Road accident and safety statistics: guidance
Guide to reported road casualty statistics including notes and definitions, quality and methodology information and supporting technical documents.
Guidance on road casualty statistics
General guidance. Information about the road casualty statistics and how they are collected can be found in our background quality report. More detailed guidance on specific aspects of the statistics is available including on:
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adjustments to casualty severity as a result of the adoption of injury-based reporting by many police forces, provided below
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the use and interpretation of the contributory factors data, available in the contributory factors guide
Notes and definitions. A list of the main definitions used within these statistics are available from our notes and definitions page.
Data collection forms and guidance. Copies of the STATS19 forms and the guidance issued to police for completing them can be found on the forms and guidance page.
User engagement and STATS19 reviews. Details of the latest review of STATS19, together with details of how we engage with users of the statistics and a summary of recent user feedback are available from our user engagement page.
Severity adjustments
Since 2012, some police forces have moved to injury-based reporting systems which has impacted on the number of serious and slight injuries reported, affecting trends over time. The department has developed a method to adjust for this change.
Further details of the severity adjustments and when they are recommended to be used are available, including in our guide to severity adjustments.
Full technical details of the adjustment methodology can be found in the final technical report, (ODT, 4.9KB and the further annex (PDF, 3.1MB)
Quality and methodology
The majority of the road safety statistics are National Statistics, indicating that they are produced in line with the Code of Practice for Statistics. See National Statistics status of road casualty statistics for further information.
Quality of the statistics
An overall summary of the quality of the statistics assessed against the different dimensions of quality is available in our background quality report.
The department conducts more in-depth analysis to assess the quality of particular aspects of these statistics where relevant. Recent analyses include:
Data collection issues
Recent unexpected issues with data collection for two police forces - Avon and Somerset Police, and Staffordshire Police - mean the completeness and accuracy of the recorded road collisions in these two regions cannot be guaranteed as some collisions may be incomplete or missing.
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.
Staffordshire police have been under-reported collisions in 2022 due to issues with timely and completed processing. Rectifying actions have been discussed with the police force and are currently being implemented to resolve the situation.
This unlikely to noticeably impact on the overall Great Britain road collision trends, but caution should be applied when considering geographical breakdowns by these police force areas (RAS0401) and relevant local authorities (RAS0403) in these areas.
Methodology papers
Methodology notes providing further detail of the calculations involved in producing different elements of the published statistics are also available. These include:
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Valuation of road accidents and casualties (PDF, 25.3KB) including 1994 methodology paper (PDF, 609KB)
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Estimating total casualties from survey information (PDF, 19.5KB)
Older methodology papers are also available. The following papers relate to aspects of the statistics which are no longer routinely updated, but are retained for reference purposes
Updates to this page
Last updated 28 September 2023 + show all updates
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2022 reported road casualties Great Britain published.
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First published.