The harsher grading policies in STEM courses disproportionately affect women; restrictions on grading policies that equalize average grades across classes helps to close the STEM gender gap as well as increasing overall enrollment

Equilibrium Grade Inflation with Implications for Female Interest in STEM Majors. Thomas Ahn, Peter Arcidiacono, Amy Hopson, James R. Thomas. NBER Working Paper No. 26556. December 2019. https://www.nber.org/papers/w26556

Abstract: Substantial earnings differences exist across majors with the majors that pay well also having lower grades and higher workloads. We show that the harsher grading policies in STEM courses disproportionately affect women. To show this, we estimate a model of student demand courses and optimal effort choices of students conditional on the chosen courses. Instructor grading policies are treated as equilibrium objects that in part depend on student demand for courses. Restrictions on grading policies that equalize average grades across classes helps to close the STEM gender gap as well as increasing overall enrollment in STEM classes.


5.3 Grade estimates
The estimated αs, the department-specific ability weights, are given in Table 6. These are calculated by taking the reduced-form θs, undoing the normalization on the γs, and subtracting off the part of the reduced form that θs that reflect the study time (taken from ψ). The departments are sorted such that those with the lowest female estimate are listed first. Note that in all departments the female estimate is negative. This occurs because females study substantially more than males yet receive only slightly higher grades. Given that sorting into universities takes place on both cognitive and non-cognitive skills and that women have a comparative advantage in non-cognitive skills, males at UK have higher cognitive skills than their female counterpart even though in the population cognitive skills are similar between men and women. Negative estimates are also found for Hispanics. While Hispanics have higher grades than African Americans, our estimates of the study costs suggested that they also studied substantially more. Given the very high estimate of Hispanic study time we would have expected Hispanics to perform even better in the classroom than they actually did if their baseline abilities were similar to African Americans. With the estimates of the grading equation, we can reported expected grades for an average student. We do this for freshmen, separately by gender, both unconditionally and conditional on taking courses in that department in the semester we study. Results are presented in Table 7. Three patterns stand out. First, there is positive selection into STEM courses: generally those who take STEM classes are expected to perform better than the average student. This is the not the case for many departments. Indeed, the second pattern is that negative selection is more likely to occur in departments with higher grades. Finally, women are disproportionately represented in departments that give higher grades for the average student. Of the seven departments that give the highest grades for the average student (female or male), all have a larger fraction female than the overall population. In contrast, of the five departments that give the lowest grades (STEM and Economics), females are under-represented relative to the overall population in all but one (Biology).