FOI reference: FOI-2024-1824
You asked
It has recently emerged that the ONS has changed the manner in which it records excess deaths. As a result, the excess deaths figures which have been alarming for the last few years (even though being ignored by the government and mainstream media) are now looking a lot less worrying. This is at odds with other statistical outlets, including Our World in Data.
Under the Freedom of Information Act, I would be grateful if you could please advise:
i) what changes to the calculation of excess deaths have been made; and
ii) the rationale behind that.
I would also be grateful if you could provide copies of any emails, other correspondence or notes/minutes of requests received from any other agency on the subject which may have had an influence on the ONS' decision to change the calculation.
We said
Thank you for your request.
i) The key features of our new methodology for estimating the number of excess deaths in the UK are that:
Population growth is taken into account (all else being equal, we should expect more deaths among larger populations)
Population ageing is taken into account (all else being equal, we should expect more deaths among populations where a bigger share of the population is elderly)
Trends in population mortality rates are taken into account (all else being equal, we would expect fewer deaths in populations that are generally experiencing long-term improvements and more deaths in populations experiencing deteriorations in underlying health)
Individual weeks and months that were substantially affected by the immediate mortality impact of the pandemic are removed from the data when estimating expected deaths in subsequent periods, whereas the previous approach excluded data for the whole of 2020 (but not other pandemic-affected years)
Full details of the methodology can be found in our article published on 20 February 2024, and are summarised in a National Statistical blog post and a short explanatory video.
ii) Our previous methodology did not take account of the growth and ageing of the UK population; nor did it reflect recent trends in population mortality rates, which were generally falling until 2011 before levelling off until the onset of the pandemic. Accelerating population growth, particularly among people aged 70 years or older, during the COVID-19 pandemic (see Figure 3 in our article) provided an impetus to instigate this methodological development work.
This methodological change was the result of a complex project spanning 14 months and involving a number of different organisations. During this time, emails and notes have accumulated from a core team of eight Office for National Statistics staff members, plus several others who offered input into aspects of the work. A sample taken from one individual's mailbox brought up c.600 emails spanning across three months. If we multiply this by the number of staff members over a 14-month period, we would potentially be looking at the search for, location, extraction, and collation of tens of thousands of emails, in addition to meeting notes, to fulfil your request.
Therefore, the time taken for us to process your request would be in excess of the 24- working hour limit for FOI requests, and Section 12 of the Freedom of Information Act 2000 (FOIA) is engaged.