Why are we so in thrall to numbers? An odd question for a financial newspaper perhaps. But an important one. As Chinese statisticians were embarrassed this week by a $250bn discrepancy (10 per cent) between provincial and centrally calculated half-year gross domestic product figures, we should remind ourselves what numbers tell us and what they don’t. On occasion, they do more harm than good.

We are familiar with the idea that numbers can be manipulated. Whether it was Benjamin Disraeli, the British prime minister, or Mark Twain, the American wit, who said it first, everyone knows the bon mot: “There are lies, damned lies, and then there are statistics.” Numbers can tell a story, but whose story do they tell?