In our latest blog, our Head of Private Office discusses comparability of data across the UK, which was topical at a recent Public Administration and Constitutional Affairs Select Committee…

When Ed Humpherson, Director General of OSR gave evidence recently to the Public Administration and Constitutional Affairs Select Committee (PACAC), one of the issues raised at the session was comparability of data across the UK.

For context, in 2023 the Committee launched their inquiry focused on transforming the UK’s statistical evidence base (you can read more about the issue of transparency that Ed explored with the Committee in his earlier ). Ed was the last witness to give evidence to the inquiry and the issue of comparability came up in several of the previous sessions with other witnesses.

Meeting user needs is not always straightforward, especially when that need is comparing data across the UK. As Ed explained to the Committee, the configuration of public services will probably be different across the UK, because of different policy and delivery choices that have been made by the distinct devolved governments. This is the nature of devolution, but a consequence is that administrative data may be collected, and reported, on different bases.

In our view, though, it is not sufficient for producers to simply state that statistics are not comparable. In line with the Code of Practice for Statistics 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 producers should undertake analysis to try to identify measures that do allow for comparison, or to provide appropriate narrative that helps users understand the extent of comparability.

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 set out additional analysis carried out by analysts at the Welsh Government in collaboration with analysts in NHS England to accurately understand the differences between the definitions of NHS waiting times between the two nations. The blogs then adjust Wales’s own figure to produce an additional measure which is broadly comparable with that of England. More generally, the Chief Statistician’s blogs are a good example of providing guidance and insight to users across a wide range of statistical issues.

In addition, the Welsh Government’s monthly NHS performance release also highlights what can, and cannot, be compared.

And it’s not just the Welsh Government. During the evidence session Ed 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. Since the session, statisticians from the across the UK have jointly produced analysis of the coherence and comparability of A&E statistics and advice on how they should and should not be compared, published on 28 February.

More generally, statisticians across the UK are undertaking comparability work across a range of measures. It is also important to recognise that at the level of health outcomes – things like smoking rates and life expectancy – figures are less related to the delivery of NHS services and are therefore more readily comparable. In addition to work on health comparability, statisticians have examined other cross-UK issues. For example, there is also very a good analysis of differences in fuel poverty measurement across the four nations.

So, whilst we at OSR, of course, champion comparability of data and believe it should be a priority for government, we are not alone. The examples in this blog demonstrate that statisticians are recognising, and taking steps to meet, user demand for comparability. And we have written to the Committee to highlight the activities that are described here.

We are looking forward to the results of the enquiry and their recommendations on how we can all have a role in transforming the UK statistical evidence base for the better.


Related correspondence:

Ed Humpherson to William Wragg MP: Supplementary evidence to the Public Administration and Constitutional Affairs Committee