How is GMAT scoring done?

This is a much hyped topic. In fact GMAC, the body that governs this exam hasn’t ever disclose the algorithm used to score the exam. So obviously there are many speculations on the topic. But there are few things that we do know.

GMAT is a computer adaptive test or CAT. This means that the difficulty level of the next question that pops up in your screen depends on whether you marked the previous one right or wrong. If you mark the previous question right then the next question will be harder and if you mark the previous question wrong then the next question will be easier than the one before. The very first question is of average difficulty level. As you proceed with the test the algorithm decides whats your aptitude level and keeps scoring you on that, giving a final score at the end on the basis of how you performed in all the questions.

Illustration:-

GMAT740 gets this question as the first question of the QA section.

1) James takes 1 hour to travel from his school to his college and 2 hours while returning back. What is the average speed of James considering that the distance between his school and college is 15 kms.

a) 10km/hr
b) 7.5km/hr
c) 5 km/hr
d) 7km/hr

Lets assume that the difficulty of this question can be mapped to a 600 score.

Now if I answer this question correct which is option ‘a’ then the next question would be more difficult, lets say of a 620 score level. On the other hand if I answer the question wrong the next question will be easier, lets say of a 580 level.

So if you keep on marking the questions correct your subsequent questions will be more difficult but your score would also increase.

A myth about scoring pattern:-

People have a notion that the first 10-12 questions are more important then the later ones. And that test takers should focus more on the first 10 questions then the last ones. This is completely false. There is nothing like the first few questions are more important. The penalty of marking a question anywhere in the section wrong is the same(though it depends on how you had performed in the previous ones). Ideally one should not try to spend more time in the first few questions just for the sake of getting them right. It might lead to you to miss/guess on some questions in the last. The more you guess the more your score would decrease.

Ok this much for how GMAT scoring is done. For computer geeks who want to taste some more of it search for- Response Theory, the algorithmic theory on which the GMAT is based.

PS: GMAT also throws some experimental questions at you. These wont be counted in calculating your score. They are just there to check what should be the difficulty level of that question.