Why Pandemic Modelling Is So Hard

If you've been following the news, you'll likely have seen widely varying estimates of the severity of the current pandemic. That isn't because scientists and epidemiologists don't know what they're doing; it's because it's really difficult to get good, reliable data to base the models on.

Tom Chivers is a freelance British science writer who has written the best explanation I've seen yet on how these models are created and why they vary so widely.

I want to talk about the models, and what they tell us, because the outputs of these models drive the government’s response — and thousands of lives could turn on them. It’s important, therefore, that we understand them, and why the numbers they give us are so different. These figures led Peter Hitchens, the Mail on Sunday columnist, to complain that the number of deaths has jumped around from 500,000 to 20,000, to 5,000. I can see why people are confused, if they just think “the models” are taking the same numbers and spitting out these weirdly different results.

But first, I want to talk about something much simpler. It’s the question that many of us, I’d say, most want to know, when we’re anxiously thinking about Covid-19 and ourselves and our loved ones. That is: if someone gets the disease, how likely are they to die?

Reading this article isn't going to make you feel any better (it may make you feel more unsettled) but at least you'll know what's going on, and why.