Dear Ed,

I’m writing to inform you of a change we are making to the Welsh referral to treatment (RTT) waiting list statistics to improve the relevance and timeliness of these high-profile figures. These statistics are included in the monthly statistical release NHS activity and performance summary.

There is a great deal of public interest in NHS waiting list data, particularly around long waiting times. The official measures are published with a lag of around seven weeks, meaning for example, June’s final figures will be released on 21 August. Given the attention on these statistics, there is public value in making data on this topic available earlier where possible.

Statisticians in the Welsh Government have explored how to produce more timely waiting list estimates based on extracts of the data taken earlier than those used to produce the official measures. We have established that these data provide a reliable indication of the eventual official statistics. As a result, from the August publication onwards, we will include provisional estimates for the preceding month on the total number of RTT pathways waiting (“the waiting list”) and those waiting more than one and two years. For example, for the August publication this will mean that provisional estimates will be provided on NHS performance during July, alongside final official figures for June.

We are focusing on these specific measures as Welsh Ministers have set targets relating to the overall size of the waiting list and for waits of two years or more. They are therefore the focus of much public comment on the statistics. These two statistics are typically presented alongside one year waits, so in order to provide a coherent package of statistics, we will additionally provide a provisional estimate of one year waits.

These three figures are a small subset of the full range of breakdowns we publish with the official data. They will be presented as provisional, as they may change to some extent before the final official statistics are published the following month. However, I believe they will provide a reliable and timely estimate which will meet user needs. I consider releasing these figures is in the public interest because it will support the NHS and Welsh Ministers’ ability to track activity and transparently communicate progress against the Welsh Government commitments, and enable scrutiny of the NHS and Welsh Government’s performance in this high-profile policy area.

In the run up to the Senedd election in May 2026, it is likely that there will be public interest in timely measurement of other government targets. This may necessitate new approaches such as using management information, projections or forecasts to complement existing official statistics. Where this need arises, I will consider applying the following criteria to help determine whether alternative methods could be used:

• The relative profile, value or utility of the measures, either operationally or in the context of public debate
• The reliability and accuracy of alternative data sources
• The appropriateness of the methods used to produce the figures
• The ability to communicate the strengths and limitations of these data and methods
• The proportionality of the burden on data suppliers and statistics producers
• Going forward we will monitor the usage and reliability of the provisional waiting list figures, as well as monitor and respond to user need for timely statistics for other government targets.

Stephanie Howarth
Prif Ystadegydd
Chief Statistician

Related Links:

Ed Humpherson to Stephanie Howarth: Timely Waiting List Statistics