Guidance

Guide to methodology for drink-drive statistics

A guide to the methodology used in producing estimates in the Department for Transport's drink-drive casualty statistics.

• From: Department for Transport
• Published: 31 July 2025

Applies to England, Scotland and Wales

Documents

Methodology note for reported road casualties in Great Britain involving illegal alcohol levels

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Details

In 2025, there was a change to the methodology which caused slight changes to estimates. More details can be found in the methodology note.

This guide describes the methodology used in the production of the statistic included in the publication “Reported road casualties in Great Britain involving illegal alcohol levels”.

The guide covers:

• drink-drive legal limits and definitions
• data sources
• completeness of data and reliability of drink drive estimates
• adjustments to account for missing data
• uncertainty in the statistics and how it’s communicated
• timeliness of the statistics

Further information on the drink-drive methodology can be addressed to the road safety statistics team via the contact details below.

Road safety statistics

Email roadacc.stats@dft.gov.uk

Published 31 July 2025