Data and Methodology

This publication was produced by Scottish Government statisticians using administrative data from the Scottish Prison Service (SPS) management information system PR2. These data are collected by prison officers and staff for operational intelligence and logistical support.

It is important to note that the prison population is not static; individuals move in and out of the population every day. PR2 is a live system, updating constantly to capture changes to the state of the prison population. An extract of data from this system reports on the population at the moment in time the extract is drawn. Like many other operational databases, it was not designed to retain detailed historical data, or to provide retrospective information to assess how the prison population has changed over time.

Up until 2014, the Scottish Government held and reported on data compiled by combining and linking daily extracts from PR2. In addition, a number of the tables and figures in those previous reports were based on single-day ‘snapshots’ rather than the data compiled throughout the year.

Due to technological changes in 2014, it is no longer possible to produce these data. The dataset used in this publication (and all other publications produced from 2019-20 onwards) has been created using the information that is retained about the periods when prisoners occupied specific cells. Hence the population spine underlying this publication is termed “cellWise”, or the cellWise data. More detail on how these data are constructed is provided in the accompanying Technical Manual[i].

The construction of the cellWise data is fundamentally different, both to the previous data design and to the aggregation produced by SPS in the interim. It has therefore not been possible to align these results exactly with publications pre 2019-20. Source Comparison shows that trends and approximate levels are sufficiently aligned for meaningful interpretation of high level prison population trends. Where uncertainties do arise, these will be highlighted throughout this report, and are also listed in the Source Comparison. The measurements throughout this publication therefore represent estimates based on the data as constructed.

The Scottish Government is seeking views on its statistical products. To take part in this consultation, please complete the Scottish Government official statistics feedback survey.

Technical Manual

Information about the derivation of the cellWise analytical dataset and the various measurements and factors used in this report is provided in a stand-alone technical manual, available from the Scottish Government website[ii].

Supplementary Tables

The following supplementary tables are available alongside this publication in Excel format[iii]

Table 1: Supplementary Tables

Interactive Analytical Tool

An interactive tool has been produced alongside this report to allow users access to a bespoke analysis.

https://scotland.shinyapps.io/sg-prison-population-statistics/

A worked example using this tool to explore statistics on time on remand was published in the September 2022 edition of the JAS Monthly Data Report[iv].