The head of the Institute for Fiscal Studies on how damned lies get served up with statisticsby Paul Johnson / February 17, 2018 / Leave a comment
I trade in numbers, and am passionate about them. From crime rates to the climate, we need them to describe and make sense of the world around us. But I’ve also learned to be very cautious in their company. They don’t just help us to interpret the world, they can be powerful enough to change it too—and not always for the better.
A focus on one number, a shock balance of trade deficit that was published three days before a general election, is said to have done for Harold Wilson’s premiership in 1970. A particular measure of public borrowing caused the British government to bring in the IMF to bail it out in 1976. More recently, a net immigration figure in June 2016 played a role in the EU referendum decision, as of course did the most famous number of recent years: the £350m a week that we supposedly send to Europe.
Numbers, then, can and do disrupt the course of political history—that’s real power. With that power comes danger, especially where numbers are arbitrary or misleading, which is—in fact—what all those examples of politically powerful numbers were. That alarming trade deficit, released in the run-up to the 1970 general election, was puffed up by a one-off purchase of two jumbo jets, not by any underlying economic problem. The borrowing figures that led directly to the IMF intervention of 1976 were later revised down. Net immigration figures can be driven as much by the numbers of retired Brits moving to the Costa del Sol as they are by the thing that many voters actually worried about, the numbers of migrants coming to the UK for work. As for £350m a week, the less said the better.
Numbers don’t even have to be wrong to mislead. They just have to distract attention from other things that do matter, but can’t be counted or aren’t included in one particular figure. We go through fashions of fetishising particular measures—trade deficits in the 1970s, money supply in the 1980s, public sector borrowing more recently—to the exclusion of all else, crowding important information out of the debate.
Don’t get me wrong—the great power of numbers is often to the good. Huge extra spending on the health service was driven by knowledge of how many people were waiting unconscionable periods of time for an operation, information that had to…