Although it is my fond hope that “Psychological Comments” is becoming widely known, at least in the highly discerning circles inhabited by my distinguished readers, I sometimes wonder whether it would have been more accurate to call it “Supplementary Annexes”. As you will discern, I am not good at dreaming up best-selling brand names. However, the answer to interesting questions about scientific findings are often buried in supplementary annexes. The authors are not to be blamed for space limitations, though sometimes important matters are consigned to dark corners, and readers have to dig a little.
Who are the eminent persons who get very high scores at age 13 on tests which most 18 year olds find very difficult?
Here is the relevant table S1 in Supplementary Annex 1 to the paper by Makel et al. described in my previous posting.
First, as regards the sex ratio, in the TIP sample we have 215 men to 44 women, and in the SMPY sample 253 men to 67 women, so 81% of the overall sample are male, and 19% women, and the sex ratio is 468:111 or 4.22 to 1.
My view on this finding is that:
1) According to the Lynn hypothesis, males are late developers, so at 13 years of age sex differences in ability should be very small, but in maturity there will be a 4 IQ point male advantage. It would be good to look at the Verbal versus Maths scores (probably to be found in previous publications by these same authors) but in this case the male advantage is already evident at age 13.
2) Overall sex differences of this magnitude are closest to what we get by assuming that Males are IQ 102(15) and Females IQ 98(14) and assuming that the cut-off is IQ140. At this level 0.56% of men make the cut and 0.13% of women: the sex ratio is 4.18. That means that 81% of bright people will be men. This is a good match with these actual results.
However, it is pretty clear that these particular students are in the top 1 in 10,000, so the IQ equivalent is 155. At that level, to get a 4.2 sex ratio we get closest by assuming Males are IQ101(15) and Females IQ100(14). The issue of sex differences is not perfectly resolvable at the moment, because neither of these two talent searches will have found all the bright persons at that age (though I bet they will have found most of them), and the population of Scottish 11 year old shows an actual 8 to 1 sex ratio for the top scorers. However, the Scottish population data is a population N which takes precedence over a sample s. Nevertheless, both are highly informative
The data on ethnicity are rather sparse, but we can do a little bit of work on them by looking at US Census figures for the 1970s when most of these children were born.
White 178,119,221 Eminents 418 Rate .0000023467
Black 22,539,362 Eminents None stated.
Asian 1,526,401 Eminents 126 Rate .000082549
So, in the absence of more detailed particulars about the Other category, Asians win the race by a country mile. If we simplify things by considering only Whites, Blacks and Asians the US in 1970 then the country at that time was 88% White, 11% Black, and less than 1% Asian. The actual results of eminent students are 77% White, 0% Black, 22% Asian. No need for a Chi square.
In terms of eminence, Whites are somewhat under-represented, Blacks massively under-represented, Asians massively over-represented. We would need more detail about ethnic groupings before refining these numbers, but it is clear that some groups are far brighter than others, as intelligence testing reveals.
Another approach is to use the visualizer, putting Asians at IQ 106 (15) and Whites at IQ 100 (15) and the cut-off at IQ155. Then Asians achieve eminence 4.4 times more often than Whites.
Putting Blacks at IQ 85(15) against Whites IQ 100(15) then Whites achieve the eminence level 355 times more often. If we put Black IQ at 90 then Whites achieve the eminence level 74 times more often.
In general terms, the study of eminent minds identified at age 13 reveals significant male advantage, consistent with greater male variance and probably with somewhat higher male intelligence, though not conclusively. The study also reveals highly significant Asian advantage over Caucasians, consistent with higher intelligence, and Caucasian advantage over Africans, as revealed by intelligence testing.