The median salary for women working full-time is about 80 percent of men's. That gap, put in other terms, means women are working for free 10 weeks a year.

So, if you're a woman ...

.. you started working for free on October 26.

Well, that is a little blunt — there are gradients on that difference. The pay gap varies depending on the occupation, working hours, education attainment, experience, and geography.

That explains part of the difference in pay between men and women, but not all of it. And even though most economists agree that after adjusting for age, education, experience and other variables there's still an unexplained gap, there are voices who argue that the gender pay gap is a myth.

Pay gap deniers purport that women's choices, rather than discrimination, cause the pay gap between women and men. But those choices are actually consequences of the social forces at play.

Also, women of color get hit twice: they suffer the effects of the gender wage gap plus those of the race wage gap. While wages for White and Asian women have improved since 2007, salaries for Hispanic women have flatlined, and even declined for African American women.

CLAIM

Women choose lower-paying jobs

Sort of. Women do tend to hold occupations that pay less.

Industry and occupational sorting into 'female' and 'male' jobs accounts for the largest portion of the 'explainable' part of the gap. In 2016, the job search engine Glassdoor did an analysis using half a million self-reported salaries and found that, for their data, occupational sorting accounted for about half of the pay gap. Other studies say it explains about a third.

But some jobs became lower-paying for everyone when women started doing them.

A comprehensive 2009 study by Paula England of New York University, Asaf Levanon of the University of Haifa in Israel and Paul Allison of the University of Pennsylvania used census data from 1950 to 2000 to confront two views used to explain the observed decrease in median earnings as women entered a field: queuing and devaluation.

The first view, known as queuing, says that as the pay for a profession drops, the job becomes less attractive. People turn to other, higher-paying occupations, but because employers —the view assumes— generally prefer men, it's them who fill those jobs, so women remain in lower-paying ones.

The second view, devaluation, shifts the cause and effect. It says that the perceived worth of a job depends on which of the two sexes holds it, that society views professions occupied mostly by women as of less value —and so do employers; hence when women start filling a job, its value decreases. The study suggests that it is devaluation that explains the drop in pay as more women enter a profession.

Devaluation also explains how two very similar occupations, janitors (mostly men) and housekeepers (mostly women), have different pay scales. The woman-dominated job, housekeeping, has lower pay than janitorial work. Janitors make $12.91 an hour for men, $10.25 for women; housekeepers $11.27 and $9.84, respectively.

Here's how much median earnings for each job changed, for men and women , from 1960 2015:

CLAIM

Women choose to work part-time

You keep saying 'choose'. So let's talk about 'choice'.

Yes, a larger share of women than men work part-time, fewer than 35 hours a week, and more women take career breaks or reduce working hours for family reasons.

But the U.S. is an anomaly among developed countries, with no federally mandated parental paid leave. In Canada, mothers have 17 weeks, paid at half rate; in Spain and the Netherlands 16 weeks, in Germany 14, in Mexico 12, all fully paid; and 39 in the United Kingdom, although paid at a 30 percent rate on average, so the equivalent to 12 weeks.

And in a 2013 survey by the Pew Research Center, more than half of the respondents thought children were better off if the mother stayed home, 34 percent believed they'd be as well off if she worked. Only 8 percent said they'd be better off if the father stayed home.

So parental leave policies, social norms, and family math —married women still make less than their husbands— influence personal decisions about how much to work. That's why the word 'choice' is so charged.

Also, working more hours doesn't mean earning more money.

Although women who work part time fare slightly better than their male counterparts, they represent just a fraction of all working women. More than two thirds work 35 hours or more per week and still fall short.

CLAIM

It's not the case for younger, more educated women

Women are just now more likely than men to have a bachelor's degree, so the education level did explain part of the pay gap for older women, but not that much —the Glassdoor study stated that education and experience account for less than 15 percent of the 'explainable' gap.

So while it's true that the gap is wider for women older than 35, it is not altogether gone for women who are younger and more educated.

What this all hints to is that the causes of the gender gap are many and more nuanced than just individual choices or corporate discrimination. However you slice the data, the gap is there. Only by recognizing the complexity of the variables that play into the gap can companies and the government enact policies to root out the deeper causes of those disparities, instead of alleviating its symptoms.