See if you can work out the major statistical flaw in this Telegraph piece on marriage

It's not that hard…

It's bad stats Saturday, it seems. Before we start, see if you can work out for yourself what statistical stumble the Telegraph has made which renders this piece, headlined Almost no couples with children who stay unmarried stay together, study claims, entirely worthless. Go on, click through, we'll still be here.

Back? Hopefully you'll have been able to work out the main claim of the piece, which is that:

A study by the Marriage Foundation calculates that cohabiting couples who have children are more than twice as likely to split up as those who had tied the knot beforehand.

But of those who do not then go on to get married after having children, only a handful will still be together by the time the child is 16, it claims. [Emphasis mine]

It's a bold claim, and would certainly be a valuable fact for those who worry about the death of the "traditional" family to be able to point to. Unfortunately, it isn't true.

Further down the piece, we find the evidence behind the claim:

The report, which analyses figures from the Office for National Statistics, found that 93 per cent of couples whose relationships are still intact by the time their child is a teenager are married.

It calculated that out of a typical group of 100 16-year-olds, 45 of them would have experienced a family split, while 55 would still be living with both parents.

But only four of the 100 teenagers would have unmarried parents who are still together by the time they are 16. [Emphasis mine again]

In other words, of 100 sixteen-year-olds, only four have unmarried parents living together. That is, indeed, "only a handful" – but it is not a handful of "of those who do not go on to get married after having children". That figure is not given in the Telegraph report at all, and it's crucial. Without knowing what proportion of sixteen year olds were born to parents who were unmarried but living together, we can't know whether 4 per cent still living together is high, or low.

To find that out, we need to go to the original report, which claims that "out of the 47 per cent of children born to unmarried parents today… just 11 per cent will reach their 16th birthday with both parents intact and unmarried".

In other words, the survival rate of unmarried couples with children is over twice what the Telegraph implies; rather than 4 per cent, it is 11 per cent.

But there's something else as well. As the report says, "the rest will either marry or split up". In other words, a chunk of unmarried parents go on to marry before their child turns sixteen. That is also missed by the Telegraph's write up.

That is, where the paper writes that:

Only four of the 100 teenagers would have unmarried parents who are still together by the time they are 16.

It should actually read:

Only four of the 100 teenagers would have unmarried parents who are still together and still unmarried by the time they are 16.

And all of this stems from a report which is fundamentally based on assuming that patterns of marriage and cohabitation which were true for couples with children born in 1986 are still true for couples with children born in 2009. That's not something I'd stake money on; in case no-one noticed, we've had some pretty major changes to marriage recently.

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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In defence of expertise: it’s time to take the heart out of “passionate” politics

What we need is cool logic.

We are living through a bonfire of the experts. During the EU referendum campaign, Michael Gove explained that people had had enough of them. A few weeks later, his fellow Tory MPs took him at his word and chose a relative ingénue to run against Theresa May.

After declaring for Andrea Leadsom in the Tory leadership race, Michael Howard was asked whether it might be a problem that she had never held a position higher than junior minister. Howard, whose long career includes stints as home secretary and opposition leader, demurred: “I don’t think experience is hugely important.”

Even in this jaw-dropping season, that comment caused significant mandibular dislocation. I thought: the next Tory leader will become prime minister at a time of national crisis, faced with some of the UK’s most complex problems since the Second World War. If experience doesn’t matter now, it never does. What does that imply about the job?

Leadsom’s supporters contended that her 25 years in the City were just as valuable as years spent at Westminster. Let’s leave aside the disputed question of whether Leadsom was ever a senior decision-maker (rather than a glorified marketing manager) and ask if success in one field makes it more likely that a person will succeed in another.

Consider Ben Carson, who, despite never having held elected office, contested the Republican presidential nomination. He declared that Obamacare was the worst thing to happen to the United States since slavery and that Hitler may have been stopped if the German public had been armed. Yet Carson is not stupid. He is an admired neurosurgeon who pioneered a method of separating conjoined twins.

Carson is a lesson in the first rule of expertise: it does not transfer from one field to another. This is why, outside their domain, the most brilliant people can be complete dolts. Nevertheless, we – and they – often assume otherwise. People are all too ready to believe that successful generals or entrepreneurs will be good at governing, even though, more often than not, they turn out to be painfully inept.

The psychologist Ellen Langer had her subjects play a betting game. Cards were drawn at random and the players had to bet on whose card was higher. Each played against a well-dressed, self-assured “dapper” and a shabby, awkward “schnook”. The participants knew that it was a game of chance but they took more risks against the schnook. High confidence in one area (“I’m more socially adept than the schnook”) irrationally spilled over into another (“I’ll draw better cards”).

The experiment points us to another reason why we make poor judgements about competence. We place too much faith in social cues – in what we can see. As voters, we assume that because someone is good at giving a speech or taking part in a debate, they will be good at governing. But public performance is an unreliable indicator of how they would cope with running meetings, reading policy briefs and taking decisions in private. Call it the Boris principle.

This overrating of the visible extends beyond politics. Decades of evidence show that the job interview is a poor predictor of how someone will do in the job. Organisations make better decisions when they rely on objective data such as qualifications, track record and test scores. Interviewers are often swayed by qualities that can be performed.

MPs on the Commons education select committee rejected Amanda Spielman, the government’s choice for the next head of Ofsted, after her appearance before them. The committee didn’t reject her because she was deficient in accomplishments or her grasp of education policy, but because she lacked “passion”. Her answers to the committee were thoughtful and evidence-based. Yet a Labour MP told her she wasn’t sufficiently “evangelical” about school improvement; a Tory asked her to stop using the word “data” so often. Apparently, there is little point in being an expert if you cannot emote.

England’s football team is perennially berated in the media for not being passionate enough. But what it lacks is technique. Shortly before Wales played England in the European Championship, the Welsh striker Gareth Bale suggested that England’s players lacked passion. He knew exactly what he was doing. In the tunnel before kick-off, TV cameras caught the English goalkeeper Joe Hart in a vessel-busting frenzy. On the pitch, Hart allowed Bale to score from an absurdly long range because he was incapable of thinking straight.

I wish there were less passion in politics and more cool logic; less evangelism and more data. Unthinking passion has brought the Labour Party to its knees and threatens to do the same to the country. I find myself hungering for dry analyses and thirsting for bloodless lucidity. I admire, more than ever, those with obscure technical knowledge and the hard-won skills needed to make progress, rather than merely promise it.

Political leadership is not brain surgery but it is a rich and deep domain. An effective political leader needs to be an expert in policy, diplomacy, legislative process and how not to screw up an interview. That is why it’s so hard to do the job well when you have spent most of your time in boardrooms or at anti-war rallies.

If democratic politicians display contempt for expertise, including their own, they can hardly complain if those they aspire to govern decide to do without the lot of them. 

Ian Leslie is a writer, author of CURIOUS: The Desire to Know and Why Your Future Depends On It, and writer/presenter of BBC R4's Before They Were Famous.

This article first appeared in the 21 July 2016 issue of the New Statesman, The English Revolt