score select - how will this affect percentiles?

[iowaguy]

OK, I've been pondering this new ETS "score select" option and how it might affect percentile rankings for a given score. My hypothesis is that now folks will tend to take the test more often (since they don't have anything to lose besides time/money) than before (when every score was reported).

One line of logic would be that maybe test takers aren't as prepared for their first GRE test since they don't have to report it, and might be planning a 2nd or 3rd test already. This would tend to increase the percentile rank of a particular score (say V163).

Another line of logic would be that only people who can really afford to take a lot of tests @ $175 a pop + the score select fees will be the ones who will be taking multiple tests. And these folks might be the ones who are the best prepared, most serious, and have the most resources to throw at test preparation. This would tend to decrease the percentile rank of a particular score.

The kicker is, the percentile rank only represents the number of tests taken, not the number of students who took the test (I think this is correct?) i.e. for a particular score (V163), it might rank in the 90% percentile of tests taken (10% of tests achieved this high of a score), but might actually rank in the 95% for students (i.e. perhaps only 5% of students achieved this high of a score, factoring in the multiple tests that top students take).

Thoughts?

Edited August 29, 2012 by iowaguy