I don't know why this data has been missed or ignored, but tens of millions of teenagers, generally 17 or 18, who want to attend college take the SAT, administered by The College Board, and the resulting data stretches more than 60 years...The SAT is divided into a Verbal section, which covers every kind of language skill, and Mathematical, which is self explanatory....Over hundreds of millions of tests, boys are very slightly better than girls in language skills, but are markedly better in Math skills...On average, therefore boys are about 4 IQ points ahead of girls on average at that age...This correlates well with the brain growth theory...
There are a few states where everybody takes SATs, and there's no sex difference in those states. Maybe this means there is no real difference, and it's selection bias. Or maybe this means they engineered the SAT to not show a gap. The ETS never publishes anything detailed about their psychometrics or test construction, so there's little way to know.
Is the SAT representative of the entire population? No..but that only matters if kids intending or hoping to go to college develop their mental powers in different ways from the rest of the population….Which I think is highly unlikely…In my experience as a student, teacher and parent, I agree that 1st grade girls are at least as smart as the boys..Indeed, some are very clever indeed…but at the high school level there starts to be some divergence, particularly in science and math, because the differential otherwise is minuscule….Anyway, it’s a huge data base, which also shows a serious decline in the abilities of college. bound students which has not yet abated….and that is showing up at all levels in the US…,
> but that only matters if kids intending or hoping to go to college develop their mental powers in different ways from the rest of the population….Which I think is highly unlikely…
You're going to need to elaborate, or that statement will be total nonsense. Obviously students planning to go to college experience, and have experienced, different mental development compared to students not planning to go to college.
The SAT is a problematic sample because it is systematically unrepresentative. Particularly as you go farther back in time ("the resulting data stretches [back] more than 60 years"), the SAT is a sample of "people who are qualified to go to college", not of "people".
This makes it easy to explain any amount of male advantage on the SAT as the result of greater variability.
This range restriction is also why there were non-linear relationships between IQ and SAT scores that people thought were more problematic than they actually were. In more recent years, the relationship has been linear. In fact, it was largely linear as early as 1997.
Analyses on the impact of selection bias on sex IQ gap has been done before, as I noted in this paper "The issue of self-selection has been raised as a confounding factor in testing Lynn’s hypothesis because women are more likely than men to participate voluntarily in surveys. Dykiert et al. (2009) argued that Lynn’s developmental theory of sex difference is difficult to test properly due to selection bias that is more pronounced in adult samples, as children are easy to sample because all children must attend school while adults are more autonomous in their decisions: “Researchers must address the problem of non-inclusion of a proportion of their target population because there are systematic differences between those who choose to take part in studies and those who do not. These disparities may, and almost obviously do, bias the findings of studies on sex differences in intelligence, since it appears that both gender and intelligence may influence one’s decision to participate.” (p. 43). Their literature review, along with their analysis of the BCS, found evidence that attrition effects in follow-up waves caused a distortion in gender ratio, IQ means and variances, ultimately resulting in a higher female to male ratio, higher IQ for the remaining subjects, higher IQ variance for males, higher IQ means for males compared to females. Yet the sex IQ gap does not vary across ages, with a male advantage of 1.21, 1.79 and 1.39 IQ points at age 10, 26, and 30, respectively. A better method to estimate attrition is by way of logistic regression, proposed by Hunt & Madhyastha (2008), and which calculates the probability of participation in the follow-up depending on cognitive ability. Using this method, Madhyastha et al. (2009, Tables 3 & 6) analyzed the BCS and the NCDS data but found that the distortion, owing to differential attrition rates, on the male-female IQ is extremely small among adults. Even more troublesome is that Lynn & Kanazawa (2011, Tables 2-3) actually analyzed the NCDS among adolescents and found a very slight female advantage at age 7 and 11 but found a male advantage of 1.8 IQ points at age 16 as well as a consistently larger SD of males’ IQ regardless of age. Because the pattern is similar whether the entire sample at each wave is analyzed or whether a restricted sample that completed all surveys is analyzed, they effectively ruled out the attrition effect as a possible explanation for the developmental theory of sex differences. Taken together, it would seem that the impact of differential attrition is unlikely to account for much of the observed gender full scale IQ difference, because this gap typically amounts to 5 points (Lynn & Irwing, 2004).
Perhaps, as a result, there is no definitive conclusion on sex differences in general ability. Differences in age, attrition effect and methodology across samples, however, do not explain why there is a general agreement in sex differences in specific abilities but not in general ability (Reynolds et al., 2022)."
I had read somewhere that the IQ spread was wider in men than women, that there were more highly intelligent males than highly intelligent females, but that there were also more highly unintelligent males than highly unintelligent females.
This comports with my own observations, for what that's worth.
In other words the female sex is selected for proximity to the mean, but not so, or less so, men.
Alternatively, something to do with the vulnerability associated with having only one X chromosome, speculatively?
If we think brain size in humans has a causal impact on intelligence, the fact that height and brain size covary because both covary with maleness shouldn't affect the relationship between maleness and intelligence.
Maybe brain size relative to total mass or total volume has a causal impact on intelligence; I don't see by what mechanism that would be plausible, and if it's even borne out by the (human) within-sex data.
Well, are tall humans less smart relative to their brain size than small humans? If we already know that brain size predicts intelligence among humans, I would think we already have the data to answer that question.
As we discussed, you didn't use a correct specification for your IRT analyses in the NLSY. You conditioned on a scoring parameter, thus entering it into the model twice.
Use a proper model and it converges with the overall MGCFA results and an MGCFA of the parcel scores.
We should expect early female expression and later male expression for at least the following reasons:
0) The sexual division of labor, and risk, in time, and over time.
1) Maturity: the evolutionary utility of early female social and sexual maturity and later male political and sexual maturity.
2) Brains grow probabilistically they are not manufactured deterministically, and genetic (SNP) contribution to intelligence is enormously diverse, with sex differences in 'wiring' of neurons visible and obvious - overstated as distributive differences in hemispheric bias and hemispheric integration.
3) Processing bias: female prey, empathizing, in-time experience vs male predator systematizing, over-time, prediction.
4) The consequence of processing bias: systems over time are more complicated than experiences in time. Men are lean mean problem solving machines visible in response times with constant systemic awareness of the 'walls' of the population and the territory. Women evolved to keep track of the present state and maintain the present state of children first, other women second, and men third. In other words, women can keep track of whats in the pantry and the mental state of 'rug rats' and men can keep track of systemic risks. ;)
(Tried to close a serious subject with a bit of humor.). ;)
Plomin has found that the genetic influence on IQ increases across the lifespan. I am forgetting his specific interpretation, but basically some variant of genetic accumulation (e.g., active and evocative forces in which the environment slowly adjusts to reflect genetic tendencies). During childhood, children are forced to participate in schooling that strives to negate environmental differences, which means that we should expect that genetics plays a bigger role - yet the data shows the opposite, with girls > boys in IQ.
One possible solution, however, is that the school systems are dominated by women who invariably craft the schooling to female tendencies, putting boys at a disadvantage. Yes, IQ is supposed to be independent of educational achievement, but perhaps the boys being saturated in a female-directed world saps them of their enthusiasm for the intellect?
Over fifty years ago I read about the “empirical fact” that males and females are on average of equal general intelligence despite the larger size of the male brain (but with a flatter bell-curve distribution for men). I immediately noticed that, as males are more visuospatial and females are more verbal, there must have been a decision to weight the scores in order to produce that result. It seems more accurate to say that there are different types of intelligence and that the different types are not objectively commensurable.
Something that might play into the gap increasing with age is “pregnancy brain” and associated ills. It seems to be widely accepted folk knowledge that women lose a few points of IQ. Not sure if similar occurs at menopause.
I thought it has already been proven that spatial ability requires a greater volume of brain matter than other cognitive abilities. Arctic people have, on average, the largest brains of any human group while also having a profound spatial tilt alongside spatial abilities that aren't properly captured in conventional IQ tests. This is despite having a less than average IQ score (about 90) overall compared to populations with smaller average cranial capacities. I think Lynn should have realized this since he's basically written directly about it:
Starting on page 98 he gives an overview of the intelligence of Arctic peoples. He then basically repeats the visual-volume thesis on pages 100-101. He reasonably hedges by saying:
"It has only proved possible to find one study of the brain size of Arctic Peoples. Smith and Beals (1990) give brain sizes for ten populations of which the mean is l,444cc."
However, the general relationship has been replicated since:
Additionally, on a rather petty and less rigorous front, my prior is that Rushton is incorrect regarding any of his views of the past that strongly conflicted with the hereditarian consensus.
I don't know why this data has been missed or ignored, but tens of millions of teenagers, generally 17 or 18, who want to attend college take the SAT, administered by The College Board, and the resulting data stretches more than 60 years...The SAT is divided into a Verbal section, which covers every kind of language skill, and Mathematical, which is self explanatory....Over hundreds of millions of tests, boys are very slightly better than girls in language skills, but are markedly better in Math skills...On average, therefore boys are about 4 IQ points ahead of girls on average at that age...This correlates well with the brain growth theory...
There are a few states where everybody takes SATs, and there's no sex difference in those states. Maybe this means there is no real difference, and it's selection bias. Or maybe this means they engineered the SAT to not show a gap. The ETS never publishes anything detailed about their psychometrics or test construction, so there's little way to know.
Is the SAT representative of the entire population? No..but that only matters if kids intending or hoping to go to college develop their mental powers in different ways from the rest of the population….Which I think is highly unlikely…In my experience as a student, teacher and parent, I agree that 1st grade girls are at least as smart as the boys..Indeed, some are very clever indeed…but at the high school level there starts to be some divergence, particularly in science and math, because the differential otherwise is minuscule….Anyway, it’s a huge data base, which also shows a serious decline in the abilities of college. bound students which has not yet abated….and that is showing up at all levels in the US…,
> but that only matters if kids intending or hoping to go to college develop their mental powers in different ways from the rest of the population….Which I think is highly unlikely…
You're going to need to elaborate, or that statement will be total nonsense. Obviously students planning to go to college experience, and have experienced, different mental development compared to students not planning to go to college.
The SAT is a problematic sample because it is systematically unrepresentative. Particularly as you go farther back in time ("the resulting data stretches [back] more than 60 years"), the SAT is a sample of "people who are qualified to go to college", not of "people".
This makes it easy to explain any amount of male advantage on the SAT as the result of greater variability.
This range restriction is also why there were non-linear relationships between IQ and SAT scores that people thought were more problematic than they actually were. In more recent years, the relationship has been linear. In fact, it was largely linear as early as 1997.
Now why would a male advantage or a black disadvantage be ignored? ;)
Analyses on the impact of selection bias on sex IQ gap has been done before, as I noted in this paper "The issue of self-selection has been raised as a confounding factor in testing Lynn’s hypothesis because women are more likely than men to participate voluntarily in surveys. Dykiert et al. (2009) argued that Lynn’s developmental theory of sex difference is difficult to test properly due to selection bias that is more pronounced in adult samples, as children are easy to sample because all children must attend school while adults are more autonomous in their decisions: “Researchers must address the problem of non-inclusion of a proportion of their target population because there are systematic differences between those who choose to take part in studies and those who do not. These disparities may, and almost obviously do, bias the findings of studies on sex differences in intelligence, since it appears that both gender and intelligence may influence one’s decision to participate.” (p. 43). Their literature review, along with their analysis of the BCS, found evidence that attrition effects in follow-up waves caused a distortion in gender ratio, IQ means and variances, ultimately resulting in a higher female to male ratio, higher IQ for the remaining subjects, higher IQ variance for males, higher IQ means for males compared to females. Yet the sex IQ gap does not vary across ages, with a male advantage of 1.21, 1.79 and 1.39 IQ points at age 10, 26, and 30, respectively. A better method to estimate attrition is by way of logistic regression, proposed by Hunt & Madhyastha (2008), and which calculates the probability of participation in the follow-up depending on cognitive ability. Using this method, Madhyastha et al. (2009, Tables 3 & 6) analyzed the BCS and the NCDS data but found that the distortion, owing to differential attrition rates, on the male-female IQ is extremely small among adults. Even more troublesome is that Lynn & Kanazawa (2011, Tables 2-3) actually analyzed the NCDS among adolescents and found a very slight female advantage at age 7 and 11 but found a male advantage of 1.8 IQ points at age 16 as well as a consistently larger SD of males’ IQ regardless of age. Because the pattern is similar whether the entire sample at each wave is analyzed or whether a restricted sample that completed all surveys is analyzed, they effectively ruled out the attrition effect as a possible explanation for the developmental theory of sex differences. Taken together, it would seem that the impact of differential attrition is unlikely to account for much of the observed gender full scale IQ difference, because this gap typically amounts to 5 points (Lynn & Irwing, 2004).
Perhaps, as a result, there is no definitive conclusion on sex differences in general ability. Differences in age, attrition effect and methodology across samples, however, do not explain why there is a general agreement in sex differences in specific abilities but not in general ability (Reynolds et al., 2022)."
I had read somewhere that the IQ spread was wider in men than women, that there were more highly intelligent males than highly intelligent females, but that there were also more highly unintelligent males than highly unintelligent females.
This comports with my own observations, for what that's worth.
In other words the female sex is selected for proximity to the mean, but not so, or less so, men.
Alternatively, something to do with the vulnerability associated with having only one X chromosome, speculatively?
Larger male variance is well documented (Larry Summers still got fired for saying this though).
I think being fired by those people is something that can only improve one's c-v.
Unless you're looking for work as a university president or something.
Great to see this result. Also, why “control” for height? Being taller might require cerebellar power, but not a bigger cortex
Whales have bigger brains than humans but humans are smarter, we don't usually think of intelligence as relating to mere absolute brain size.
If we think brain size in humans has a causal impact on intelligence, the fact that height and brain size covary because both covary with maleness shouldn't affect the relationship between maleness and intelligence.
Maybe brain size relative to total mass or total volume has a causal impact on intelligence; I don't see by what mechanism that would be plausible, and if it's even borne out by the (human) within-sex data.
Well, are tall humans less smart relative to their brain size than small humans? If we already know that brain size predicts intelligence among humans, I would think we already have the data to answer that question.
As we discussed, you didn't use a correct specification for your IRT analyses in the NLSY. You conditioned on a scoring parameter, thus entering it into the model twice.
Use a proper model and it converges with the overall MGCFA results and an MGCFA of the parcel scores.
Doesn't make any sense to me.
A note on causality.
We should expect early female expression and later male expression for at least the following reasons:
0) The sexual division of labor, and risk, in time, and over time.
1) Maturity: the evolutionary utility of early female social and sexual maturity and later male political and sexual maturity.
2) Brains grow probabilistically they are not manufactured deterministically, and genetic (SNP) contribution to intelligence is enormously diverse, with sex differences in 'wiring' of neurons visible and obvious - overstated as distributive differences in hemispheric bias and hemispheric integration.
3) Processing bias: female prey, empathizing, in-time experience vs male predator systematizing, over-time, prediction.
4) The consequence of processing bias: systems over time are more complicated than experiences in time. Men are lean mean problem solving machines visible in response times with constant systemic awareness of the 'walls' of the population and the territory. Women evolved to keep track of the present state and maintain the present state of children first, other women second, and men third. In other words, women can keep track of whats in the pantry and the mental state of 'rug rats' and men can keep track of systemic risks. ;)
(Tried to close a serious subject with a bit of humor.). ;)
Cheers
CD
NLI
Plomin has found that the genetic influence on IQ increases across the lifespan. I am forgetting his specific interpretation, but basically some variant of genetic accumulation (e.g., active and evocative forces in which the environment slowly adjusts to reflect genetic tendencies). During childhood, children are forced to participate in schooling that strives to negate environmental differences, which means that we should expect that genetics plays a bigger role - yet the data shows the opposite, with girls > boys in IQ.
One possible solution, however, is that the school systems are dominated by women who invariably craft the schooling to female tendencies, putting boys at a disadvantage. Yes, IQ is supposed to be independent of educational achievement, but perhaps the boys being saturated in a female-directed world saps them of their enthusiasm for the intellect?
Over fifty years ago I read about the “empirical fact” that males and females are on average of equal general intelligence despite the larger size of the male brain (but with a flatter bell-curve distribution for men). I immediately noticed that, as males are more visuospatial and females are more verbal, there must have been a decision to weight the scores in order to produce that result. It seems more accurate to say that there are different types of intelligence and that the different types are not objectively commensurable.
Sorry, a basic question. What does the (C) refer to in the table which shows the subjects that men or women thrive in?
Something that might play into the gap increasing with age is “pregnancy brain” and associated ills. It seems to be widely accepted folk knowledge that women lose a few points of IQ. Not sure if similar occurs at menopause.
I thought it has already been proven that spatial ability requires a greater volume of brain matter than other cognitive abilities. Arctic people have, on average, the largest brains of any human group while also having a profound spatial tilt alongside spatial abilities that aren't properly captured in conventional IQ tests. This is despite having a less than average IQ score (about 90) overall compared to populations with smaller average cranial capacities. I think Lynn should have realized this since he's basically written directly about it:
https://lesacreduprintemps19.wordpress.com/wp-content/uploads/2012/11/lynn-race-differences-in-intelligence.pdf
Starting on page 98 he gives an overview of the intelligence of Arctic peoples. He then basically repeats the visual-volume thesis on pages 100-101. He reasonably hedges by saying:
"It has only proved possible to find one study of the brain size of Arctic Peoples. Smith and Beals (1990) give brain sizes for ten populations of which the mean is l,444cc."
However, the general relationship has been replicated since:
https://pmc.ncbi.nlm.nih.gov/articles/PMC3259958/
Additionally, on a rather petty and less rigorous front, my prior is that Rushton is incorrect regarding any of his views of the past that strongly conflicted with the hereditarian consensus.
Hm, if IQ correlates with brain size, and brain size with height, taller people should have a higher IQ. Or is brain size a proxy for something else?
Taller people are indeed a bit smarter within a population.