The risks of imprecision

When being half-right can be worse than being wrong.

Chris Dillow has a nice post up, "in praise of imprecision". He argues that, in far too many situations, we argue over tiny differences in estimates when the overall answer is basically known. What's GDP growth for last year? It's basically flat. Yet for all the arguments, you would think that the difference between -0.3 and -0.1 per cent – or even between -0.1 and 0.1 – was the difference between life and death.

He illustrates this with a few neat little guesstimates. For instance:

How much does welfare scrounging cost the economy? Guesstimate the number of scroungers. Guesstimate the value-added they'd contribute if they were working. Express as a proportion of GDP. For plausible values, it's a small number.


What impact will the small uprating in the minimum wage have on jobs? The adult rate will rise by 1.9%. Economists forecast inflation this year of 2.5%, so this is roughly a 0.6% real fall. Let's call the price-elasticity of demand for labour 1.5. The Low Pay Commission estimates (pdf) that 5.3% of jobs are around minimum wage ones. Multiply these three numbers together and we get 0.048%. Multiply by the number of jobs in the economy (29.73m) and we have roughly 14,000.That's roughly one-eleventh of the sampling variability of employment figures.

It's worth pointing out that the same idea has been applied pretty consistently to the claim that families with three generations of worklessness are a public policy problem. We don't know how many there are – and nor does the government, we now know – but study after study has suggested that the number is tiny.

There are only 15,000 households with two generations which have never worked, and a third of them are because the younger generation left full time education within the last year. On top of that, less than 1 per cent of young people have never worked by the age of 29, so the younger generation is normally the one most likely to pull a family out of worklessness. Whatever the number is, in other words, it's really, really small.

But it's important to note the downside to imprecision. The way common knowledge is disproved is rarely through wholesale upheaval. Instead, it's a gradual process of refinement: new estimates are put out, slightly lower than the old ones; then lower estimates still; and they get steadily lower, until suddenly you realise that the conventional wisdom was wrong.

It's a lot harder to turn an estimate of "recession" into an estimate of "growth" through gradual refinement than it is to turn an estimate of "-0.3 per cent" into one of "0.5 per cent". So there's more of a danger that we'll be stuck with half-truths.

But with that danger in mind, the absence of accepted imprecision is still keenly felt in Whitehall. Too frequently, "no statistics" is used to imply "we have no idea of the magnitude of this problem" – but that's not true. We actually know quite a lot, albeit imprecisely. The trick is acting on it.

Photograph: Getty Images

Alex Hern is a technology reporter for the Guardian. He was formerly staff writer at the New Statesman. You should follow Alex on Twitter.

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Michael Gove definitely didn't betray anyone, says Michael Gove

What's a disagreement among friends?

Michael Gove is certainly not a traitor and he thinks Theresa May is absolutely the best leader of the Conservative party.

That's according to the cast out Brexiteer, who told the BBC's World At One life on the back benches has given him the opportunity to reflect on his mistakes. 

He described Boris Johnson, his one-time Leave ally before he decided to run against him for leader, as "phenomenally talented". 

Asked whether he had betrayed Johnson with his surprise leadership bid, Gove protested: "I wouldn't say I stabbed him in the back."

Instead, "while I intially thought Boris was the right person to be Prime Minister", he later came to the conclusion "he wasn't the right person to be Prime Minister at that point".

As for campaigning against the then-PM David Cameron, he declared: "I absolutely reject the idea of betrayal." Instead, it was a "disagreement" among friends: "Disagreement among friends is always painful."

Gove, who up to July had been a government minister since 2010, also found time to praise the person in charge of hiring government ministers, Theresa May. 

He said: "With the benefit of hindsight and the opportunity to spend some time on the backbenches reflecting on some of the mistakes I've made and some of the judgements I've made, I actually think that Theresa is the right leader at the right time. 

"I think that someone who took the position she did during the referendum is very well placed both to unite the party and lead these negotiations effectively."

Gove, who told The Times he was shocked when Cameron resigned after the Brexit vote, had backed Johnson for leader.

However, at the last minute he announced his candidacy, and caused an infuriated Johnson to pull his own campaign. Gove received just 14 per cent of the vote in the final contest, compared to 60.5 per cent for May. 


Julia Rampen is the editor of The Staggers, The New Statesman's online rolling politics blog. She was previously deputy editor at Mirror Money Online and has worked as a financial journalist for several trade magazines.