"... are correlated with students’ expected grades. Studies have found that, among other things, students score male professors higher than female ones, rate attractive teachers more highly, and reward instructors who bring in cookies. 'It’s not clear what the evaluations are measuring, but in some sense they’re a better instrument for measuring gender or grade expectations than they are for measuring the instructor’s actual value added,' Philip Stark, a UC Berkeley statistics professor who has studied the efficacy of teacher evaluations, told me.
From
"How Teacher Evaluations Broke the University/'We give them all A’s, and they give us all fives'" (The Atlantic)(gift link).
From the last paragraph: "There’s another reason to keep them around. If universities ever did away with students’ ability to grade their professors, college kids—and their tuition-paying parents—might revolt." Isn't that how student evaluations came about in the first place? The students were revolting.