I personally feel its a good predictor of your actual level. I think that the knewton tests are slightly tougher than the actual GMAT(personal opinion). I took a course with Knewton and took all their 6 CATs. I started at 680 with the Knewton diagnostic and ended up at 760 in the actual GMAT.
Thanks Guys..TO be honest CR is causing a drop in my scores..Got only 2 incorrect each on RC and SC. But got 6 incorrect in CR. SO a total of 10 incorrect in Verbal with most of them coming in the beginning. Any tips on strategies on how to attack verbal section.
Quant - 8 Incorrect. But i think with GMAT prep that should be a score of 48-49.