The number is trotted out so often to make a point that it’s become unambiguous: Women in the U.S. earn about 79 cents for every dollar that men do. But recent studies paint a more nuanced picture of the wage gap.

Taking into account several factors, the difference could be just pennies, the studies, from think tanks on different places on the political spectrum, found. Women may make less because they decide to work fewer hours, or because scarce child-care options give them no choice. Some are blocked out of jobs by physical abilities and education. That’s not to say there isn’t discrimination, the studies noted, though it’s responsible for a small part of the chasm.

Where opinions differ is on whether government should work to bring the genders’ aggregate pay in line, or just focus on rooting out illegal inequities.

“There’s no reason that two groups -- that have different educations and choose different occupations and chose different amounts of time at work -- there’s no reason for them to be paid the same,” said Diana Furchtgott-Roth, a senior fellow at the conservative Manhattan Institute for Policy Research. The institute said in a report in April that after controlling for various circumstances, the gap “practically disappears.”

Third Way, a centrist Democratic public-policy group, issued its report in March, saying that while the 79-cents figure is “real,” it doesn’t fully account for the different types of work women tend to do. At the same time, “there remains a gap that cannot be attributed to observable factors,” Third Way said. “That’s the unexplained gap, and it is the strongest evidence of direct gender discrimination within individual workplaces.”

Disproportionate Limits

The fact that much of the divide can be explained doesn’t make it any less urgent an issue to be addressed, said Emily Liner, the author of the Third Way analysis. Government can play a role, she said, because the difference grows as women advance in their careers, probably due to child-care duties that disproportionately limit their options and thus their pay.

The U.S. is the only nation in the developed world that doesn’t mandate maternity leave with pay. Childcare costs for families with two children exceeds that of rent in 500 of 618 metro areas in the country, according to the Economic Policy Institute, a resource group that advocates for workers.

The most effective way to shrink the gap is for companies to make parental leave more generous and equitable regardless of gender, and for the country to figure out how to make childcare more affordable for single mothers, Liner said. “It is going to take years before we can fully address this.”

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