Recalling my post in July on "the profits of pulchritude", a local couple who are both professors sent me a link to a paper on the relationship between student learning and student evaluations. Most faculty know that if you are going to be evaluated for retention, promotion and tenure on the basis of student evaluations, you can juice your evaluations by giving easier grades. The literature in this area point to five possible explanations: (1) better teachers get better evaluations and increase student learning, leading to higher grades; (2) better, more motivated students give higher evaluations and get higher grades; (3) course-specific motivation affects both grades and ratings; (4) students learn the quality of the course and their own ability from received grades (I'd call this the Lake Woebegone effect); (5) high ratings are in effect a tip left behind for providing easy grades. Most of the evidence out there, alas, seems to point towards (5).

There is also some evidence that there are halo effects -- "my instructor can do no wrong" -- that might be correlated with physical attractiveness. It is possible that they interact.

So, what do they find? using data from RateMyProfessor.com,

...students rate professors in the Accounting, Engineering, Computer Science, and Math departments lowest for quality, and they consider courses in these departments to be among the most difficult. Students also consider many of the professors teaching these courses to be the least sexy on campus. At the other end of the spectrum, students rate professors of Law, Languages, and Education as being the highest quality on campus. They are also among the easiest and sexiest.

Up to 51% of the variation in student evaluations are explained by perceived easiness and "hotness". This is a problem then -- could I increase my sexiness simply by being easier (which is more possible than my losing 40 pounds)?

For sexy professors, the correlation between Quality and Easiness is lower than for their non-sexy colleagues, and the mean scores for Average Quality and Average Easiness are higher as
well.

If you are "hot" (which commenters on RateMyProfessor say doesn't necessarily mean sexiness), you don't get as big a bang for the buck from grade inflation as you would if you're not hot.

The authors caution using student evaluations for promotion and tenure decisions, but my view is that you've thrown away good information. As the study shows, if you take professors who have high quality ratings and low easiness ratings you find evidence from student comments that there's some real learning going on. Being tough and getting low evaluations isn't necessarily any more laudable a goal than being easy and getting high ones. More measurement, and more thoughtful use of measurement, is what we desire.