Formerly prisons were ranked on their performance in the prisons weighted scorecard. However, this formed only one element of the final ratings for prisons. A new prison rating system was introduced for 2009-10, but the version used to produce the ratings for Quarter 1 did not lend itself to the production of a performance table. The system has been refined and will produce for internal use by NOMS prison rankings as part of the package when Quarter 2 ratings are published.
The new system produces initial quarterly assessments based on available data. Additional factors such as escapes and recent inspection results are then taken into account in the final ratings by an independent external moderation panel which includes a non-executive representative and is chaired by the Director of Criminal Justice Group in the Department. For this reason the final quarterly ratings published by the Department may differ from the data-driven rankings produced by NOMS.