Does CAT randomness in difficulty assignment adversely affect scores? : General GMAT Questions and Strategies

Hi gmatretest.

Probably what has happened is that you have been scoring high on the Princeton practice tests and thereby used up most of the hardest questions in the question bank. So there aren't any more to give you.

Obviously the real GMAT is not going to run out of hard questions. So you will not experience similar issues when taking the real test.

Dear gmatretest,
I'm happy to respond. :-)

I think MartyMurray already address one very important issue. A few more things to keep in mind.

1) The CAT procedure designed by the folks at GMAC is their own secret proprietary knowledge. Any GMAT CAT systems offered by a private company is that company's best guess on how GMAC designs their CAT.

2) Truly brilliant folks who are world's experts in psychometrics work at GMAC, and they are the ones who oversee the GMAT CAT. I don't think many private companies have comparable expertise. I have tremendous respect for the brilliant folks at MGMAT and their CATs, but I wouldn't trust many other companies to have CATs that are particularly like the GMAT CAT.

3) I will say that one thing I find laughable are the "difficulty" levels listed in your charts. Difficulty levels listed on some arbitrary scale from 1 to 10 or something like this? Really? In most serious psychometric research, difficulty levels are expressed a decimal percents: in other words, a difficulty of 0.43 means that 43% of test takers in the pool get those questions correct. The fact that difficulties are expressed in terms of a kiddie scale here causes me to question what their other psychometric assumptions might have been in designing this CAT.

MartyMurray is right. GMAC has a question pool that is truly enormous. You could take 12 GMATs and never see a single repeated question. Running out of questions is not a problem.

Here's an article that discusses the GMAT CAT a little further:
What is the GMAT CAT (Computer Adaptive Test)?

Does all this make sense?
Mike :-)

Hi gmathopeful90,

The scoring algorithm on the Official GMAT is far more complicated than most people realize. Since that algorithm is proprietary, no GMAT company has an exact match for it, thus CAT scores can vary a bit based on the 'biases' involved in their respective designs. As such, you really shouldn't be spending your time trying to figure all of that out. A far more useful gauge would be to review each CAT and determine how many questions you SHOULD have gotten correct, but didn't (due to a silly/little mistake). Those mistakes are the things that you have to fix to score at a higher level.

There's clearly a bigger-picture issue here, but you haven't defined what you're *really* interested in; all of this ties into Test Day though, so we should probably start there:

1) How have you scored on each of your practice CATs (including the Quant and Verbal Scaled Scores for each)?
2) What is your goal score?
3) When are you planning to take the GMAT?

GMAT assassins aren't born, they're made,
Rich

Does CAT randomness in difficulty assignment adversely affect scores?

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