Letter in response to Admin-Based Population Estimates (ABPE) assessment

Ed Humpherson Director General Office for Statistics Regulation

Sent via email only

30 July 2025

Dear Ed,

Response to ABPE assessment

On 15 July 2024, the Office for Statistics Regulation (OSR) published initial findings on the new methods that the Office for National Statistics (ONS) is developing to produce population estimates for England and Wales, using administrative data sources.

We are now writing to update you on progress since your review. Our recent focus has been on ensuring the quality of our core population and migration outputs. A significant part of this work has been our activity to develop the sustainability and quality of our Admin-Based Population Estimates (ABPEs), and prepare our users for a transition to these new methods. It is vital that we support user confidence and understanding in these important statistics.

Since OSR’s review, we have published our ‘Action plan in response to the OSR assessment’ on 28 October 2024 and have provided updates every quarter in our ‘Quarterly Update on population and migration statistics’. On writing this letter today we have published our accredited official mid-2024 (and revised mid-2022 and mid-2023) population estimates (MYE) for England and Wales by age, sex and Local Authority. This is accompanied by ABPEs as official statistics in development to allow comparison with official statistics. The ABPE dataset will include for the first time estimates for upper tier local authorities and English regions, as well as England and Wales separately and combined. We will also publish estimates for population density, median age and components of change for migration separated into internal and international migration for the first time.

We have also published an article providing an overview of the quality of data sources used in mid-year 2024 admin-based population estimates, a Quality and methods guide and an update to the explainer article ‘Understanding mid-year admin-based population estimates for local authorities in England and Wales’.These products will enhance users’ understanding of the ABPEs.

Since we published the ‘action plan’ in October we have made progress on all eleven requirements to improve the trustworthiness, quality and value of ABPEs. In particular, we developed with users the criteria for moving to admin-based population estimates as official estimates of population, which was published in January 2025 and sets out clearly our acceptance standards. In May we assessed our progress against these criteria and made the decision for ABPEs not to become the official estimates in Summer 2025. We are now working towards making all the necessary improvements for Summer 2026. We will make a further assessment of the ABPEs against the acceptance criteria in Spring 2026.

To instill confidence in the ABPEs and ensure the methods are sound and subject to challenge we published our planned publication schedule, approach to revisions and the availability of data in our admin-based population and migration statistical system in February. Our update to the engagement strategy in May describes our work with LAs evaluate the quality of ABPEs. The sub-group of MARP has been created to provide independent challenge and quality assure methods and a cross-government group ensures communication and challenge from users within government.

We will continue to keep OSR updated on our progress and plans.

Yours sincerely,

Emma Rourke