Colleges and universities of all kinds are increasingly relying on non-tenure-track faculty members. And administrators frequently defend their hiring choices by citing money. Since adjuncts are paid less than those on the tenure track (and frequently lack benefits), it costs colleges less to have a section taught by an adjunct than by someone who is tenured or on the tenure track.

But where do the savings go?

The American Institutes of Research released two studies Wednesday to answer that question. Both studies use data from the Delta Cost Project -- which is highly regarded for tracking how colleges spend money -- and both were sponsored by the TIAA Institute.

With regard to savings, the studies suggest that what colleges are saving on instructional costs isn’t resulting in more investment in tenure-track faculty, as some might hope. Rather, the savings appear to be showing up elsewhere, if at all.

Here are some of the key findings:

• Private four-year colleges that use large proportions of non-tenure-track faculty members spend 37 percent less on full-time faculty members of all kinds than do similar institutions with small shares of non-tenure-track faculty members. But looking at spending on all categories of full-time employees, these institutions are spending only 19 percent less than those with small shares of non-tenure-track faculty members. So more spending seems possible on the administrative side of the house.
• The same is true for public four-year colleges, although the spending gaps are 24 percent and 14 percent, respectively.
• Public four-year colleges are using the savings in instructional costs from relying on adjuncts to increase spending on other areas -- namely maintenance, administrative and student-services staff. Most of this spending is in recruiting, admissions, counseling, student organizations and athletics.
• Community colleges and private four-year colleges also reduced instructional costs, but they didn’t add to expenses elsewhere, so costs do not actually shift due to increasing reliance on adjuncts.

The above findings come from one of the reports, "The Relationship Between Part-Time and Contingent Faculty and Insti...."

The other report -- "The Shifting Academic Workforce: Where Are the Contingent Faculty?" -- provides data on the pervasive use of adjuncts.

Notably, the gains are significant throughout higher education. Community colleges saw relatively small increases in adjunct reliance during the 10 years studied, but that's because their use was already greater than in other sectors.

Between 2003 and 2013, the study finds, the share of faculty members who were off the tenure track increased from:

• 45 to 62 percent at public bachelor’s degree-granting institutions.
• 52 to 60 percent at private bachelor’s-granting colleges.
• 44 to 50 percent at public research universities.
• 80 to 83 percent at community colleges.

So what do these findings mean? Advocates for faculty members and adjuncts in particular said the findings vindicated points they have been making for some time.

Maria Maisto, president of the New Faculty Majority, which works on behalf of those off the tenure track, said via email that "the reports really show that the shift to a contingent academic work force was motivated by economic (and, I would argue, political) concerns -- disempowering the faculty by making them economically precarious of course reduces their influence and weakens shared governance, giving administrators more power."

She added that "the reports show what we have known -- that the shift to contingent faculty was not guided by research on quality of education and what actually works to enhance and support student learning. Economic concerns have always been primary, whether deliberate or in response to some imposed austerity."

John Barnshaw, director of research and public policy at the American Association of University Professors, said that he thought one of the most significant findings was that savings on instructional spending were being used at public four-year colleges to increase administrative spending.

"The AAUP has noted this for years," he said, even as many administrators have suggested otherwise. "It is nice to have longitudinal data to independently validate these prior claims."

Steven Hurlburt, an AIR senior researcher and co-author of the report, said via email that he viewed the reports as suggesting that colleges should consider carefully the impact of relying on non-tenure-track faculty members. He noted that the emphasis of this study was on costs and not on educational quality, a crucial issue for colleges. But he noted that not everyone is saving as much money as some would expect.

"I would suggest that colleges should perhaps exercise caution," Hurlburt said. "Relying more heavily on contingent faculty may not be the institutional cost-saving panacea many colleges and universities may think …. While we found that colleges and universities with larger shares of contingent faculty had lower faculty costs, we did not see the same level of savings when looking at total compensation costs for all employees, due, in large part, to nonfaculty costs, particularly those related to benefits."