Question to the Ministry of Justice:

To ask the Secretary of State for Justice, pursuant to the Answer of 2 of March 2022 to Question 129199 on Prisoners: Location, how have the distances provided been calculated.

PQ129199 was answered using the following methodology.

Information on a prisoner’s residence is provided by prisoners on reception into prison and recorded on a central IT system. If no reception address was given, a prisoner's home, discharge or next of kin address was used. If none of these were available, committal court address was used as a proxy to determine the area in which a prisoner is resident.

Data for children (i.e. those aged under 18) was a snapshot average straight-line distance from origin address. It was based on the annual average running from April-March and is allocated against the end of the period (i.e. Apr10-Mar11 is plotted against 25/03/11). To avoid double-counting, 18-year-olds held in juvenile facilities were not included.

For Young Adults, aged 18-20, data was a snapshot average straight-line distance from origin address on the given dates. It included prisoners aged 18 years in juvenile facilities (Feltham A, Parc unit, Cookham, Werrington, Wetherby).

Adult (21+) data was a snapshot average straight-line distance from origin address.

Straight-line modelling is the most consistent calculation method. Attempts to model based on travelling distance are subject to high levels of temporal and geographical variation (e.g. inner city travel time) which would distort high-level data and make inter-group comparison less meaningful.