“Surveys that include CEOs of smaller companies, both publicly and private held, show women making strides in pay, though a gap persists. Female CEOs earned nearly 80% of their male counterparts’ compensation in 2013, according to a study from the Institute for Women’s Policy Research based on Labor Department data. Two years ago, women who were CEOs earned 69% of what men who were CEOs were paid.

“It definitely looks like progress,” said Heidi Hartmann, president of the think tank. “Something that’s really changed in the last few years is the scrutiny.”

Wage gaps could stem from women’s shorter tenures at the top, their tendency to lead smaller companies or gender discrimination, economists and sociologists said.”