Shock study: Professors not seeking tenure make better teachers

File this under "entirely unsurprising, but still noteworthy," via Inside Higher Ed:

A major new study has found that new students at Northwestern University learn more when their instructors are adjuncts than when they are tenure-track professors. ... [T]hey note that previous studies have looked at the impact of adjunct instructors on graduation rates and retention rates. But they argue that it is important to shift the analysis to student learning and to behavior associated with student learning. ...

The study tracked eight cohorts of freshmen (those who entered from fall 2001 through fall 2008), and looked not at the grades or completion in the courses taught by the adjuncts, but at whether students enrolled in another course in that subject and the grades that students earned in that course. The study found that students were significantly more likely to enroll in a second course in the subject when the first course had been taught by an adjunct, and that they were likely to earn a higher grade in that second course if the first had been taught by an adjunct.