Higher education has helped women narrow the wage gap but there is one college-related factor that has becoming increasingly important in perpetuating that gap, according to new research.

And that factor is their college major.   Women dominate the social sciences, for example, so by not moving more into hard sciences, the numbers are not normalizing across all fields.   Women at the higher levels of research and in disciplines like engineering show no modern wage gap.

Donna Bobbitt-Zeher, author of the study and assistant professor of sociology at Ohio State University at Marion used data from the National Longitudinal Study of the High School Class of 1972 and the National Education Longitudinal Study of 1988. With these data sets, she was able to compare women who graduated from high school in 1972 and 1992. She compared the incomes of college graduates seven years after their high school graduations, in 1979 and 1999. Both samples included about 10,000 cases.

Findings showed the income gap between college-educated men and women declined significantly in 20 years – in 1979, women’s earnings were 78 percent of their male counterparts, but by 1999 the women were earning 83 percent as much as men.

Bobbitt-Zeher then estimated how much of that income difference between men and women was explained by various factors in 1979 versus 1999. Some of the factors she examined included occupations and industries that men and women work in; background, including socioeconomic status and race; how much individuals valued earning a lot of money; factors related to parental and martial status; SAT scores; the colleges that people attended and whether they earned graduate degrees; and, of course, the percentage of women in their college majors.

Findings showed that about 19 percent of the income gap between college-educated men and women in 1999 could be explained by their college major,  nearly twice as much as in 1979, when 10 percent of the gap was explained by college major.  Although work-related characteristics combine to explain a bigger share of the gap, no other single known factor was more important than college major in explaining the income gap in 1999.

Many college majors did become more integrated between 1979 and 1999, she noted.

“Most of integration has come from women making different choices, rather than men moving into traditionally female fields,” Bobbitt-Zeher said.

However, significant differences remain in the majors women and men choose. And this is contributing to the gender income gap in a more meaningful way than it did in the past.

But the continuing wage gap isn’t explained completely by men choosing majors that require greater skills than majors chosen by women, she said, and the reasons for the gender segregation of majors are not entirely understood, she said, since much of it is a matter of personal choice.

Bobbitt-Zeher said the results should be a reminder for us not to believe gender inequality in higher education is a problem of the past.

“There’s been a lot of attention paid to the fact that women seem to be doing so well in college compared to men. But what people don’t know is that education is playing a bigger role than ever in perpetuating the gender income gap,” she said.  “It’s an issue that we need to keep at the forefront.”

No mention of outreach for men in education and psychology fields, though, where the ratio in favor of women is the same as men in particle physics.

Bobbitt-Zeher presented her research August 9 in San Francisco at the annual meeting of the American Sociological Association.