Wednesday, November 02, 2016

The collapsing math genius gender gap

Via Allison Schrager, Andy McAfee, and others, here comes a chart of the gender gap in upper-tail SAT scores:

As you can see, the ratio has drifted downward at all levels, but at the 0.01% level (about 3.7 standard deviations of the combined score distribution, if you assume normality) it has fairly dramatically collapsed. When Ronald Reagan was elected, girls made up only 7% of the top performers. By the time Clinton took office, it was 20%. As of Obama's reelection, it was 28%.

The key piece of information here isn't the current level of the gender gap, it's the recent rate of change. This sort of rapid shift implies that there's lots going on here that's not genetic - unless biological gender differences can change radically from decade to decade.

It's highly unlikely to be a change in the SAT math section. The SAT math section is the same damn thing year after year after year. "Do you know the ratio of sides of a 30-60-90 triangle?" "Can you factor a quadratic expression, using only a paper clip and bubblegum?" "What was the color of Napoleon's white horse?" And so on.*

If it ain't biology, and it ain't a measurement problem, it must be environmental forces that are causing the gender gap to collapse. And whatever these environmental forces are, they're strong stuff.

Knowing that strong environmental forces are present doesn't rule out inherited ability differences. It could be that there are two forces at work, and that the ratio will eventually settle into its "natural," biologically determined perfectly meritocratic level. But Occam's Razor - or really, any penalty term for model complexity - says that a one-factor model beats a two-factor, all else equal. In other words, if strong environmental forces were still present in 2006, it's a decent bet that they weren't completely gone as of 2011. So this doesn't kill the genetic-determinist position, but it weakens it.

OK, so who cares? Well, this is relevant to a recent Journal of Economic Perspectives article by Amanda Bayer and Cecilia Rouse, entitled "Diversity in the Economics Profession: A New Attack on an Old Problem". Bayer and Rouse show that the percentages of PhDs and undergrad degrees awarded to women in the econ field have remained flat for the past two decades:

What this says is that an econ degree isn't just an upper-tail IQ test. If it is, the gender gap would have shrunk since the days of Soundgarden and flannel shirts.

So what is causing the gender gap in econ? Preferences are one possibility. Maybe women just don't like econ as much as men. SAT scores are a great proxy for IQ, but they're a pretty terrible proxy for the desire to spend your life selling a bunch of skeptical colleagues on the merits of your own mildly challenging variation on a highly stylized benchmark model with poor data fit, or sifting through the historical record for plausibly exogenous natural experiments. There's no reason to expect math-geniuses to desire that life in strict proportion to their math-geniusy-ness.

Sociology is another possibility. The econ boys' club might be shutting out the ladies. Perhaps they're afraid that a girl will accidentally brush their arms at a seminar, infecting them with incurable icky girl-cooties. Knowing certain economists, I wouldn't be surprised if this is exactly their fear. Or maybe some women think econ has way too high a fraction of creepy libertarian dudes who will subtly try to sink their careers in a misguided attempt at revenge against the cheerleaders who wouldn't sleep with them in high school. Knowing certain economists, I wouldn't be surprised if this is exactly their fear.

So anyway, yes, I guess at the end of the day this is just another "Girls RULE!" post. Are we tired of "Girls RULE!" posts yet? Hell no. You know me. I never get tired of anything.

*Answers: 1. 1/2/sqrt(3), 2. Trick question, as we're all out of bubblegum, and 3. C


  1. My late wife blew up the CPA exam. Scored in the high 90's on all 4 sections. The CPA's got worried that the profession was becoming "womens work" so they added calculus as a requirement. The wife said all you need as a CPA was algebra.
    Yup, there is a bit of sexism left in the world.
    The worry was that with more women in the field wages would come down.

    1. Dilbert and Dogbert would tell you most of that sexism is directed against men.

    2. Anonymous8:19 PM

      Your wife is a accountant... What a smartie. Then, she knows more about economics than economists ignorant of accounting.

      Why do they not interview accounts on financial TV? That would be an improvement.

  2. Anonymous9:37 PM

    For whatever it's worth, I (without having followed the debate too closely before and thus formed a particularly strong opinion) used to be more sympathetic to a "mostly innate differences" explanation of the gender gap, but this is very strong evidence against that and makes me much more sympathetic to a "mostly and maybe entirely socialization" explanation.

    Also, on a semi-related note, I remember on Twitter dot com a few weeks or so ago you mocked Steve Sailer for noting that there sure are *a lot* of Jews in the economics profession, yet no one seems to think this represents a problem in terms of diversity. Because Twitter is IMO a horrible medium to hash out disagreements, I wanted to ask you here:

    What is your principled reason to see the under-representation relative to population share of women and non-Asian minorities as a problem that is caused partially by discrimination, unfair to those groups and hinders the economics profession, but not the under-representation of gentiles? To be clear, my own view on the subject is that there's really nothing wrong with whites, men and/or Jews being over-represented in certain prestigious fields; I'm glad that people from those groups contribute so much to society. But it seems like you and a lot of other liberal and leftist people think that it's a big problem that whites and men are so highly represented among certain groups of high achievers, but not such a big problem that Jews are, which seems kind of inconsistent.

    1. Hmm. Well, speaking as a sort of Jew myself, I do kind of wish that more Jewish folks would ditch econ and go do something useful with their lives!! :-)

      But anyway, I can't really speak for other people, but personally, I've seen a number of male economists be dicks to women in the profession - saying insulting stuff, discounting their potential, their skill, and their ideas, and just generally being bullies. On the other hand, I've never seen Jewish economists bully non-Jewish economists (except in the case where it was a Jewish man being sexist towards a non-Jewish woman). So that didn't strike me as a problem.

      I also have witnessed essentially no racism against Black people in the econ profession, but considerable racism toward Asian people. This is just my anecdotal experience, of course. But it makes me suspect that maybe Asians are being systematically underrepresented in econ, and I think someone should look into it...

      But basically, I'm usually only concerned with people treating other people badly, not with statistical representation per se. Does that answer your question? Again, I'm only speaking for myself here.

    2. Oh, and mocking Steve Sailer is the Lord's work, I refuse to believe otherwise... ;-)

    3. Anonymous8:14 AM

      Yeah, that makes a lot of sense to me, thanks for answering my question.

    4. I think it is the subjective nature of current economics and the self-reinforcing masculine slant. It's pervasive and quite evident to women. Just one example: the focus on GDP when it excludes all unpaid work, typically performed by women.

    5. What kind of Jews? Arab jews? Beta Israel jews? Or European Jews in the US? European Jews in the US are probably over-represented due to standard privilege.

      It's weird that the white nationalists see a jewish conspiracy then basically support it with standard privilege analysis.

    6. Noah, if you are just sort of a Jew, you are Jew-ISH. Not really all that smart.

      Speaking of smart Jews, does this mean that Larry Summers is dumb and not just sexist? I was shocked you did not mention him by name, especially as you measured the ratios among the elite. But I'm a Catholic, so I might have missed the reference.

    7. Anonymous8:36 PM

      Mary Robinson,

      What a great point! Oh, GDP is so flawed.

      (And, on the flip side, many people also ignore, that GDP it includes also destructive activities as a positive count as well.)

  3. Anonymous4:10 PM

    Is it the same for 12th graders? And people who participate in US Math Olympiad? Do we have data for those? Or are they obviously the same so we don't need to look further? And if the data aren't the same as for the 7th graders, what do you think the reasons are (for the differences)?

  4. Anonymous8:29 PM

    I'm not sure Econ helps IQ at all.

  5. Well, the problem with girls is that they are too risk averse as the history of civilizations and persistent victories of patriarchy show.

    So the possible future with Yay girls! is low innovation (both good and bad) and slow growth. Maybe we are already living it.

  6. Anonymous12:40 AM

    I don't really understand how you can blame libertarians for the under-representation issue, when the econ profession as a whole leans mildly left-wing. On the right, even Greg Mankiw is not a libertarian, you have to get to John Cochrane before finding an influential libertarian in econ today. I'm not accusing you personally, but plenty of people on the educated left exhibit effectively racist behavior when they find their own privileges being threatened ( If econ has too few minorities, you should look at the sub-culture that exercises the most influence rather than the least when guessing at assigning blame.

  7. Anonymous3:04 AM

    Hey Noah, given the election results, can you write a blog post saying everything is going to be ok? That'd be super nice

  8. Between your exclamation of "Girls RULE!" and your admission that you're out of bubblegum, I shouldn't be surprised that you illustrated this entry with the cast of "Bubblegum Crisis." I'm looking forward to your recycling the image when you talk about automation replacing people. After all, the series is about fighting rogue robots.

  9. Anonymous8:09 AM

    While I'm sure I'm not in the "genius" category, as someone who scored in the 99th percentile for the SAT math a very long time ago, I can tell you that when I majored in engineering at a small, conservative university, I was bullied and harassed, openly and not. I had a prof give me a B- for helping my fellow students, saying it was cheating, but the two men who were also at the front of that room being tutors got to keep their As (and if he really wanted to say we were cheating, he should have failed us). I don't know about now. I certainly hope it has changed a lot.