Differences in sex differences: US trends and India

 

Sex differences fascinate, but would be easier to understand if only they would stand still for a moment! Reported sex differences vary in magnitude, 3 to 1, or 4 to 1, or 7 to 1.

As usual, it depends on the representativeness of samples, the abilities being measured, and also how far out on the right hand side of the bell curve you go when you measure the man/woman ratio of high achievers. In the early 1980s on the SAT-Math the sex ratio was approximately 2 to 1 for scores ≥500 (top 0.5%) and roughly 13 to 1 for students scoring ≥700 (top 0.01%).

As Gigerenzer keeps pointing out, most people misunderstand the combination of decimal points and percentage signs. 0.5% means 1 in 200, or 5 in a thousand, or 50 in ten thousand.  0.01% is even more tricky: it is not a fifth but a fiftieth of 0.5%. It is 1 in 10,000. In sum, males are 2 to 1 at a level of ability reached by 50 out of 10,000 students, but at the very high levels achieved by 1 out of 10,000 students the male advantage is 13 to 1. At least, that was the picture in the 1980s. What are things like now?

Before that, here is some background:

Maths is a man thing. September 2013 https://drjamesthompson.blogspot.co.uk/2013/09/maths-is-man-thing.html

Advice to men caught unawares. November 2014

https://drjamesthompson.blogspot.co.uk/2014/11/advice-to-men-caught-unawares.html

The historical record is clear: eminent men predominate by at least 7 to 1 or, in Charles Murray’s “Human Accomplishment” 30 to 0 for the very top thinkers, people like Aristotle, Darwin, Galileo, Newton, Einstein (page 143) .  Women have the perfect alibi of motherhood, and as Larkin noted, sexual liberation did not come till after the Beatles’ first LP.

Sexual intercourse began.

In nineteen sixty-three

(which was rather late for me) -

Between the end of the "Chatterley" ban.

And the Beatles' first LP.

In fact, some liberation began in 1870 with the Education Act, more in 1914 with the First World War, more after the contraceptive pill in the early 1960s and more and more thereafter.  Although that is true about our own age, perhaps this story is wrong, a mere blip of epoch-centric bias, and denies the rights and the impact women had made centuries before.  Thirty wills survive today from the late Anglo-Saxon period and ten of those are the wills of women, each of whom was a significant property owner , with the same rights of ownership and bequeathal as any man.  Women were highly significant figures in Saxon history, and were admired for their power and nepotism, even if it involved the occasional murder. Interestingly, royal succession was not by primogeniture, but by classifying royal progeny as aethelings (throne-worthy) and from this gene pool the royal family would select the one who seemed best qualified for the job. Meritocracy within aristocracy. So, when pressure groups today want to force employers to appoint women to high offices, they should recall that, as a rule of thumb, in the year 1000 it  was already the case that about a third of the richest Saxons were women.

However, given the clamour for equality in modern times, surely the speed of women’s advance should be quickening?

The sex ratio in accomplishment depends on the skills being measured (harder subjects increase sex differences) and how accomplished you have to be to be judged accomplished (harder standards increase sex differences). So, if we go for Fields Medallists, the score is 55 to 1. Coming down slightly from those sorts of levels, how are young American men and women doing in Maths?

Matthew C. Makel, Jonathan Wai, Kristen Peairs, Martha Putallaz.  Sex differences in the right tail of cognitive abilities: An update and cross cultural extension. Intelligence Volume 59, November–December 2016, Pages 8–15

https://drive.google.com/file/d/0B3c4TxciNeJZZ3BoWHVmbGZKcGs/view?usp=sharing

In the Abstract they say: Male–female ability differences in the right tail (at or above the 95th percentile) have been widely discussed for their potential role in achievement and occupational differences in adults. The present study provides updated male–female ability ratios from 320,000 7th grade students in the United States in the right tail (top 5%) through the extreme right tail (top 0.01%) from 2011 to 2015 using measures of math, verbal, and science reasoning. Additionally, the present study establishes male-female ability ratios in a sample of over 7000 7th grade students in the right tail from 2011 to 2015 in India. Results indicate that ratios in the extreme right tail of math ability in the U.S. have shrunk in the last 20 years (still favoring males) and remained relatively stable in the verbal domain (still favoring females). Similar patterns of male-female ratios in the extreme right tail were found in the Indian sample.

They plot out the main US results in a dramatic graph.

 

The detailed results are in Table 1, so see what you think:

Look like sometime between 1996 and 2000 a new score category of 800 was added. Why? 700+ was good enough before. That category shows the biggest male advantage compared to the 700+ column. Looks like either a) students got brighter or b) the test got easier.

However, the EXPLORE-Math score did not show a decline. Whether earlier changes on some tests and the on-going stability in other tests can be explained by potential ceiling effects in the measure in this sample (see Wai et
al., 2012) or other reasons — (e.g., lack of time for any intervention, the effects of test makers purposefully “juking” tests to reduce demographic differences as suggested by Loewen et al., 1988) — is currently unknown

Well, this leaves a lot unknown. The drop in the sex ratio between 1980 and 1990 is enormous. Something must have happened. Crack teams must have fanned out across America, treating Maths anxiety among girls, and giving them special tuition. There must have been summer schools for the brightest girls. I have never seen such a speedy change in a scholastic indicator, and that includes the rise in language ability of first generation immigrants. It is not clear to me whether the authors believe in the change or not, which is a pity, because this is apparently one of the best findings showing that a cultural intervention can overcome an apparently deep-seated biological difference between the sexes. To give the authors their due, they mention that the tests may have been tampered with, so as to reduce sex differences, but they are the ones closest to the data, so I am sure they could tell us a little more. For example, given that this particular period is so extraordinary, why not plot out the results for each year? Big oscillations in the sex ratio during those years would be suggestive of cultural changes coming in, and taking time to spread through all schools. A sharp fall in a single year would suggest that the test had been revised in a major way. Which is it? What did the test makers say about sex differences over the years? Did they ever mention working on items to make sure they were not sex biased?

At the moment all I can think of is that US Maths tests prior to 1991 had the following statement in the instructions: ALL THE QUESTIONS IN THIS EXAM RELATE TO SPARK PLUGS.

Despite all this, as late a 2010 boys outshone girls at 7 to to 1 (actually 6.58 to 1, but I have rounded up for effect). On the ASSET test top score of 35 the ratio is 8 to 1.

It is minor gripe, but having got some great data from India, it was difficult to find it in their table. Please label the Indian results India. Saves time.

Have we yet another result which shows a biologically based male/female difference, which is also subject to strong cultural forces? I cannot be sure. I don’t know enough about the test content, and what questions may have been dropped because of presumed sex bias. I don’t know if the tests have become easier overall, but suspect it, since during recent years GCSEs in the UK became much easier in terms of the overall pass rate, and are now becoming slightly harder again. Test constructors are under pressure to make sure that their tests are fair, and the concept of fair mitigates against finding sex differences, as well as the more familiar race differences.

Despite my uncertainties, this is a good paper, on a very sizeable population of test takers in the US and in India. In my view the authors have not mined the Indian material very much. Surely in these disparate US and Indian tests there must be some very similar test items which would allow a proper comparison between US and India. The authors do some comparisons which assume US intelligence is identical to India, which null hypothesis I think can be discarded. Time for them to team up with Richard Lynn and see if they can do more work on the sex ratios in different Indian provinces, which are extremely heterogeneous in terms of general ability. Not sure what my prediction about sex ratios would be: the brighter the province the higher the sex ratios?

https://drjamesthompson.blogspot.co.uk/2015/03/the-heterogeneous-states-of-india.html

Overall, an intriguing finding, strongly suggesting a change in the sex ratio for Maths, but with relevant points still unanswered. Some specific item analyses could be highly informative.

I have already hinted that I know of work which links intelligence to measured brain volumes of men and women, finding brain size to be a good predictor of sex differences, but that paper is only just now going before reviewers, so whereof one cannot speak one must remain silent.

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