…you may think that the middle one – 1 in 1,000 – is the ‘biggest’ risk, since 1,000 is ‘bigger’ than the other numbers. For example, when comparing the following: Naturally, people can find this very confusing. The Understanding Uncertainty website has a useful animation that shows there are a staggering 2,845 ways to talk about a risk. But we can also say it happens ‘a quarter of the time’, or ‘25 per cent of the time’ (we’ll come to percentages later). That’s an important thing to remember about risk – it tells us about the chance of something happening, but it’s not a guarantee that it will.īut because risks tell us how many times an event would probably have happened, on average, out of all the chances it could have happened, there are lots of different ways of representing them.įor example, if something usually happens one time in every four – like drawing a Heart from a deck of cards – we can say it happens one in four times. But it’s also possible (in fact it’s more likely) that the card you pick won’t be a Heart. So if you pick a card at random, the chance or ‘risk’ that it will be a Heart is one in four. Simply put, the ‘risk’ of something happening is its chance of taking place.Ī quarter of the cards in a standard pack of playing cards are Hearts.

In this post we’ll explore the notion of risk, and some of the common pitfalls of taking headlines involving risk at face value. They tell us how much more, or less, likely the disease is in one group, compared to another.īut crucially, they don’t tell us anything about the overall likelihood of any of these things happening at all – what’s known as the absolute risk. They’re all statements of the relative risk of developing cancer.

“ One drink a day increases breast cancer risk by 5% ”.

“ CT scans in childhood can triple the chance of developing brain cancer ”.

“ People who use sunbeds are 20% more likely to develop malignant melanoma ”.

Realtive risk incrase