Understanding risk today: the art of statistics

Sunday 3 November, 16:0017:15, Frobisher Auditorium 1Science and society

Which is a greater risk, eating bacon sandwiches or going to university? Be warned, both have been accused of increasing your risk of different cancers by 19 per cent. But should we believe these numbers, and should we care anyway? Press, public and policymakers all routinely misunderstand the science and mathematics of risk, something Professor David Spiegelhalter is trying to combat at the Winton Centre for Risk and Evidence Communication at Cambridge University.

In his latest book, The Art of Statistics, Professor Spiegelhalter guides the reader through the essential principles we need in order to derive knowledge from data. Drawing on real-world problems to introduce conceptual issues, he shows us how statistics can help us determine the luckiest passenger on the Titanic, whether serial killer Harold Shipman could have been caught earlier, and if screening for ovarian cancer is beneficial. The book is packed with statistical conundrums and how we might try to solve them. How many trees are there on the planet? Do busier hospitals have higher survival rates? Why do old men have big ears?

But understanding statistics is only half the battle. The trouble with risk goes far beyond society’s often-shaky grasp of numbers. When risks and statistics are expressed as probabilities, they can at least be understood rationally and managed. But society has drifted away from a probabilistic approach to risk, asking how likely something is to happen, towards a possibilistic instinct, where anything that could possibly happen must be considered. Possibilistic risks are always there as a vague nagging anxiety, however unlikely.

And once all the worst-case scenarios have been identified, risk-averse businesses, political groups and governments tend to organise around them. Governments can declare climate emergencies and activists demand that society be reorganised around existential threats. At a time when society seems to lack confidence in the future and seems fearful of change, we now tend to see everything through the prism of risk. Businesses often seem to spend more time managing their risk register than their profit margins.

Is it possible to rescue a rational understanding of the world when ‘what if?’ thinking so dominates public discussion? What are the consequences if the worst-case scenario becomes the focus of society’s attention? Can understanding statistics better help?