"...women aren’t getting paid twenty-some percent less than men for doing the same work."

Freakonomics » The True Story of the Gender Pay Gap: A New Freakonomics Radio Podcast: "The big question of the gender pay gap has to be broken down into a set of smaller questions. And then you have to find the data to answer them. When someone like Claudia Goldin does that, it’s pretty obvious that the statistic cited by everyone from Sarah Silverman to President Obama isn’t quite right. Because women aren’t getting paid twenty-some percent less than men for doing the same work. They are, however, often doing different work, or work that affords more flexibility — which tends to pay less. Now, it may be that if you put a dollar value on the flexibility, it could offset a lot of the actual, salary dollars. In any case, there would seem to be kinda-sorta good news here, which is that discrimination doesn’t seem to be the main culprit in the gender pay gap. Or at least it’s hard to find a smoking gun...

It may be a natural impulse, when you hear that women earn less than men, to find someone to blame. One obvious villain is: men, presumably for being discriminatory. But as Claudia Goldin told us, there isn’t much evidence to support the discrimination argument."

See also The ‘Wage Gap’ Myth That Won’t Die - WSJ, The Gender Pay Gap is a Complete Myth - CBS News & The Biggest Myth About the Gender Wage Gap - The Atlantic