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Is it all because more students take the test? Reports of falling IQ scores in many developed countries have been pretty well documented. Perhaps it is starting

Is it all because more students take the test? Reports of falling IQ scores in many developed countries have been pretty well documented. Perhaps it is starting to happen in the US also.

pmart123 7y ago
I believe IQ scores are rising still for lower scores, but falling for the top 1-2%?
- gwern 7y ago
  The very most recent US Flynn effect study finds the opposite pattern, actually (falling for low end, rising for high end): https://www.gwern.net/docs/iq/2019-platt.pdf https://www.gwern.net/docs/iq/2019-platt.pdf Personally, I don't buy it. The Flynn effect is large enough, and the way the normal distribution works with tail effects, that if there were any Flynn effect in general (much less focused on the high end), that you should see dramatic effects like several-fold increases in the number of perfect SAT scores. You don't see anything remotely like that - even despite loads of countervailing factors like increases in SAT access and prep!
  - SamReidHughes 7y ago
    Intelligence isn’t normally distributed though. E: And even if it was, and was capable of “shifting” left or right, which is a nonsensical notion about populations, a shift of a few IQ points wouldn’t have a dramatic many-fold increase in perfect scores.
    - gwern 7y ago
      You're right, intelligence, like anything else (eg height), is not exactly normally distributed: it has fatter tails than a normal distribution - so a shift in the mean would increase the density at a high threshold even more than you would calculate based on a normal.
      - SamReidHughes 7y ago
        No, a fat tail would do just the opposite. A fat tail is where more points are far from the threshold. But it's a moot point because an increase of 2 points among people in the 99th percentile implies little about those in the 99.99 percenteth quantile. Some description of a fat tail from 60-99 percentile doesn't say much about the top one percent. At a certain point, the dating market tops out.
        pmart123 7y ago
        I believe it is the same case with height. https://www.johndcook.com/blog/2008/07/20/why-heights-are-not-normally-distributed/ https://www.johndcook.com/blog/2008/07/20/why-heights-are-no... It's close to a normal distribution one or even two deviations away from the mean, but real-life has way more samples appearing +5 deviations away from the mean. I haven't really looked into it ever, but this could be because of a positive skew versus a distribution with purely fat tails?
        SamReidHughes 7y ago
        The difference is, it's easy to make a long-boned freak or a blithering idiot. But there's no hormone (I know of) that makes you a genius. (Also, intelligence/aptitude/performance scales like IQ, SAT, or ASVAB scores are arbitrarily numbered, so I'm don't know what a "fat tail" means in that respect. Maybe there's a standard definition that isn't completely arbitrary.)
        gwern 7y ago
        No, it would. Simulate it at a threshold like 1600 scores. The steeper increase in that part of the range yields the same phenomenon as normals. > (Also, intelligence/aptitude/performance scales like IQ, SAT, or ASVAB scores are arbitrarily numbered, so I'm don't know what a "fat tail" means in that respect. Maybe there's a standard definition that isn't completely arbitrary.) Er, you can look at plenty of cardinal-scaled things like vocabulary or digit span. Doesn't change the non-normality at the tails.
skolos 7y ago
Could you please provide references to these "pretty well documented" studies? Thanks.
- losvedir 7y ago
  I believe they're referring to the reversal of the Flynn effect[0]. [0] https://en.wikipedia.org/wiki/Flynn_effect#Possible_end_of_progression https://en.wikipedia.org/wiki/Flynn_effect#Possible_end_of_p...
- kypro 7y ago
  https://www.gwern.net/docs/iq/2016-dutton.pdf https://www.gwern.net/docs/iq/2016-dutton.pdf https://www.nbcnews.com/think/opinion/iq-rates-are-dropping-many-developed-countries-doesn-t-bode-ncna1008576 https://www.nbcnews.com/think/opinion/iq-rates-are-dropping-... This is fairly well documented. Average IQ scores in France have been declining a couple of points per decade if I recall correctly... I believe mass immigration from low IQ countries and dysgenics are often sourced as two of the potential reasons. But I have no idea how true that is.
  - mamayoyox 7y ago
    On hypothesis is that strong/indepdent women prefer someone who they can control and they marry immigrants or men with lower IQ ability (hence less desire for autonomy and personal freedom) which reduces overall IQ of the population SAT is just proxy for IQ. Many of my female friends who are at job and are indepdent are marrying wallmart guys (who are good looking but don't have good job)

Is it all because more students take the test? Reports of falling IQ scores in many developed countries have been pretty well documented. Perhaps it is starting to happen in the US also.

pmart123 7y ago

I believe IQ scores are rising still for lower scores, but falling for the top 1-2%?

gwern 7y ago
The very most recent US Flynn effect study finds the opposite pattern, actually (falling for low end, rising for high end): https://www.gwern.net/docs/iq/2019-platt.pdf https://www.gwern.net/docs/iq/2019-platt.pdf Personally, I don't buy it. The Flynn effect is large enough, and the way the normal distribution works with tail effects, that if there were any Flynn effect in general (much less focused on the high end), that you should see dramatic effects like several-fold increases in the number of perfect SAT scores. You don't see anything remotely like that - even despite loads of countervailing factors like increases in SAT access and prep!
- SamReidHughes 7y ago
  Intelligence isn’t normally distributed though. E: And even if it was, and was capable of “shifting” left or right, which is a nonsensical notion about populations, a shift of a few IQ points wouldn’t have a dramatic many-fold increase in perfect scores.
  - gwern 7y ago
    You're right, intelligence, like anything else (eg height), is not exactly normally distributed: it has fatter tails than a normal distribution - so a shift in the mean would increase the density at a high threshold even more than you would calculate based on a normal.
    - SamReidHughes 7y ago
      No, a fat tail would do just the opposite. A fat tail is where more points are far from the threshold. But it's a moot point because an increase of 2 points among people in the 99th percentile implies little about those in the 99.99 percenteth quantile. Some description of a fat tail from 60-99 percentile doesn't say much about the top one percent. At a certain point, the dating market tops out.
      - pmart123 7y ago
        I believe it is the same case with height. https://www.johndcook.com/blog/2008/07/20/why-heights-are-not-normally-distributed/ https://www.johndcook.com/blog/2008/07/20/why-heights-are-no... It's close to a normal distribution one or even two deviations away from the mean, but real-life has way more samples appearing +5 deviations away from the mean. I haven't really looked into it ever, but this could be because of a positive skew versus a distribution with purely fat tails?
        SamReidHughes 7y ago
        The difference is, it's easy to make a long-boned freak or a blithering idiot. But there's no hormone (I know of) that makes you a genius. (Also, intelligence/aptitude/performance scales like IQ, SAT, or ASVAB scores are arbitrarily numbered, so I'm don't know what a "fat tail" means in that respect. Maybe there's a standard definition that isn't completely arbitrary.)
      - gwern 7y ago
        No, it would. Simulate it at a threshold like 1600 scores. The steeper increase in that part of the range yields the same phenomenon as normals. > (Also, intelligence/aptitude/performance scales like IQ, SAT, or ASVAB scores are arbitrarily numbered, so I'm don't know what a "fat tail" means in that respect. Maybe there's a standard definition that isn't completely arbitrary.) Er, you can look at plenty of cardinal-scaled things like vocabulary or digit span. Doesn't change the non-normality at the tails.

skolos 7y ago

Could you please provide references to these "pretty well documented" studies? Thanks.

losvedir 7y ago
I believe they're referring to the reversal of the Flynn effect[0]. [0] https://en.wikipedia.org/wiki/Flynn_effect#Possible_end_of_progression https://en.wikipedia.org/wiki/Flynn_effect#Possible_end_of_p...
kypro 7y ago
https://www.gwern.net/docs/iq/2016-dutton.pdf https://www.gwern.net/docs/iq/2016-dutton.pdf https://www.nbcnews.com/think/opinion/iq-rates-are-dropping-many-developed-countries-doesn-t-bode-ncna1008576 https://www.nbcnews.com/think/opinion/iq-rates-are-dropping-... This is fairly well documented. Average IQ scores in France have been declining a couple of points per decade if I recall correctly... I believe mass immigration from low IQ countries and dysgenics are often sourced as two of the potential reasons. But I have no idea how true that is.
- mamayoyox 7y ago
  On hypothesis is that strong/indepdent women prefer someone who they can control and they marry immigrants or men with lower IQ ability (hence less desire for autonomy and personal freedom) which reduces overall IQ of the population SAT is just proxy for IQ. Many of my female friends who are at job and are indepdent are marrying wallmart guys (who are good looking but don't have good job)