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.
Thanks.
[0] https://en.wikipedia.org/wiki/Flynn_effect#Possible_end_of_p...
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.
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!
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.
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.
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?
(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.)
> (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.