[myg204]

If one considers intelligence (or other features) as the sum of many random sources, then it makes sense again to invoke the CLT. Maybe that's what the article implied.

[edit: see other replies saying the same thing below]

[leni536]

"Intelligence" itself is not a well defined quantity like height or weight. IQ is well defined but it is defined to follow a bell curve, it has nothing to do with CLT.

[gwern]

Intelligence is a well-defined quantity like temperature, and it follows a genetic architecture like height: thousands of genetic variants of small effect size. Which setup does indeed give you a binomial or normal sort of distribution, justifying the norming as more than a mathematical convenience.

[leni536]

>Which setup does indeed give you a binomial or normal sort of distribution

distribution of what? Still no quantity defined.

>Intelligence is a well-defined quantity like temperature

As a physicist it sounds about right. Temperature is tricky to define in non-stationary systems (aka. "real world").

[myg204]

As per wikipedia: "An intelligence quotient, or IQ, is a score derived from one of several standardized tests designed to assess human intelligence. "

I fail to see how IQ is "defined to follow a bell curve" as you wrote. The tests were designed so the answers distribution is a bell curve?

In my statement above, just replace "Intelligence" by "IQ", I believe that's what being discussed.

In any case, "Intelligence" can takes a thousand forms that I don't think IQ tests or even our vocabulary can really pin down.

[leni536]

As per wikipedia:

"When current IQ tests are developed, the median raw score of the norming sample is defined as IQ 100 and scores each standard deviation (SD) up or down are defined as 15 IQ points greater or less"

Raw test scores are transformed so the test results distribute on a bell curve. Can't find a more precise definition though.