Where is David Cameron getting his information from?

It's distinctly uncomfortable to find the country being run by someone who is not well informed. Worrying even. And David Cameron does seem to be remarkably ill informed on the subject of the gender pay gap:

“Today I’m announcing a really big move: we will make every single company with 250 employees or more publish the gap between average female earnings and average male earnings. "That will cast sunlight on the discrepancies and create the pressure we need for change, driving women’s wages up."

For, as we've explained many a time here we don't really have a gender pay gap. There's a motherhood pay gap, most certainly. And men and women do tend to cluster into specific professions and jobs: pay not being equal between all jobs of course. And that's about it. Once anyone takes a close look we can't find any difference at all (perhaps, maybe, a one or three percentage point residual) between wages of men and women simply on the grounds of their being men and women. The rest of the difference is explained by job choices, hours worked, qualifications, education and so on.

We can even show that it's a motherhood pay gap, not a gender one. For there's a point at which women go from earning more than men to earning less. And that point, that age of life, has been advancing pretty much in lock step over the decades with the average age of primagravidae. And let us be honest about this. In a viviparous mammalian species we're really just not that surprised that there's some gender differentiation in the care and raising of the next generation, are we?

And there's something more worrying too:

However, women on average still earn 19.1 per cent less than men - equivalent to 80p for every pound earned by a man.

That is using mean wages and not median. And Harriet Harman was rapped over the knuckles by the Statistics Commissioner for doing that. Medians are what we should be using here, that use of the mean is grossly misleading.

And, well, you know, surely we can expect a Prime Minister to better than Harriet can't we?