Broadly, it shows that full-time, relatively stable and (presumably) well-compensated non-tenure-track faculty do well in the classroom.But professors of the practice (I believe that's the Duke term) and senior lecturers, whether on long-term contracts or not, do not sit on curriculum committees or on the University Council. Perhaps administrators like it that way.
Specifically, the paper outlines evidence for two conclusions: 1) that students "learn" better during their first term at Northwestern in classes led by non-tenure-track faculty, and 2) that students taking classes with non-tenure-track faculty are more likely to take another course in the same discipline.
At the end of a report on a study contrasting non-tenure-track to tenured and tenure-track faculty, we are told that hiring "teaching-intensive lecturers" in addition to "research intensive tenure-track faculty" is an "efficient" solution to the problems facing administrators at research institutions.Indeed.
Notice how the operative distinction has shifted to one between teaching and research-intensive faculty — but without quite disconnecting it from the issue of tenure.
Given this shift, the claim may be true. But there is nothing about teaching-intensive faculty that is incompatible with their being eligible for tenure — especially if one fully intends to build long-term relationships with them and keep them around.
Why, one is led to ask, can we not have "efficiency" and tenure? The answer, if there is one, must have to do with other ways in which non-tenured faculty differ from those with tenure. The authors mention academic freedom — an important consideration.
But they otherwise ignore the degree to which non-tenured faculty lack a secure position from which to question, criticize, or oppose the actions of university administrators.
And here, indeed, is another sense of "efficiency" that administrators at many institutions might well wish to cultivate, allowing them to enjoy a pedagogically effective, but largely vulnerable, and therefore easily controlled faculty.