GMAT official vs mock score algorithm

Question

Something is quite confusing with the GMATs scoring algorithm, is a score like this in quant 43rd percentile? (Q77), 5 scattered mistakes that aren't even in the beginning, whereas during my official mocks id get 8-9 mistakes yet be in the 60-65th percentile, can any GMAT expert help me understand how the grading works? I doubt I can make less than 5 mistakes if i retake the GMAT.

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bb · Answer

Hi. The 2 algorithms are supposed to be quite close with only operational differences.

However, there are differences with the question banks (what questions you get to see) and also stress. In general the algorithm is pretty standard - we even built it for the GMAT Club tests - it is quite complex but standard and it works fairly predictably too but the part that you won't know and won't be able to figure out is what question parameters were responsible for your score. you need to know difficulty of the question, its discrimination parameter, and its guessing parameter - we wont' find those out unfortunately for your real test or for the GMAT prep even.

The test builds a picture of you (and your score) and it is a confidence interval that then becomes a score and the test has to reconcile mistakes on easy questions and correct hard questions to figure out which score to give you. These two are conflicting.

Ultimately it is not the number of mistakes but the ability to consistently answer easy and medium questions (don't worry about hard) that gets you higher scores becuause if you have a solid base and even with a few hard ones correct the algorithm is more certain about your ability.

Archit3110 · Answer

try to avoid making any mistake especially in quant, the algorithm is definately not very straightforward its complex and its of no point decoding it beyond certain limit... prepare well give as many mocks as possible... all the best

gmataccount123 · Answer

If a few mistakes happen in a row, the algorithm may rapidly downgrade the difficulty of your subsequent questions, capping your maximum possible score for that section

AllisonBell · Answer

A couple things to note here:

On the GMAT,  where you end is what you get.  In addition, your  score is primarily impacted by the mix of difficulty of the questions you see.  Because of that, missing questions towards the end of a section is actually more impactful than if the misses are scattered throughout or even primarily at the beginning. The reason is that each time you miss a question, the GMAT lowers the difficulty of the next question. Since you missed three questions in a row toward the end of the section, there was no time for you to dig out of that hole. 
  Missing easier questions is worse for your score than missing hard ones.  So your score could be lower than you expected if the questions you missed on the official exam were lower difficulty than on your mocks. The reason for this, again, is because missing an easy question pulls down the difficulty of the next question, making it harder to achieve a high difficulty mix.

A side note: You invested a lot of time on a few early questions. Those questions aren’t worth more, and they don’t impact your score more. Having a balanced timing strategy is the best way to optimize your GMAT score, and that means not going over 3.5 minutes on any one question (if you have standard time). Some timing adjustments earlier in the section may have given you more time for the three late questions you missed, boosting your score overall.

For more on effective GMAT time management, check out this article:  Everything You Need to Know About GMAT Time Management .

GMAT official vs mock score algorithm

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