Interesting Research Alert: Girls and Math

There is a theory explaining why there are so few women in the highest levels of math and science which is very comforting to scientists (see Larry Summers) looking to justify the persistent gap which remains many decades after the 'women's lib' movement.  Its quite simple.  You posit that on average there is no difference between the ability to do math and science of men and women (the means are the same), however, men vary more in their ability so there are more really smart men than really smart women.  Let's look at the figure below and take the X axis to be math ability, with 0 being average and the Y axis to be the probability for a person to have X ability in math. This theory says that, contrary to what people thought in the dark ages (pre women's lib), women's ability in math is not described by the green curve, and men's ability is described by the blue curve.  Rather, they believe that women's ability is described by the blue curve and men's ability is described by the red curve.   You see that the red curve is higher than the blue curve for values of X greater than .7, i.e. there are more men than women who are .7 in ability greater than the average, while the mean value of both distributions are 0. 

image from wikipedia

Some people say that both men and women are described by the blue curve for values of X which are less than 1, but for values greater than 1, the men's curve is enhanced so that the 'tails' of the distribution are higher for men.

Some new research from economists at MIT suggests that this simple theory does not hold.  Part of the motivation for the theory I outlined above is that not only are there very few women in the highest levels of academic math and science, there are also very few girls performing at the highest math levels in high school.  The researchers, as described in this article, focused on those top math student by looking at the results from the past 60 years of American Mathematics Competitions (AMC) contest, a math exam taken by some 125,000 "exceptional high school students".  They found that there were 4 boys for every 1 girl in the top 94% and in the top 99.9% that gap increased to 12 to 1.  However, suspecting that environment rather than innate ability might explain these results, they looked at the distribution by school of the highest performing students, those competing in the International Math Olympiad.  They found that while the boys were distributed over approximately 200 high schools, the girls came from just 20 schools.  In their words, "the gender gap at the very highest levels is in part due to extreme selection effects". 

I've skimmed through the paper, and it presents a more complicated picture than what is outlined in the article.  For example, while they found variation among high schools in the AMC sample, it was barely statistically significant, which might lessen the claim for environmental bias.  In any case, they say they do not want to draw conclusions, although they make broad but non committal statements about girls susceptibility to peer pressure and say their results aren't inconsistent with the 'men vary more in their ability' argument.  It's a murky field but what it can be said that there are persistent gender differences at the highest levels of math but that clearly there are some environmental factors at work.

The Universality of the Biological Clock

image from Softpedia

Biological clocks are often blamed for the dearth of women in the faculty ranks of STEM (science, technology, engineering and math) disciplines. The argument is that women want to have babies and view the academic life as incompatible with motherhood so the drive to reproduce forces them out of the field. Certainly there is some truth to this argument. Academia does not look kindly on those who do not spend every waking minute of their pre-tenure career working and I'm told that bearing and raising children takes a non negligible amount of time. However, a new study presented at a recent American Chemical Society meeting and reported on by Inside Higher Ed, shows that some graduate programs in chemistry place many more women in faculty positions than others, casting doubt on the dominance of the biological clock effect.

The study looked at the faculties of the top 94 chemistry departments and found that about 50% of the faculty members hired between 1994 and 2003 came from 12 graduate programs. They then looked at the number of men and women each of those 12 programs supplied to those top 94 chemistry departments. The variation across campuses was astonishing. Berkeley educated 31 male and 21 female chem professors whereas 32 male but only 2 women graduated from Harvard. MIT fared similarly poorly, supplying 30 male and only 6 female faculty members. The effect was diluted when they looked at the institution where these faculty members did their post doctoral work, but in general women from West Coast post docs fared better than their East Coast counter parts.

So, what happens to the biological clock explanation when confronted with these numbers? As the study author, Valerie J. Kuck, points out, "the women at Berkeley have the same biological clocks as other women, but they are getting jobs." So if we postulate that the biological clock is universal, that there isn't something in Berkeley's water which inoculates it's women against the pull of motherhood, then we must acknowledge that there is some other effect that is contributing to the loss of women in the academic pipeline.

This loss, while small for physics, is a big problem for chemistry and it is termed the "leaky pipeline". At each step of the academic ladder, women leak out. As I talked about before, women obtain over 30% of the PhDs in chemistry but only about 15% of the faculty hiring pool. (In physics the faculty applicant pool is only a couple of percentage points lower than the PhD pool for women). This data seems to suggest that for some institutions the discrepancy might be even greater while others have learned to plug the leaks.

The study prompts a multitude of questions which more or less fall in the vein of "How does Berkeley do it? and why is Harvard failing its women?". That characterization of the questions might have some institutional bias (Go Bears!) in it but I think it's basically correct. Unfortunately neither the study nor the article have anwsers. I know that Berkeley's school of Chemistry founded the national chemistry women's honor society, Iota Sigma Pi, in 1907 and that it is quite active, hosting social events and career development workshops. Their 2008-2009 events include panels on choosing a research group, writing a resume and navigating academic and industry career paths. I was also interested in this workshop, which directly deals with a problem many intelligent women seem to face: Overcoming the Impostor Syndrome: How to Feel as Bright and Capable as Everyone Seems to Think You Are. (It's a whole 'nother can of blog posts.) I don't know if Harvard or MIT have similar organizations, but in comparison to the other women in science organizations I know about, the Berkeley ISP stands out as a well rounded, complete and effective organization. I suspect they have something to do with Berkeley's success in creating female academics.

I'd love to see a similar study for physics, but the numbers might be too small. In any case, this study, which I hope grows to a full publication, reminds us that we shouldn't become complacent and use biology as an excuse for the gender imbalance in the sciences.

Positive News on the Gender Front

The National Academies has recently released a report, Gender Difference at Critical Transitions in the Careers of Science, Engineering and Mathematics Faculty, which has found no evidence for bias against women in hiring or promotion at the faculty level in academia. In fact, in certain disciplines, women are more likely to be offered faculty positions than their male competitors.

Unfortunately the news wasn't all rosy. The study found that women are applying for positions at a lower rate than men, i.e. scientifically trained women were more likely to leave academia after grad school or post docs. However, they observed that women are more likely to apply for a position if there is a woman on the search committee. They also found that women spend longer as assistant professors and leave academia before obtaining tenure more frequently than male counterparts. But they also found that there were no significant differences in the success of male and female professors by looking at measures such as salary, grants awarded, publications and honors or national appointments. The one area where men slightly outdid women was rate of publication; in chemistry and math men published several percent more papers, in physics, civil engineering and biology there was no difference and in electrical engineering women published more than men. Another nice finding was that 'stopping the tenure clock', a choice to delay your tenure decision for a year for family care, did not degrade either men or women's chances of obtaining tenure.

Because of my own observations of academia I am not very surprised by the committees' findings. In general I haven't seen overt bias or discrimination but tensions between scientific and family life seem to draw women out of the field. Luckily work-life balance is getting more attention these days. I've skimmed the summary of the report and read an article about it in Science, where I poached the graph below. It might be worth a full read since it seems to be be somewhat contradictory to the conclusions of other reports, but in line with some others.

Oh Larry Summers: Gender Again

Oh Larry Summers, you poor man who was so brutally tossed out of Harvard by women who did not want to accept the fact that they were just not capable of top tier math and science, what do you have to say about this study? It's beautifully written up here so I'm not going to say more on the subject other than that for background Summer's speech is worth a read to understand how frustrated he made women in science and our supporters.

Gender and the Physics Teacher

A couple of interesting studies on the effect that the gender of the instructor has on science students were recently released. The first takes a look at the perceptions high school students have of their science teachers, the second examines the effect the gender of a professor has on the female student's probability of continuation in a science, math or engineering major. Both fascinating studies speak to the power that perception and expectation have in determining our self-potential.

The first study, lead by Zahra Hazari, a Clemson University professor of engineering and science education, examined biology, chemistry and physics teacher evaluations by 18,000 high school students. They found that although there was no difference in the success in college of students taught by males and those taught by females, the women teachers were rated more poorly than their male counterparts. Interestingly, in biology and chemistry only the male students underrated their women teachers, but in physics both boys and girls perceived their female teachers as less effective. As Geoffrey Potvin, another Clemson professor said, these data suggest that students 'have developed a specific sense of gender-appropriate roles in the sciences by the end of high school'. We see this bias reflected in the number of female college majors in the sciences. In 2005, women made up 52% of chemistry majors, 62% of biology majors, but only 21% of physics majors in the top 50 research universities*.

The second study, by professors at UC Davis and the Air Force Academy, investigates the effect of professor gender on the probability a freshman woman will major in science. They looked at the records of all of the approximately 9,000 Air Force Academy students who graduated between 2000 and 2007 for correlations between the gender of the entry level science course instructors and the probability for a student to choose a science major. At the Academy all students have to take the same classes, so it's an ideal environment to study gender effects, modulo the fact that it is a military institution with a significant history of gender problems. They found that while for women in general gender did not make a difference, women who scored higher than 700 on their math SATs were 26% more likely to major in the sciences if all their intro science teachers were women than if they were all men. There was no effect seen on the male students.

In concert these two studies show that by high school students have developed gender bias in perceptions of scientific aptitude but that putting the female students into contact with professional women scientists (i.e. professors) could reverse some of that bias. It would be very interesting to see the results of the second study divided by major. Would the effect be present in the physics students? At Berkeley there are 5 women active faculty out of about 65 total (or 6 out of 100 including the emeritus professors). The probability that one of them will teach an introductory level class any given semester is low. As an undergrad I never took a class taught by a female physics professor and out of all the classes I took at Berkeley, only 2 were taught by female faculty, one in math and one in anthropology. But, I started doing research in 2001 and in all of the years since I have only spent 2 with male advisors, so I have not lacked for women role models. (I also had my dad, who always supported my interest in science and gave me a working example of what a scientist does). I strongly believe that having role models is vital to increasing the representation of women in the sciences. To that end, I've been doing some outreach to elementary school students, but I'll write about that in another post.

Some have claimed that the lack of women scientists might simply be due to the fact that women don't have the 'aptitude' for science. Those hypotheses infuriate me given the volume of research, such as these studies above, which show profound societal influences of both the success and the perception of success of women in science. The aptitude argument is the easy way out. We don't have to confront bias if it is dictated by biology. Luckily, people have realized that increasing the number of women in science and technology is in our national interest, and are working hard to see it happen.


* I should note that between 1996 and 2005 women recieved only 32% of chemistry PhDs and 46% of biology PhDs while 14% of physics PhDs went to women. In chemistry and biology there is a leaky pipeline--they loose women at every step of the ladder. In physics the pipeline problem is minimal, but we have a source problem--not enough women start in the first place.