Sen. Patty Murray (D-Wash.) (C) speaks about the Paycheck Fairness Act during a news conference with Sen. Barbara Boxer (D-Calif.), Sen. Dianne Feinsten (D-Calif.), Sen. Debbie Stabenow (D-Mich.) and Sen. Barbara Mikulski (D-Md.) in the Lyndon B. Johnston Room at the U.S. Capitol May 23, 2012 in Washington, D.C. The Democratic bill to close the pay gap between men and women fell short today in the Senate along clear partisan lines. - 

Kai Ryssdal: The Paycheck Fairness Act got stuck in the Senate today, as expected. It would have helped close the pay gap between men and women.

That was the argument from the White House and Senate Democrats, anyway. Republicans say it was just election-year legislating, gender politics at its most financial.

The White House claims women make 77 cents for every dollar a man does. The other day, the St. Louis Fed figured it's more like 95 cents. We've also seen 82 cents bandied about as the gender pay gap.

Marketplace's Sarah Gardner did a little apples-to-apples comparison.

Sarah Gardner: Seventy-seven, 95, 82? Will the real gender pay gap please stand up?

Ariane Hegewisch at the Institute for Women’s Policy Research says she’s even seen an older study that put women’s pay at 38 cents to a man’s dollar. How’d they come up with that depressing number?

Ariane Hegewisch: It’s a longer-term earnings figure over 15 years of time.

Which includes, of course, women’s time out of the workforce to have kids. So, where did Obama get his gender gap figure?

Hegewisch: The 77-cent figure is based on the annual earnings of everybody who works full-time and has earnings for at least 50 weeks a year.

Which doesn’t count lots of women who work full-time hours, but not all year long. If you do that, the wage gap narrows to 82 cents on the dollar. When you factor in for years of experience, career choice and so forth, it gets closer to that 95 percent figure the St. Louis Fed favors. So it’s easy to cherry pick the numbers here, depending on your politics.

Christina Hoff Summers at the conservative American Enterprise Institute says Obama’s numbers don’t reflect discrimination, just men and women’s choices.

Christina Hoff Summers: What they study in college, professions they enter, number of hours they work per week. It’s different for men and women.

But Ariane Hegewisch says that’s why she thinks Obama’s 77-cent figure is fair. It reflects the fact that even in 2012, occupations dominated by women very often pay less.

I’m Sarah Gardner for Marketplace.

Follow Sarah Gardner at @RadioGardner