Originally Posted by Bostonian
I think grade equivalent scales and mental ages are as important as z-scores. Suppose the distribution of intelligence were much more compressed than it actually is, so that only 1% of 10-year-olds were as smart as the average 11-year-old. You could still create IQ scores with mean 100 and standard deviation of 15, but the need to make special accommodations for children with IQ of 130 would not be so urgent, because they would not be that much smarter than the average child their age. When, in reality, 10yo children with IQ of 130 are about as smart as average 13-year-olds, this suggests the need for accommodations.

No. When a six year old ceilings out on a subtest, the result puts them at 16 yo equivalent (from memory, paperwork is in sleeping child's room). And that's just not correct.