Some notes on excess mortality

As I prepared for an interview, I wrote notes on excess deaths.

Anthony B. Masters


Excess deaths are deaths from all causes above a baseline. That baseline often represents an expected number of deaths.

Different institutions use different baselines:

Excess death calculations differ through choices of periods and baselines.

Where can I find data on excess mortality?

There many institutions collating COVID-19 surveillance deaths. There is no single source for frequent all-cause mortality.

The World Bank calculates annual crude death rate per 1,000 people for countries. The United Nations Statistics Divisions publishes annual death statistics. The latest year in these datasets is 2019.

There are two teams of researchers collating weekly and monthly mortality figures.

News organisations, such as The Economist and The Financial Times, use these two sources and collate other mortality data.

Why do we need to look at excess mortality?

For public health agencies, COVID-19 surveillance deaths have specific definitions. Those definitions differ between countries, which makes for challenging comparisons. Definitions can also differ within countries too: with the USA and UK publishing aggregate statistics.

Timeliness matters more for surveillance numbers than completeness. It is useful to look at deaths from all causes, to circumvent labelling problems.

A major limitation is mortality statistics are not available for all countries. The UN Statistics Division estimates some countries have under half coverage of death registrations. Some places do not have sufficient death reporting systems to give accurate counts.



Anthony B. Masters

This blog looks at the use of statistics in Britain and beyond. It is written by RSS Statistical Ambassador and Chartered Statistician @anthonybmasters.