Government Actuary's Department
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Estimating excess deaths - new methodology

We peer reviewed a draft report on a new methodology for estimating excess deaths. The ONS publication compared old and new methodologies.

The Government Actuary’s Department (GAD) peer reviewed a draft version of a publication on new methodology for estimating excess deaths in the UK.

Excess mortality is the difference between the observed number of deaths in a particular period and the number of deaths that would have been expected in that period, based on historical data.

Draft publication review

The report, from the Office for National Statistics (ONS) contains estimates for excess deaths for 2023. GAD reviewed the model article ahead of its publication. The article explains the new approach and provides a comparison of estimates from the new and current methods for recent years.

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New method

The ONS reported that the new methodology means in the UK there were 10,994 excess deaths last year. This is 20,448 fewer than the estimate using the current method.

Differences between the new and current methods mean that:

  • the expected number of deaths used in the calculation of excess mortality is estimated from age-specific mortality rates rather than death counts
  • trends in population size and age structure are taken into account
  • it accounts for trends in population mortality rates
  • estimates, on an annual basis, indicate 76,412 excess deaths in the UK in 2020, compared with 84,064 (estimated by the old method)

The new and old methods estimate similar numbers of excess deaths during the COVID-19 pandemic.

Collaboration and development

This methodology was developed in collaboration with several organisations. These included the Office for Health Improvement and Disparities, the UK Health Security Agency and the Continuous Mortality Investigation.


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