currently in force and whether sentences are to be served consecutively or concurrently. Unlike index sentence length, as used in the accredited official statistics[iii], it therefore allows the direct separation of the population into short- and long-term prisoners and can be used to chart the change in sentence length over the course of an occupancy period.

Keys and Identifiers

The Prisoner Number identifier used in the cellWise data are also present in the spsMI. Added to this is the S-number identifier used by Police and Courts.

Linkage between prisoner identifiers and court cases has been performed with a high level of coherence in identifiers for recent cases (see for example Short custodial disposals from court and the prison population).