Is the GMAT Prep on mba.com accurate?

[cmorris]

I just took the GMAT prep on mba.com and scored 550 (12 incorrect quantitative and 14 incorrect verbal). I scored 600 a couple of weeks ago and answered 12 quantitative questions incorrectly and 13 verbal. I don't understand how my score has decreased so much. I have also been scoring between 600 and 640 (my last 3 exams were 600, 610 and 640) on the ManhattanGMAT CAT exams. Now, I am not sure where I fall in the score since all my scores are so different from each other. My goal was to score 650+, but now I am not sure I can accomplish that after seeing my low score on the mba.com GMATPrep (which is supposed to be somewhat accurate).

Thank you!

[StaceyKoprince]

People answer about the same number of questions correctly / incorrectly at scores anywhere between about 450 and 700. The test isn't scored based upon # correct. :)

The 600 to 640 scores are very similar (the standard deviation on our test is about 50 points; the standard deviation on the official test is about 30 points). The 550 is a bit of a drop (not a huge drop, but somewhat concerning), so the key thing now is to figure out why your score dropped.

Take a look at this article to help you figure that out. If you want to discuss any aspects of the analysis described in the article, do the analysis, then come back and tell us what you found. We'll help you figure out how to interpret it and what to do!

http://www.beatthegmat.com/a/2009/10/26/my-score-dropped-figuring-out-what-went-wrong