...the 94th percentile on the GRE isn't the same as the 94th percentile in the general population or even as compared to undergrad students b/c it is a select group that takes the GRE. That group is, presumably, well above average in terms of achievement at least in that they are planning to obtain at least a Masters degree. Being in the top 6% or higher amongst that group is likely indicative of pretty high achievement.
But the point of the test isn't to measure achievement in comparison to the general population. The GRE is supposed to measure achievement among people who are high achievers already: people who did well enough in college to continue on to grad school.
The math section has nothing harder than basic high school geometry: there are no questions about statistics, no trigonometry, and no calculus. Most of the questions are straightforward, with only a few slightly tricky ones.
My feeling is that the GRE fails as a measure of talent or achievement among people who are supposed to be talented high-achievers. It measures averageness. And the quantitative section measures this on junior high and high school math, no less. Verbal is not much better, and the subject tests don't discriminate well either.
If you look at the average scores of people who major in education... well, the numbers are pretty depressing. The results are saying that people who want to become teachers can't do basic algebra and geometry questions, after supposedly having studied these subjects for this test.
Overall, I don't think the scores reported by ETS say much that's good about the aptitude and/or study habits of the majority of test-takers. Plus, even if the super-smart super-high-achievers can only score inside 2 or 3 SDs of the mean, what does that say about the level of cynicism among the people who wrote the test?
