“Rise of the high-flying wives who leave hubby in the home” wrote the Daily Mail. “Tenfold rise in stay-at-home dads in 10 years” was The Guardian’s take.

The Mail’s article, though headlined to suit the paper’s long-term obsession with working women (it isn’t keen) took precisely the same line as The Guardian’s. “The number of stay-at-home fathers has risen tenfold in a decade” wrote a business correspondent.
 
Except that it hasn’t. The actual rise, according to the Labour Force Survey which counts the number of men who give “looking after family/home” as their reason for economic inactivity, was from 5.9 per cent in 2000 to 6.2 per cent in 2010.
 
That’s well short of 900 per cent, by any reckoning. It’s actually about 5 per cent, as Michael Blastland points out in a fierce blog on the BBC College of Journalism web pages. 
 
                
                 Daily Mail, page 24, March 7 2010
 
So what’s going on? Aviva, the insurance company that used to be Norwich Union, issued a press release making the claim, and journalists swallowed it whole, calling up commentators to add their six pennorth of analysis.  
 
How did Aviva arrive at the figures in its press release? For 2000, it looked at the LFS, which records that three million men were economically inactive. Of these, 177,000 (5.9 per cent) gave as their reason that fact that they were looking after the home and family. Aviva misread the tables, selecting instead the number of men who were economically inactive but had been unavailable for work for the past four weeks. There were one million of these men, so that reduced the number to 60,000.
 
Aviva then compared this number with a number derived from a survey it carried out itself of just over 1,000 people. Of these, presumably 500 were men, and 6 per cent said they were “primary carers” (They didn’t say they were unemployed.) Aviva then calculated 6 per cent of 10 million, the number of men with dependent children in the UK. That comes to 600,000 – or ten times the incorrectly extracted figure of 60,000 from the 2000 LFS.
 
I’ve lost count of the number of mistakes here. It’s a shocker, as Michael says. Yet the Press Association and the newspapers mentioned (plus the Daily Express, the Daily Record, and The Sun) all coughed it up unchecked.
 
Haven’t they heard of the internet? It includes loads of ONS data to check this kind of thing, and it’s pretty easy to do. There’s no excuse for propagating myths out of sheer idleness.
 
Aviva, as Norwich Union, used to support a prize for good health journalism, but I'm sure this wasn't quite what it had in mind.