A 1-standard-deviation increase in university teachers’ effectiveness in boosting student performance reduces the students’ evaluations of their professors’ teaching quality by about half of a standard deviation, on average — enough to significantly reduce the teachers’ percentile ranking at the university, says a team led by Michela Braga of Bocconi University in Italy. Students, especially the least able, appear to respond negatively in their evaluations to the extra effort that good teachers require of them, a finding that casts doubt on universities’ reliance on student evaluations to inform faculty-promotion decisions. The researchers also found that student evaluations improve when there is fog and as the weather gets warmer, and they deteriorate on rainy days.

Source: Evaluating students’ evaluations of professors