The soon-to-be-completed leadership succession at Xerox from Ann Mulcahy—a woman—to Ursula Burns—also a woman—is one for the record books. It will be the first woman-to-woman transition at a Fortune 500 company, and Burns is the first African-American woman to take the helm of any such corporation.
Mulcahy has balked at the notion that the über-competent Burns needed her help—or anyone else's—in making her way through the ranks. Nonetheless, the paucity of women in senior positions who might in turn mentor young women on their way up the ladder is one of the primary reasons put forth to explain the continued existence of the glass ceiling in corporate America. In science and technology, the situation is even bleaker—women are under-represented at every level, from advanced college classes to the executive suite, making Burns' rise from math major to CEO of tech giant Xerox all the more remarkable.
Of course, female mentorship is only one strand of a complex web of explanations—from aptitude to temperament to societal discrimination—for the gender gap in science and elsewhere. A recent National Bureau of Economic Research Working Paper on gender and academic achievement at the U.S. Air Force Academy, however, finds that the importance of female mentors may be even more powerful than previously thought. The study, by University of California-Davis economists Scott Carrell and Marianne Page and their colleague James West at the Air Force Academy, finds that replacing a male instructor with a female one has such a strong effect on female achievement as to erase the gender gap entirely.
The trio of economists examined the undergraduate careers of 9,481 cadets taught by nearly 250 different science and math instructors at the USAFA during the years 2000-08. Untangling the impact of an instructor's gender from the many other factors that influence student performance has hamstrung most research on the topic: If women taught by women perform better (or worse) is it because the instructors attract better (or worse) female students rather than teach them better? Or is it because women "dumb down" their syllabi or exams to make it easier for lower-performing women to do well? Or is it something else entirely?
For the students at the Air Force Academy, the researchers are blessed with the rigid curriculum and protocol of a military college, ruling out most complications. Cadets face a heavy slate of compulsory first-year courses, including a battery of science, technology, engineering, and math requirements, and within each science-related course, students are randomly assigned to one of several teaching faculty members. So whether a student—male or female—was taught by a woman was a matter of luck rather than any active choice by student or professor. Each class used an identical syllabus and all students took the same exam, which prevented the various instructors from adjusting their courses to cater to better or worse students. Further, since the researchers also had access to students' math SAT scores, they could take account of any differences in quantitative abilities among the students.
The authors found that women on average obtain scores that are 0.15 grade points lower (half the difference between an A and an A-) than their male classmates, even after accounting for students' SAT scores. The gap in performance was widest for women taught by men. When a female instructor was put at the front of the classroom, nearly two-thirds of the grade point gender gap evaporated. (It was also the case that men performed better when taught by other men, but the difference was far less substantial.) The authors persuasively demonstrate that the overall male-female performance difference is due in large part to the fact that men dominate the Air Force Academy science faculty (as is the case in most schools), with only 23 percent of courses taught by women.