Ronald G. Ehrenberg and Liang Zhang, Cornell University
April 2004 |
Our paper analyzes the changing nature of faculty employment in the United States using multiple sources of institutional level longitudinal data. We begin by presenting information, broken down by form of control (public/private) and 1994 Carnegie Category, on how the proportions of full-time faculty that are tenured, on tenure tracks and not on tenure tracks have changed since 1989, using information for a consistent sample of institutions from the annual IPEDS Fall Salary Surveys and the biennial IPEDS Fall Staff Surveys. The latter source also permits us to present similar estimates of the proportions of faculty that are employed part-time.
To analyze the role that economic variables play in causing changes in faculty employment across categories, we conduct two types of econometric analyses. First, we use panel data to estimate demand functions for tenure and tenure track faculty on the one hand and full-time non-tenure track faculty on the other hand to learn how changes in different revenue sources, student enrollment, and the average salaries of different types of full-time faculty influence the distribution across categories of full-time faculty. We also estimate equations designed to explain the role that revenue and enrollment changes play in influencing the relative employment of part-time and full-time faculty.
The above analyses are equilibrium in nature and assume that actual employment of different categories of faculty can always quickly adjust quickly to desired equilibrium employment levels. Our second set of econometric analyses relaxes this assumption in two ways. First, we estimate lagged adjustment models in which the lags depend upon the initial share of an institution’s faculty members that are tenured. Second, we estimate models in which we seek to explain the flows of new hires of each type of faculty member (rather than the levels of faculty employment) using data on new hires that are available in the IPEDS Fall Staff Surveys.
To explain new hires, one needs variables that reflect changes in demand, such as enrollment and revenue changes, as well as variables that reflect the number of potential vacant positions to be filled. We construct information on the latter using data that the American Association of University Professors (AAUP) collects (put does not publish) each year as part of its annual salary survey on the number of continuing faculty members in each rank. The AAUP defines continuing faculty members in a rank as faculty members in a rank on a universities payroll one year, who are also on the payroll the next year, regardless of their rank in the second year. Summing up an institution's continuing faculty members across ranks in the second year and subtracting the total from the institution’s total faculty employment in the first year provides us with an estimate of the number of faculty vacancies that the institution could have filled in the second year if it had replaced all departing faculty.