The standard deviation on our tests is about 50 points, compared with about 30 points on the official test. They don't score consistently high or low - some people score higher on the real thing and some people score lower. If you're struggling with your timing, however, then you will likely find our test extra challenging, as it both mimics the algorithm of the real test and uses a large database of questions. (Most other practice tests don't mimic the real algorithm and the one that uses the real algorithm - GMATPrep - uses a much smaller database of questions, which can have the effect of making the test feel easier at the higher end.)
Anecdotally, my students tend to tell me that they think our math feels harder than the real test and that our verbal feels about the same. (This makes sense to me - we don't build experimental questions into the test, as the real test does. So on our test, you don't get "freebie" math questions that are much easier than your level b/c the test isn't testing experimental questions on you.)
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Stacey Koprince
GMAT Instructor
Director of Online Community
Manhattan GMAT
Contributor to Beat The GMAT!
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