Dear Mr Clark,
On 2 March 2022, I gave oral evidence to the Science and Technology Committee. In my evidence in response to a question about the approach to measuring excess deaths I referred to the Office for National Statistics (ONS) approach, stating that: “For the five-year rolling average excess deaths, ONS has decided for 2022 to drop 2020 from the five-year calculation… It is 2016, 2017, 2018, 2019 and 21, and it has dropped 2020 because 2020 had such an unusual peak of deaths.”
I wanted to clarify that there are a number of ways to measure excess deaths, that is, the difference between the expected number of deaths and the actual number of deaths in a given period of time. The ONS headline approach, shown in the weekly deaths publication is as I described above and has been agreed across the devolved administrations. ONS publications also refer to excess deaths based on the five-year average from 2015 to 2019. ONS has published a blog explaining more about its choice of five-year average.
As the ONS blog notes, more complex methods can also be used to calculate expected deaths. The Office for Health Improvement and Disparities (OHID) uses a more sophisticated modelling approach, taking into consideration the ageing population, differing mortality trends in subgroups of the population and variation in registrations around bank holidays. OHID developed a different method to that of ONS because it needed more accurate data for operational decision making during the pandemic. OHID continues to use the years prior to the pandemic (2015-2019) as the five-year baseline for its measure of excess deaths.
I would be happy to discuss this further if you would find it helpful.
Director General for Regulation