July 13, 2000
In the past few months, several researchers have issued studies on wage disparities between men and women professors. The identified gap ranges from 6.2-8 percent. All three analyses use data from the National Survey of Postsecondary Faculty (1993), conducted by NCES. The subsamples used for the analyses differ somewhat, as do the regression models (variables included, as well as their construction). This no doubt accounts for differences in the estimated gender gap in salaries. Below are brief summaries of these studies.
Nettles, Michael, Laura W. Perna, Ellen M. Bradburn, and Linda Zimbler. 2000. Salary, Promotion, and Tenure Status of Minority and Women Faculty in U.S. Colleges and Universities. Washington, DC: U.S. Department of Education (NCES 2000-173).
The sample is restricted to full-time faculty at two- and four-year institutions whose primary responsibility is teaching (representing 59 percent of the total NSOPF-93 sample). The regression analysis shows that women earn 8 percent less than comparable men (Table 26, Model 4). The regression controls for race, years since highest degree (in ten-year categories), holding a doctorate or professional degree (versus another degree), level of instruction (undergraduate, graduate, or both), ratio of percent time spent in teaching to time spent in research, number of publications in the two years prior to the survey, institutional type, region of the country where institution is located, Biglan categories (three variables: life systems versus non-life systems field; hard versus soft field; and pure versus applied field); tenured (versus not tenured); and rank.
Perna, Laura Walter. 2000. Sex Differences in Faculty Salaries: A Cohort Analysis. Paper presented at the annual meeting of the American Educational Research Association, New Orleans.
The sample includes only full-time regular faculty (more restrictive than Nettles et al., which seems to include non-regular faculty). Perna finds a 7 percent wage gap after controlling for a more extensive array of variables than Nettles et al. (e.g., Perna includes whether married and whether have dependents; whether a department chair; whether unionized; time spent on service and administrative activities).
Perna then divides the sample into synthetic cohorts: assistant professors with 1-2 years of experience; assistant professors with 3-6 years of experience; associate professors with 7-12 years of service; associate professors with 13-20 years of service; full professors with 13-20 years of service; and full professors with more than 20 years of service. She uses the same regression model as used for her total sample for each cohort (Table 4). She finds no statistically significant wage gap for assistant professors with 1-2 years of service, associate professors with 7-12 years of service, and full professors with 13-20 years of service She does find a nearly 7 percent difference for assistant professors with 3-6 years experience, an 8 percent difference for associate professors with 13-20 years of service; and a 4 percent difference for full professors with more than 20 years of service. Perna suggests that the lack of a wage gap for more recently hired and promoted faculty is because institutions equalize male and female salaries when faculty members are promoted.
Toutkoushian, Robert K. 1998. Sex Matters Less for Younger Faculty: Evidence of Disaggregate Pay Disparities from the 1988 and 1993 NCES Surveys. Economics of Education Review 17 (1):55-71.
Toutkoushian's sample is the most restrictive of the three studies, including only full-time faculty at four-year institutions who hold the rank of assistant professor or higher. Analyses compare previous studies and wage gaps; gaps by field, type of institution, etc. Using a comprehensive regression model (though slightly fewer variables than Perna), Toutkoushian finds a wage gap of 6.2 percent for the NSOPF-93 data (Table 2, model 2). Using a model comparable to that of earlier studies, he finds a gap of 7.5 percent (Table 3, 1993 column).
Toutkoushian also compares the wage gap for faculty in different age groups using two NCES faculty surveys (1988 and 1993). He finds that for both surveys the wage gap is smaller for younger women (40 and younger) than for more senior women, and that the gap is smaller for younger women in the 1993 survey than for younger women in the 1988 survey. He did not find a significant widening of the gap for women who were between the ages of 30 and 40 in 1988 and women who were between 35 and 45 in 1993. He also did not find appreciable differences across surveys when comparing the wage gap for women in older age groups. Toutkoushian interprets these findings as possible evidence that discrimination faced by younger women lessened between the time of the two surveys. He suggests that as older women retire, the persistent wage gap evident in national surveys may begin to decline.