Impedance mismatch: are adjuncts better teachers?

I've long argued to my physics colleagues that adjunct professors, selected mainly on the basis of teaching ability, will do as well teaching introductory material as high powered researchers who (often) view their teaching assignment as a burdensome load (as in "teaching load"). It's also true that communication becomes more difficult as the brainpower gap between professor and student increases. (Some wags doubt whether two individuals who differ by, say, > 2 SD in intelligence can really understand each other ...)

Even if you find the results of the paper below unconvincing (perhaps the effect is too small), they nevertheless did not find that adjuncts are worse lecturers than tenure stream faculty. Yes, former and present colleagues, there is an arb to be had here: equal (or better!) quality teaching for students at lower cost, freeing up researchers in the department to produce more scientific knowledge.

The Atlantic: We all know the stereotype about tenured college professors: great researchers, lazy teachers. After all, you don't get tenure by dazzling 18-year-olds with PowerPoints. You do it by convincing other academics you're a genius in your field who's going to bring boatloads of grant money and prestige to campus. And nobody ever won a grant by grading papers.

A gross oversimplification? Of course. But there might also be a hint of truth in the caricature, at least judging by a new study from Northwestern University. The paper--co-authored by university president Morton Schapiro, professor David Figlio, and consultant Kevin Soter of The Greatest Good--finds that faculty who aren't on the tenure-track appear to do a better job than their tenured/tenure-track peers when it comes to teaching freshmen undergraduates.

Previous studies have suggested that colleges tend to hurt their graduation rates by hiring more part-time and non-tenure faculty. But Shapiro and his team wanted to measure the impact of tenure on "genuine student learning," a notoriously tricky task. So how'd they do it? Using the transcripts of Northwestern freshmen from 2001 through 2008, the research team focused on two factors: inspiration and preparation.

To start, the team asked if taking a class from a tenure or tenure-track professor in their first term later made students more likely to pursue additional courses in that field. So, to borrow their example, if an undergrad took economics 101 from an adjunct, and political science 101 from a tenured professor, were they any more likely to sign up for additional poli sci classes. That's the inspiration part. Second, the researchers wanted to know if students who took their first course in a field from a tenure or tenure-track professor got better grades when they pursued more advanced coursework. So, if our hypothetical student took more classes in both economics and poli sci, what did they fare better in? That's the preparation part.

Turns out, tenured and tenure-track professors underperformed on both the inspiration and preparation fronts. Controlling for certain student characteristics, freshmen were actually about 7 percent more likely to take a second course in a given field if their first class was taught by an adjunct or non-tenure professor. They also tended to get higher grades in those future courses. Taking an intro class with a non-tenure track instructor increased a student's mark in their second class by between .06* and .12 grade points, depending on controls. The freshmen who got the biggest boost tended to be less academically qualified students, judged by SAT scores and such, in the hardest subjects.   [Italics mine.]

As the study notes, these patterns held "for all subjects, regardless of grading standards or the qualifications of the students the subjects attracted..." In other words, the non-tenure-track faculty bested their more established colleagues every from English to Engineering.

The paper (NBER):

Are Tenure Track Professors Better Teachers?

This study makes use of detailed student-level data from eight cohorts of first-year students at Northwestern University to investigate the relative effects of tenure track/tenured versus non-tenure line faculty on student learning. We focus on classes taken during a student’s first term at Northwestern, and employ a unique identification strategy in which we control for both student-level fixed effects and next-class-taken fixed effects to measure the degree to which non-tenure line faculty contribute more or less to lasting student learning than do other faculty. We find consistent evidence that students learn relatively more from non-tenure line professors in their introductory courses. These differences are present across a wide variety of subject areas, and are particularly pronounced for Northwestern’s average students and less-qualified students.

This kind of study isn't really using Big Data by scientific standards, but it's an example of "evidence-based" research on higher education that is now made possible by electronic storage of student records and cheap computation. See also Data Mining the University: College GPA Predictions from SAT Scores and Nonlinear Psychometric Thresholds for Physics and Mathematics. The hiding places for "faith-based" theories of education are slowly disappearing -- at least for the numerate. When I discussed the use of adjuncts in past department meetings, I was confidently told by colleagues (who had not looked at any relevant data) that REAL! research physicists did a much better job in the classroom than mere adjuncts. I am dubious of this because many excellent researchers are lousy teachers and either lack the self-awareness to realize it, or just refuse to admit it.