Your link doesn't offer any sort of evidence against Gladwell's contention (which isn't original to Gladwell, and which on the basis of negligible evidence I su

Your link doesn't offer any sort of evidence against Gladwell's contention (which isn't original to Gladwell, and which on the basis of negligible evidence I suspect is an oversimplification but not far from the truth). In fact, arguably it offers a little evidence against what Gladwell says. If IQ above ~120 makes no difference to performance, and if "career" and "performance" are close enough to make it worth while citing this thing at all, then you ought to see no little difference between {occupations substantially found among people with IQ ~120} and {occuptations substantially found among people with IQ ~130}. Now, look down the 120 and 130 lines of that plot, and notice that you see quite different things in the two instances. (The foregoing is a bit of a simplification, but it'll do. Anyway, I see no way to read the graph as providing evidence that IQ 120 is better than IQ 110, but IQ 130 isn't better than IQ 120, in terms of likely success/performance.)