The
range of scores doesn't even go to three standard deviations above the mean, so at best even if it
isa proxy for IQ scores --- which I don't think it is --- the SAT has a very low ceiling at best.
IQ tests are normed on the general population, including the mentally retarded. The SAT is taken only by students applying to college, who are on average smarter than high school juniors and seniors in general (and who in turn are smarter than the population of 16- and 17-year olds, which includes drop-outs). I saw a study once showing that the average SAT score on an unselected sample of high school seniors was considerably lower (maybe 100 points for math + verbal) than the average of students who sign up to take the test.
Therefore a +3SD score among SAT test takers corresponds to a higher Z-score when compared to the entire population of 16- and 17 year-olds.
