Well, percentile rankings tell you something: that is to say, what percentage of test takers did worse than you. If you get a 50 in quant, then I believe it's something like 94% or 93% - that means you did better than 94% or 93% of test takers.

The percentiles do vary in time. For instance, 750 used to be 99%, but now it's not, I think it's something like 97%.

Thanks DanaJ. My question is more like this: you and I both take the GMAT yesterday and we both get 50Q. I figure it is possible that you did slightly better than I did (i.e. you got one fewer question wrong, or something else with the result that we have the same raw score but if percentiles were infinitely granular, you would have done better on a percentile basis). Will we ALWAYS see the same percentile, whatever it is? So let's say 93%. EVERYBODY who gets a 50Q yesterday sees the same percentile, even though I would think some may have done better than others? Or maybe would you see a 94% and I see a 93%?

The answer is: you and I will always see the same percentile ranking. This might fluctuate over large periods of time (i.e. in months or years), but not if we take the test in the same day/in the same month.

Thanks so much!