I bought the Manhattan GMAT sentence correction guide, which entitled me to the 6 CATs, and so I decided to take one. I had previously done well on the official GMAT prep software, scoring a 710. However, I felt really nervous when taking it and I don’t think it was my best effort. The timed CAT format psyched me out. To get past the nervousness I took the first MGMAT cat with an ‘I don’t care’ attitude, and scored a 720. Does this represent an improvement over the 710, or is the score scaling different?
A 10 point difference is not an improvement or a decline (depending upon which direction you go). The standard deviation of the official test is 30 points, which means any scores within 30 points of each other are not statistically different. The st. dev. of our test is about 50 points. The st. dev. of GMATPrep has not been published but I assume it is a little bit worse than the real test (because the question pool is much narrower), so I think of it as 40 points.
So a 710 and a 720 are really about the same score - there's no statistical difference between the two.
Aside from that, though, nice scores! Those are fantastic scores in general.
