David Spiegelhalter: How to be a coronavirus statistics sleuth

During the covid-19 pandemic we’ve been bombarded with stats – making it more important than ever to understand what the numbers can and can’t tell us

By David Spiegelhalter

THERE IS a quote from Nate Silver about statistics which I think is very nice: “The numbers have no way of speaking for themselves. We speak for them, we imbue them with meaning.” You can’t just collect some data and it’ll tell you the answer. There is an art to trying to extract information, knowledge and understanding from data, and even in choosing what data to collect. It’s something we’ve all been dealing with over the past few months with covid-19: can we believe these numbers? What do they mean?

Now if this were a live audience, I’d be asking how many people have done stats courses. If people put their hand up, I’d ask how many people actually enjoyed them, and most of the hands would go down. That makes me upset. I love statistics, I think it’s great. But it has tended to be taught in the past as a series of formulae and tests and regression and things like that.

My book The Art of Statistics takes a very different approach. It spends a lot of time on problem solving, on things like: what are you trying to do? Is this data suitable for what you’re trying to answer? What can we conclude from it? It’s amazing how far you can get without ever doing any fancy statistical methods or using probability theory or the sample distribution of the sample mean and all this sort of stuff we all had to endure – and which I’ve always taught, of course.

The key is what is called the “data cycle”. You don’t start off with data, you …