Women make only 80 percent of the salaries their male peers do one year after college or after 10 years in the work force, according to a study quoted by media reports Monday. The study carried out by the American Association of University Women Educational Foundation also found their pay gap widens as 10 years after college, women earn only 69 percent of what men earn.

Even after controlling for hours, occupation, parenthood, and other factors known to affect earnings, the study found that one-quarter of the pay gap remains unexplained, or minly "likely due to sex discrimination."

But, study director Catherine Hill said: "Part of the wage difference is a result of people's choices, another part is employer's assumptions of what people's choices will be. Employers assume that young women are going to leave the work force when they have children, and, therefore, don't promote them."

Women's academic performance was not reflected in their compensation. Women have slightly performed better than men in every major at college, including science and math. But women who attend highly selective colleges earn the same as men who attend minimally selective ones, according to the study.