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DID you realise that schools in the US have been getting steadily safer, despite terrible incidents such as the massacre at Columbine? That statistic – that schools are getting safer – may feel like a comfort blanket of truth in an uncertain world. In More Damned Lies and Statistics Joel Best breaks the bad news that this is false comfort. He has bad news for anyone who wants to misuse statistics, especially in the sphere of public policy, often a stronghold of bafflement.

Statistics are social constructions and the problems begin when people decide what is important enough to measure. As Best sees it, ignorance is probably worse than dishonesty as a source of numerical mayhem. It is true that humans share 98 per cent of their genes with chimpanzees, he points out, but does that tell us that we are like them? Real problems, he cautions, are also very hard to measure well. How often do hospitals make fatal errors? Tricky, as the people in them are by definition unwell in the first place. Or suicide? One inquest’s accidental fall is another’s deliberate jump.

Best concludes that statistics should be taught as a social science, not as part of mathematics. In the meantime, he advises anyone seeing accounts of, say, a 10 per cent increase in the risk of a particular disease to pay no attention. Anything less than 200 per cent is just noise.