Faculty salary divides between different disciplines and between different universities

An article today at Inside Higher Ed discusses a soon-to-be-published study from the Cornell Higher Education Research Institute on faculty salary divides both across different disciplines (especially engineering and humanities) and across different universities:

Why do aerospace engineering professors make a little more money than classics professors at some public universities, and a whole lot more at others? [...]

The researchers looked at 1992-3 salary data from 88 institutions, 85 of which are public, many of them flagships or other research insitutions. The researchers already knew that computer science teachers at a given institution make more than philosophy instructors, but what they found was that the relative spreads between any two particular disciplines were widely variable at different universities. The study found a correlation between department quality as determined by National Research Council ratings, and the relative pay of faculty members in different disciplines.

For example, if a college%u2019s economics department was rated well and its English department only average, the salary gap between economics and English faculty members at that institution was likely to be larger than the gap at an institution where both were rated equally.

The article also cites the research director of the American Association of University Professors who is worried by this trend:

Higher education really is something for the common good that provides a benefit for society as whole. When you see some of these large differences, it’s easy to slip into a system that emphasizes individual payback instead of payback for society. [...]

As public support declines, institutions become more driven by the outside market. [...] If we move to a more corporate structure, then there’s an idea of ownership of data or information, and of limited exchange, and that, in the long run, will damage the whole enterprise.

But there's another potential that the article doesn't report, but which the original Cornell study suggests: the divide between faculty at the same university, in the same discipline, but of different genders. From the original working paper:

One hypothesis that we did not address in the paper is whether differences in field differentials in full professor average salaries across universities also may reflect differences in the gender composition of faculty in different departments at different universities. To see why this might occur, consider the following example: Suppose there are only two universities and two departments, economics and English at each. Suppose the economics department at each university hires only males and economists receive the same average salaries at both universities. Suppose further that the English department at the first university hires only males and that the English department at the second university hires both males and females and that the male faculty at both English departments receive the same average salaries, which are lower than the average salaries paid to economics faculty. Finally, suppose the English department at the second university pays its female faculty members a lower average salary than it pays its male faculty members because of gender discrimination or other factors.14 If this situation prevailed, the ratio of the average salary of economists to the average salary of English professors would be higher at the second university.

Put simply, if, as a long literature suggests, female faculty members on average get paid less than male faculty members, other factors held constant, differences in the gender composition of faculty members within a field across universities may influence the average salary of faculty members in the field vis-à-vis their colleagues in other fields at an university.

(Cite: http://www.ilr.cornell.edu/cheri/wp/cheri_wp60.pdf)

What I think this report should remind us of is that there's a discussion that needs to happen about the value of information labor in higher education, connecting all of these disparate divides (and other potential divides according to prestige of the university, money available for research expenses, ability to hire high-quality graduate students, cost-of-living differences of the local university community, and the like) in order to allow academics to speak with a greater collective voice, not only about their own bread-and-butter worklife issues, but about the place of academia in society as a whole.