Kaplan's Diagnostic-- accurate or not?

Fellow Kaplan (or Princeton Review) Students: how close was your score on Kaplan's diagnostic test (the 1/2 length test you took on the first day of class)to your real MCAT score. I've actually taken it twice-- first time, 10V 8P 7B, second time, 10v 7P 9B.

Is the diagnostic score scaled against all the other people who took the diagnostic, or is the scoring "tuned" to accurately represent what you might score on the real MCAT against people who have studied and are taking it for real? Here's to hoping it's the latter... Thanks.