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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Forget gaining £350m a week, Brexit would cost the UK £300m a week

Figures from the government's own Office for Budget Responsibility reveal the negative economic impact Brexit would have. 

Even now, there are some who persist in claiming that Boris Johnson's use of the £350m a week figure was accurate. The UK's gross, as opposed to net EU contribution, is precisely this large, they say. Yet this ignores that Britain's annual rebate (which reduced its overall 2016 contribution to £252m a week) is not "returned" by Brussels but, rather, never leaves Britain to begin with. 

Then there is the £4.1bn that the government received from the EU in public funding, and the £1.5bn allocated directly to British organisations. Fine, the Leavers say, the latter could be better managed by the UK after Brexit (with more for the NHS and less for agriculture).

But this entire discussion ignores that EU withdrawal is set to leave the UK with less, rather than more, to spend. As Carl Emmerson, the deputy director of the Institute for Fiscal Studies, notes in a letter in today's Times: "The bigger picture is that the forecast health of the public finances was downgraded by £15bn per year - or almost £300m per week - as a direct result of the Brexit vote. Not only will we not regain control of £350m weekly as a result of Brexit, we are likely to make a net fiscal loss from it. Those are the numbers and forecasts which the government has adopted. It is perhaps surprising that members of the government are suggesting rather different figures."

The Office for Budget Responsibility forecasts, to which Emmerson refers, are shown below (the £15bn figure appearing in the 2020/21 column).

Some on the right contend that a blitz of tax cuts and deregulation following Brexit would unleash  higher growth. But aside from the deleterious economic and social consequences that could result, there is, as I noted yesterday, no majority in parliament or in the country for this course. 

George Eaton is political editor of the New Statesman.