Gender Differences in Salary at UMN-TC, 2007:
A Comparison of the Women’s Faculty Cabinet and Clayton Studies
Prepared by the Women’s Faculty Cabinet and associates, August, 2011
Goal. The goal of this document is to provide a summary of the differences between the approaches taken in the two salary studies carried out by the Women’s Faculty Cabinet (WFC) and by Dr. Murray Clayton to assist readers in interpreting and using these studies.
History. Early in 2010 the WFC completed a report describing their study of gender differences in faculty salaries at the University of Minnesota Twin Cities (TC) campus using 2007 data.[1] This study found that that, even after adjusting for 16-18 variables including indicators for discipline, experience and rank, male faculty earned on average more than female faculty, particularly at the rank of full professor (see Figure 1). The WFC presented its findings to the Provost during the summer of 2010.
Figure 1: WFC analysis of salary by rank.
The Provost felt that these findings demonstrated an issue requiring further investigation and provided funds for an outside consultant to conduct a second salary study. Carol Carrier, VP of Human Resources, appointed a search committee that selected Dr. Murray Clayton from the University of Wisconsin. Clayton holds joint appointments in the departments of Plant Pathology and Statistics. Clayton commenced work on his study in Spring of 2011 and completed his report in early Summer 2011 (see Figure 2).[2]
Similarities in approach. Both used the 2007 salary data for the University of Minnesota Twin Cities campus (excepting the Academic Health Center). Both used multiple linear regression approaches, and worked with the Office of Institutional Research who did the actual analyses. Both explored multiple models, and adjusted for factors such as experience, discipline and rank. Neither included merit; both assumed that men and women are equally meritorious.
Differences in approach. The most important difference was that the Clayton study included many more variables related to discipline in the analyses. The major differences are summarized by:
· Discipline variables: Clayton’s analysis included almost 100 variables to account for discipline, including average salaries for a given field at peer institutions. The WFC analysis used 9 discipline variables.
· Method: Clayton used a natural log transformation of the salary data to reduce the impact of heteroscedasticity.
· Analyses by college. In addition to analyses at the University level with rank (1.8%), without rank (2.5%), and averages of the two (2.2%), Clayton reported analyses at the college level with rank, without rank, and averaged.
· Numeric gap representation. Clayton used positive salary gaps to indicate higher salaries for women, while the WFC used positive gaps indicate higher salaries for men. This report uses the convention of the WFC report.
Figure 2: Clayton analysis of salary by rank.
Similarities in findings. Although the specific findings of the WFC and Clayton studies differed, both found that:
· There are unexplained gender differences in salary,
· Salary gaps are not evenly distributed across ranks; gaps are most substantial at the rank of full professor.
Differences in findings. Clayton’s study found smaller differences averaged across the university and all ranks, and at each rank than did the WFC study (see Figures 1 and 2), primarily because of the inclusion of more variables related to disciplinary differences in salary in Clayton’s study. Additionally, Clayton’s college-level analyses suggest that:
· Salary gaps are not evenly distributed across colleges Some favor men, and some favor women. Gaps averaged across all ranks at the college level ranged from negligible (-0.5%) to substantial (7.3%) (See the “combined” column in the table on page 5 of Clayton’s report.)
Summary. Unexplained differences between male and female salaries still exist at the University of Minnesota TC campus. Those differences may be larger or smaller than the campus-wide averages within individual colleges and at specific ranks, particularly the rank of full professor. To attract and retain our best faculty, we must insure that both female and male faculty members receive salaries commensurate with their accomplishments and market value.
[1] The WFC’s report & highlights can be found at: http://www.academic.umn.edu/wfc/reports.html
[2] Murray K. Clayton, 2011, A Statistical Investigation of Gender Equity in Salaries of Faculty at the University of Minnesota.