Dear Mr Wragg,

Thank you very much for the opportunity to give evidence to your Committee as part of the Transforming the UK Evidence Base inquiry on 6 February. I enjoyed the session and I hope that you found my evidence useful.

I am writing to provide some supplementary evidence related to comparability of statistics across the UK.

During the session, I set out the expectations we have as the Office for Statistics Regulation for statistics producers on questions of comparability. I emphasised that where there are questions from users around how to compare the performance of public services across the UK, producers in the four nations should recognise and seek to meet that need.

Meeting that need is not straightforward. As I explained, the configuration of public services will probably be different, because of different policy and delivery choices that have been made by the different governments. This is consistent with the concept of devolution, but it does mean that administrative data may be collected and reported on different bases.

However, it is not in our view sufficient for producers to simply argue that statistics are not comparable. They should recognise the user demand, and explain how their statistics do, and do not, compare with statistics in other parts of the UK. And they should also undertake analysis to try to identify measures that do allow for comparison.

A very good example of this approach is provided by statisticians in the Welsh Government. Their Chief Statistician published two blogs on the comparability of health statistics, Comparing NHS performance statistics across the UK and Comparing NHS waiting list statistics across the UK. These blogs recognise the user demand and provides several insights to enable users to make comparisons of NHS performance.

In addition, the Welsh Government’s monthly NHS performance release also highlights what can, and cannot, be compared. For example, it shows that in November 2023, there were approximately 22 patient pathways open for every 100 people, while for England, the figure in November was 13 pathways for every 100 people. More generally, I would commend the Chief Statistician’s blogs as a good example of providing guidance and insight to users across a wide range of statistical issues.

During my evidence session I also mentioned the approach taken by NHS England to highlight the most comparable accident and emergency statistics. NHS England provide a Home Nations Comparison file for hospital accident and emergency activity each year.

More generally, the ONS is leading comparability work across a range of measures. In addition to work on health comparability, they have produced very good analysis of differences in fuel poverty measurement across the four nations.

I hope this additional evidence is useful. I would like to reiterate that these examples show statisticians recognising the core point – that there is a user demand for comparability and that they are taking steps to meet that demand.

Yours sincerely,

Ed Humpherson

Director General for Regulation