The best ways to compare deaths by country

Robert Cuffe

BBC head of statistics

Statisticians advise not to use the daily reported figures. They prefer an analysis that looks at all deaths, but takes account of the average age in a country.

What's wrong with the daily figures?

The definition changes across countries - some only include hospital deaths, some include care homes too.

Belgium includes deaths where Covid-19 is suspected to have contributed, for example, whereas the UK only includes people who tested positive for Covid-19.

When every country counts things differently, statisticians turn to a different measure - with a simpler definition.

Counting 'excess deaths'

If you look at all deaths in a country, irrespective of cause, you will capture the deaths missed by lab testing, misdiagnosed deaths and  deaths caused by the strain the virus puts on our society. Of course, you'll capture the heart attacks and car accidents that might have happened anyway.

But the total number of deaths registered in a week normally follows a predictable pattern.

It has shot up since the end of March, running far higher than the previous weeks or what would be expected at this time of year. These extra deaths are largely attributed to the pandemic.

And it's these extra or “excess” deaths, the difference between the number we normally see and what we're seeing at the moment, that statisticians use to capture the true toll of the coronavirus.

Adjust for age

You also need to account for how old the population is, because the coronavirus is most dangerous to older people. So you'd expect to see more excess deaths in Italy, where the average age is 47, than in Ireland, where it's 37.

Once you've done that calculation, known in the jargon as "excess all cause mortality adjusted for age", then you get a clearer picture of how different nations are doing.

BBCCopyright: BBC