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.

Or:

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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Theresa May "indifferent" towards Northern Ireland, says Alliance leader Naomi Long

The non-sectarian leader questioned whether the prime minister and James Brokenshire have the “sensitivity and neutrality” required to resolve the impasse at Stormont.

Theresa May’s decision to call an early election reflects her “indifference” towards the Northern Ireland peace process, according to Alliance Party leader Naomi Long, who has accused both the prime minister and her Northern Ireland secretary James Brokenshire of lacking the “sensitivity and neutrality” required to resolve the political impasse at Stormont.

In a wide-ranging interview with the New Statesman, Long – who is running to regain her former Belfast East seat from the DUP for her non-sectarian party in June – accused the Conservatives of “double messaging” over its commitment to Northern Ireland’s fragile devolution settlement. The future of power-sharing province remains in doubt as parties gear up for the province’s fourth election campaign in twelve months.

Asked whether she believed the prime minister – who has been roundly criticised at Stormont for her decision to go to the country early – truly cared about Northern Ireland, Long’s assessment was blunt. “We have had no sense at any time, even when she was home secretary, that she has any sensitivity towards the Northern Ireland process or any interest in engaging with it at all... It speaks volumes that, when she did her initial tour when she was prime minister, Northern Ireland was fairly low down on her list.”

The timing of the snap election has forced Brokenshire to extend the deadline for talks for a fourth time – until the end of June – which Long said was proof “Northern Ireland and its problems were not even considered” in the prime minister’s calculations. “I think that’s increasingly a trend we’ve seen with this government,” she said, arguing May’s narrow focus on Brexit and pursuing electoral gains in England had made progress “essentially almost impossible”.

“They really lack sensitivity – and appear to be tone deaf to the needs of Scotland and Northern Ireland,” she said. “They are increasingly driven by an English agenda in terms of what they want to do. That makes it very challenging for those of us who are trying to restore devolution, which is arguably in the worst position it’s been in [since the Assembly was suspended for four years] in 2003.”

The decisive three weeks of post-election talks will now take place in the weeks running up to Northern Ireland’s loyalist parade season in July, which Long said was “indicative of [May’s] indifference” and would make compromise “almost too big an ask for anyone”. “The gaps between parties are relatively small but the depth of mistrust is significant. If we have a very fractious election, then obviously that timing’s a major concern,” she said. “Those three weeks will be very intense for us all. But I never say never.”

But in a further sign that trust in Brokenshire’s ability to mediate a settlement among the Northern Irish parties is deteriorating, she added: “Unless we get devolution over the line by that deadline, I don’t think it can be credibly further extended without hitting James Brokenshire’s credibility. If you continue to draw lines in the sand and let people just walk over them then that credibility doesn’t really exist.”

The secretary of state, she said, “needs to think very carefully about what his next steps are going to be”, and suggested appointing an independent mediator could provide a solution to the current impasse given the criticism of Brokenshire’s handling of Troubles legacy issues and perceived partisan closeness to the DUP. “We’re in the bizarre situation where we meet a secretary of state who says he and his party are completely committed to devolution when they ran a campaign, in which he participated, with the slogan ‘Peace Process? Fleece Process!’ We’re getting double messages from the Conservatives on just how committed to devolution they actually are.”

Long, who this week refused to enter into an anti-Brexit electoral pact with Sinn Fein and the SDLP, also criticised the government’s push for a hard Brexit – a decision which she said had been taken with little heed for the potentially disastrous impact on Northern Ireland - and said the collapse of power-sharing at Stormont was ultimately a direct consequence of the destabilisation brought about by Brexit.

 Arguing that anything other than retaining current border arrangements and a special status for the province within the EU would “rewind the clock” to the days before the Good Friday agreement, she said: “Without a soft Brexit, our future becomes increasingly precarious and divided. You need as Prime Minister, if you’re going to be truly concerned about the whole of the UK, to acknowledge and reflect that both in terms of tone and policy. I don’t think we’ve seen that yet from Theresa May.”

She added that the government had no answers to the “really tough questions” on Ireland’s post-Brexit border. “This imaginary vision of a seamless, frictionless border where nobody is aware that it exists...for now that seems to me pie in the sky.”

However, despite Long attacking the government of lacking the “sensitivity and neutrality” to handle the situation in Northern Ireland effectively, she added that Labour under Jeremy Corbyn had similarly failed to inspire confidence.

“Corbyn has no more sensitivity to what’s going on in Northern Ireland at the moment than Theresa May,” she said, adding that his links to Sinn Fein and alleged support for IRA violence had made him “unpalatable” to much of the Northern Irish public. “He is trying to repackage that as him being in some sort of advance guard for the peace process, but I don’t think that’s the position from which he and John McDonnell were coming – and Northern Irish people know that was the case.” 

Patrick Maguire writes about politics and is the 2016 winner of the Anthony Howard Award.

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