At the end of the semester, students who enjoyed the course should just tip their professors. Adding a real free-market incentive would increase class size and

At the end of the semester, students who enjoyed the course should just tip their professors. Adding a real free-market incentive would increase class size and teaching quality, right? Let's let the invisible hand of the market decide He said sarcastically. Ah well, I guess that's a lesson learned re: snark and downvotes. There's a lot to say about the 'signaling' point made upthread, and I agree with that. Anyway, the important issue here is that course evaluations can serve two purposes. One purpose is the structural elimination of "bad" instructors, by linking promotion and retention decisions to course evaluations at the departmental and/or university level. I can tell you from my perspective, course evaluations have never realistically served this purpose at the two institutions where I taught. The other purpose is to provide concrete feedback to the instructor so that they can improve their teaching the next semester. Official course evaluations are rarely useful for this purpose either, and in my experience ask the wrong questions (and at the wrong time - wouldn't it be better to get feedback from your students after three weeks so you can make course corrections?) So good professors tend to supplement official feedback forms with feedback instruments of their own design.