I guess I was asking if we can even statistically interpret a 160 on these tests (compared to, say, a 150) or if we just have to wave our hands and say 'it's way out there'.
It seems more straightforward to me with achievement tests for children, since you can measure whether the child has attained certain skills, and then compare that to a normal age of attainment. Then again, that's old-style ratio thinking-- really the way it goes is that a child's attainment is compared for rarity against age and/or grade peers.
From that perspective, as long as you can construct a question where some people get it right and others don't, it's of a general type previously deemed to measure IQ, and the results don't seem backwards-oriented to the other measurements, it's a question you can use for differentiating IQ. A 160-scoring person is just rarer by virtue of getting X more questions correct than a 150-scoring person. That part seems pretty straightforward to me-- what's not obvious is how well IQ tests really measure all of what I consider to be intelligence.
Empirically speaking, though, since they are correlated strongly with certain measures of success, they are measuring something useful. I've seen quotes here recently about physics Ph.Ds generally having IQ scores of 145+, with Nobel laureates etc. higher still, so there must be something to it.
