On grade distribution, Republicans were more likely to give very high and very low grades. Among grades given by Republicans, 6.2 percent were C- or lower, compared to only 4.0 percent of the Democratic grades. But Republicans were also more likely to give out A+ grades (8 percent of their grades, compared to only 3.5 percent from Democrats).
With regard to race of students, the study found that black students received lower grades, on average, than did white students whether classes were taught by Democrats or Republicans. In courses with Democratic professors, the gap was 0.27 on a grade point average. In Republican-led classrooms, the gap was 0.42.