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.

Photo: Getty
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Scotland's vast deficit remains an obstacle to independence

Though the country's financial position has improved, independence would still risk severe austerity. 

For the SNP, the annual Scottish public spending figures bring good and bad news. The good news, such as it is, is that Scotland's deficit fell by £1.3bn in 2016/17. The bad news is that it remains £13.3bn or 8.3 per cent of GDP – three times the UK figure of 2.4 per cent (£46.2bn) and vastly higher than the white paper's worst case scenario of £5.5bn. 

These figures, it's important to note, include Scotland's geographic share of North Sea oil and gas revenue. The "oil bonus" that the SNP once boasted of has withered since the collapse in commodity prices. Though revenue rose from £56m the previous year to £208m, this remains a fraction of the £8bn recorded in 2011/12. Total public sector revenue was £312 per person below the UK average, while expenditure was £1,437 higher. Though the SNP is playing down the figures as "a snapshot", the white paper unambiguously stated: "GERS [Government Expenditure and Revenue Scotland] is the authoritative publication on Scotland’s public finances". 

As before, Nicola Sturgeon has warned of the threat posed by Brexit to the Scottish economy. But the country's black hole means the risks of independence remain immense. As a new state, Scotland would be forced to pay a premium on its debt, resulting in an even greater fiscal gap. Were it to use the pound without permission, with no independent central bank and no lender of last resort, borrowing costs would rise still further. To offset a Greek-style crisis, Scotland would be forced to impose dramatic austerity. 

Sturgeon is undoubtedly right to warn of the risks of Brexit (particularly of the "hard" variety). But for a large number of Scots, this is merely cause to avoid the added turmoil of independence. Though eventual EU membership would benefit Scotland, its UK trade is worth four times as much as that with Europe. 

Of course, for a true nationalist, economics is irrelevant. Independence is a good in itself and sovereignty always trumps prosperity (a point on which Scottish nationalists align with English Brexiteers). But if Scotland is to ever depart the UK, the SNP will need to win over pragmatists, too. In that quest, Scotland's deficit remains a vast obstacle. 

George Eaton is political editor of the New Statesman.