The reason, he explains, is that if a country with a large population gets an outbreak in a specific region, like Wuhan in China, New York in the US or Lombardy in Italy, then it is not interesting how many people live throughout the country.

"In that case, we should compare with the population in the specific region," says Tom Britton, professor of mathematical statistics at Stockholm University.

The slope shows the rate of increase

But there are more reasons why the number gives a better picture than the proportion.

- There are two things we need to keep in mind. How far a country has come in its outbreak and at what rate it is increasing. The pace is seen on the slope of the curve and then that is the number that applies, says Tom Britton.

How far a country has come in the outbreak is also important, so in order to compare, you have to look at where the countries were on the curve when they reached the same day.

"Some countries would not join"

According to Tom Britton, you should also not put Day 1 at the first death of a country because it is very random at first. SVT's graph, which is based on statistics from Johns Hopkins University, begins at the tenth death.

- It's better. The 30th or 50th deaths might have been even better, but the problem then is that some countries would not be at all. What is interesting is to see the rate of increase once it has started to take off.

"The disadvantage is if it takes off again"

If you compare Sweden with our Nordic neighboring countries, we are higher in both number and proportion, even though they take into account that they have not progressed as far as us in development. Denmark's curve initially grew rapidly, but began to level out fairly early compared to Sweden's, while the outbreaks do not appear to have picked up in the same way in Norway and Finland. According to Tom Britton, this is because we have chosen different strategies.

- If you do a lot, few people die, but the disadvantage is that there is a great risk that it will take off again when you release the restrictions. In areas that have had a larger outbreak, more people will be immune, so you do not have to be so worried when, for example, the school starts again this fall, he says.