Road casualty statistics: known data issues
Updated 28 September 2023
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This publication is available at https://www.gov.uk/government/publications/reported-road-casualty-statistics-background-quality-report/road-casualty-statistics-known-data-issues
The background quality report for the reported road casualty statistics provides an overview of the statistics, how they are compiled and validated, and an assessment against the different dimensions of statistical quality.
While the road casualty statistics are considered to meet the high standards required to be badged as ‘National Statistics’, there are several known issues impacting on their quality.
This page provides details of specific known issues affecting the STATS19 dataset which is used to compile the department’s road casualty statistics. Further details are available on request from the road safety statistics team.
2022 known issues
Incompleteness of data for Staffordshire police
Staffordshire police have under-reported collisions in 2022, and for several earlier years, due to issues with timely and completed processing where reportable collisions within their systems were not included in STATS19 returns. Rectifying actions have been discussed with the police force and are currently being implemented to resolve the situation.
However, the data for STATS19 is likely to under-count the number of collisions and casualties for Staffordshire relative to other police forces, to a growing degree over time. It is unlikely that this historical issue will be rectified and no attempt has been made to impute for missing data.
In particular, reductions in casualties in Staffordshire from around 2016 are likely to be impacted by completeness of the data reported, as well as any genuine change in road safety in the area. Therefore comparisons between Staffordshire police force or local authority areas and other areas should be interpreted with caution.
Avon and Somerset police data
Avon and Somerset police changed collision recording systems during 2022. The transition has exposed some formatting and export issues. Most notably key data was missing, which has impacted Local processing authorities (LPA) ability to process and validate the data. This has caused delays in supplying data to the department and as a result some data may be missing or incomplete at time of publication.
Greater Manchester police data
Greater Manchester Police transitioned to a new reporting system in 2021. Minor total differences were reported by Transport for Greater Manchester for 2021 data. Some collisions were not supplied in time for inclusion and some additional deletions have been reported. The overall totals are not significantly different to those published as part of the department’s statistics and STATS19 datasets.