Great new paper in the latest issue of the American Economic Journal: Applied Economics about the political orientation of your professor and the grade you may receive in her/his class:
We study grading outcomes associated with professors in an elite university in the United States who were identified—using voter registration records from the county where the university is located—as either Republicans or Democrats. The evidence suggests that student grades are linked to the political orientation of professors. Relative to their Democratic colleagues, Republican professors are associated with a less egalitarian distribution of grades and with lower grades awarded to black students relative to whites.
The paper is by Bar and Zussman and their models look at variations in grades within the same student taking courses in the same department, so it controls for selection into majors and, to some extent, classes. The most interesting part of this paper is the race angle. One may think that it has something to do with the fact the demographics of Republican professors, not so much their ideological preferences. Not so: even controlling for gender, age and race of the professor doesn't change the results.
So how to interpret this? I'm sure that many would argue that Republican professors harbor some subtle, perhaps subconscious, prejudices against black students (this guy would agree). This is entirely possible, but I think the study needs to be interpreted with some caution. First, the sample size of Republican professors is small (only 5.3% are). Secondly, its unclear where the grade variation is coming from. Do students - black or white - perform worse in Republican-professor taught classes (they don't like the take on the material, they may be too ticked off with partisan politics to focus on assignments, etc)? The study can't distinguish this explanation from the racist-professor one.