It's probably more accurate to say that IQ is a useful indicator of many specific cognitive deficits, and basically unuseful within or above 2SD of the center.
There are huge qualitative differences between cognitive ability between pairs of people within that range, but IQ stops accurately selecting the more capable of the two. It gets worse as the scores get higher. IQ is not a ranking of cognitive ability.
It's probably more accurate to say that IQ is a useful indicator of many specific cognitive deficits, and basically unuseful within or above 2SD of the center.
No. even within 1SD there are huge qualitative differences in what people are capable of.
There are huge qualitative differences between cognitive ability between pairs of people within that range, but IQ stops accurately selecting the more capable of the two. It gets worse as the scores get higher. IQ is not a ranking of cognitive ability.
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