Conservatives were not at all happy when President Obama issued executive orders to close the gender pay gap earlier this month. And they were particularly angry that Obama justified the change by arguing, famously, “[T]he average full-time working woman earns just 77 cents for every dollar a man earns.”

The figure, according to conservatives, is bunk. And to make their point, they cited an unpredictable source: Claudia Goldin, a highly respected Harvard economist whose research on inequalities facing women in the economy has been widely cited by feminist causes. Here, for example, was Kay Hymowitz, from the right-leaning Manhattan Institute, during an appearance on MSNBC’s “All In with Chris Hayes”:

…we hear all the time, we just heard from the president recently that women only make 77 cents on the dollar. Well, those are raw numbers. Its gross averages that don't take into account hours worked. They don't take into account professions and occupations. And when you take all that into accounted and time offing [sic] for having children, absolutely—then the numbers look very similar. And there's a recent paper that was just released by Claudia Golden at Harvard basically saying, yes, we have achieved a kind of parity.

But while Goldin's research says many things, it doesn't say the wage gap is phony. Just ask Goldin herself.

In her research, Goldin found that the wage gap differs over a woman’s lifetime and increases with age. And the biggest reason is a lack of flexibility when it comes to working hours. “The gender gap in pay would be considerably reduced and might even vanish if firms did not have an incentive to disproportionately reward individuals who worked long hours and who worked particular hours,” Goldin writes. If firms could offer workers more options for how much to work and when to work, she thinks, the wage gap between men and women who work the same hours would nearly disappear.

So what does Goldin think of the 77 cents figure? I asked her. “It’s an accurate statement of what it is,” she said. She compared it to a thermometer: it gives you a reading of the temperature, although it won’t tell you if the weather is going to change or if it’s an abnormal day. In the same way, 77 cents does in fact measure the difference in earnings between all men and women who work full-time, year-round at the median, although it doesn’t reveal all the relevant information—and might obscure some very important details.