2. Background

This report shares the findings of OSR’s review of the adequacy of UK-wide comparable statistics and data. This review has been undertaken within a wider landscape of recent reviews and forums where findings and recommendations on coherence and UK comparability have been shared publicly. These wider reviews highlight both the challenges with, and the user needs for, comparable data across the UK.

A recurring issue highlighted in the recent published reviews is the persistent challenges for the statistical system in delivering comparable UK-wide statistics and data on priority topics.

Aims and context

Our vision is that official statistics should serve the public good. Official statistics serve the public good when they provide insight that allows them to be used widely for informing understanding and shaping action.

Recent reviews highlight that the lack of comparable UK-wide statistics is hindering meaningful comparisons of performance and outcomes across the UK, making it challenging for anybody wishing to understand the different experiences of citizens across the four UK nations. While there is definite value in statistics and data that meet local users’ needs, to be truly useful for informing understanding and shaping action, statistics should also, wherever possible, be comparable at different levels (internationally, nationally, regionally and locally) and over time, and available through consistent time series.

Though statistical producers have done good work in this area, the comparability of statistics across the UK has long been a challenge in the UK statistical system. In many ways this challenge is a consequence of the UK political and statistical system, where responsibility for policy, data collection, analysis and evaluation is devolved to different levels. As a result, data and statistics are often designed to meet local needs. But comparisons across different geographies are important for understanding differences in outcomes across the UK and informing democratic debate. Without specific efforts and appropriate governance and resources, a decentralised statistical system will not naturally deliver this set of user needs.

This review comes shortly after the publication of recommendations on the 2031 Census by the Office for National Statistics, the National Records of Scotland and the Northern Ireland Statistical and Research Agency (NISRA). While these recommendations call for a census to take place in all parts of the UK, they also put a focus on the opportunities presented by supplementing the census with wider data sources. In our view, this focus, alongside the recommendations of this report, provide a real opportunity for change and to grasp the issues that have been a long-running collective challenge for statistical producers.

There are three important reports which provide the context and motivation for this report:

• In March 2024, The Independent Review of the UK Statistics Authority by Professor Denise Lievesley highlighted the importance of comparability to allow users to make valid comparisons over time, space or non-geographical areas. It set out the role of comparable data in ensuring that changes in data reflect realities and are not instead artefacts of different methodologies. The review highlights the challenges of the complexity of the statistical system and the significant resource disparities, and called for solutions to be found. It concluded that there is a need for a strengthened Concordat on Statistics and to ensure funding is available to support the harmonisation of key data.
• In May 2024, the Public Administration and Constitutional Affairs Committee (PACAC)’s Transforming the UK’s Evidence Base report set out the challenges and opportunities in obtaining comparable data across the four nations of the UK. The report highlights the difficulties in comparing the experiences of citizens across between different parts of the UK. It also recommends that the Office for Statistics Regulation review and publish a report on the adequacy of UK-wide comparable data, by themes. This report forms our response to this recommendation.
• In January 2025, the first UK Statistics Assembly was held in response to the Independent Review of the UK Statistics Authority. The report from the assembly sets out four high-level priorities, two of which are related to improving the comparability of data and statistics:

• • Priority 1: Re-invigorate sustained and effective user engagement, in which official statistics producers take a lead in understanding the needs for statistics and curating relevant sources, to help answer the questions that the public, businesses, local government, the media and academics, as well as policymakers have about the economic, social and environmental situation. This would also help understand and increase the value of statistics.
  • Priority 4: Recognise the needs for UK-wide statistics and advocate for, and support, harmonised data where desirable.

These reviews, and the views of users as recorded in the Statistics Assembly report, clearly set out the need for change. With the case for change made, this review focuses on providing recommendations and a framework that will help the UK statistical system address shortcomings in its ability to meet user needs for UK-wide comparable statistics and data on priority areas.

Given the long-running and complex nature of achieving comparable statistics, our recommendations are challenging, and they will require careful thought and oversight to successfully deliver. But in our view, they are all necessary to the drive the change highlighted by the PACAC report, the Lievesley review and, importantly, the users of statistics.

Approach of this review

Throughout our review, we build on the evidence base set out by relevant published reviews, our existing regulatory work and the stakeholder views captured at the UK Statistics Assembly. We also held semi-structured interviews with the Chief Statisticians in Scotland, Wales and Northern Ireland, and the Cabinet Office Union and Devolution Directorate. Finally, we spoke with the Office for National Statistics’ UK-wide, coherence and international teams and with representatives from the UK, Wales and Scotland parliamentary libraries to understand their needs for UK-wide comparable data.