How is GMAT score calculated from section scores?

Question

So I've read a dozen online articles on how GMAT section scores are determined, but I could not find any information on how the section scores are combined to determine the 200-800 GMAT score. If the same score of each section indicates the same level of proficiency in the skill, why would the combination of two identical section scores not result in the same overall score, provided that the two exams are administered at about the same time to eliminate historical trends?

AjiteshArun · Answer

Identical scores do not necessarily imply identical skill levels. Even if we don't consider measurement error, the GMAT actually scores test takers on a  continuous  scale. The total score that you see is from scores that are derived from this continuous scale. The score that test takers see for a particular section is separate from even those scores (the ones used to determine the total score). So the answer to your question is that the sectional scores exposed to test takers are just not as accurate. This is not much of a problem in verbal, because the percentiles there are very close to each other. But it is a problem in quant, where the difference between (let's say) 49 and 50 (or between 50 and 51) is actually quite large.

Just keep in mind that schools are not as worried about this as you might be. They tend to focus on the total score anyway, and if they need to take a look at the sectional scores, they go with the scaled scores.

Congratulations on the 770!

HiLine · Answer

Fascinating information, Ajitesh. So if I read your post correctly, each section has a continuous scale and the overall score also has its own continuous scale, resulting in 3 independent scales? And a 700 score is actually some score in the (705+, 715-) range on the overall continuous scale?

Thanks a lot!

AjiteshArun · Answer

Correct, but the total is not on a continuous scale. The algorithm runs on only two sections (quant and verbal) and that's where the first (and most "accurate") estimates come from (AWA and IR are not adaptive).

HiLine · Answer

Hmm what kind of scale is used for the total score then? I was imagining the scale for the total score was the same kind as those for the sectional scores, only with both Quant and Verbal performance taken into account.

AjiteshArun · Answer

The total is on a discrete scale. If you're wondering why the scales exposed to test takers are less accurate than they can be, the reason is that the GMAC wants to ensure that all GMAT scores are comparable. For example, they would say that a Q49 today and a Q49 from before the GMAT became adaptive(!) indicate the same ability level. That ability level is much more common now, so the only difference would be the associated percentiles.

The bottom line is that even if the workings of the GMAT change, the results produced internally must eventually be mapped onto the  same  external scales that both test takers and schools are familiar with.

HiLine · Answer

Wait so is the total score scale discrete because the pre-CAT total score scale was also discrete? :shock:

I didn't think the sectional scales are less accurate than they can be. I mean, if they are continuous scales, how could they possibly be more accurate?

SamirAbrahao · Answer

If I understood correctly, then the bottom line here is that the total score is not directly derived from the scaled score in each section, right? Thus we could have differing total scores for the same combination of exposed scaled scores for Q and V. Another way to say this is that the Q and V scores are calculated in a different way than the total one.

Why would they want to keep the Q and V scores comparable (BUT NOT THE TOTAL) to the ones from old versions of the test, if the tests are only valid for 5 years?

Why would they want to keep the Q and V scores comparable (BUT NOT THE TOTAL) to the ones from old versions of the test, if the tests are only valid for 5 years?

AjiteshArun · Answer

The sectional scales shown to test takers/schools are less accurate. Think of it as internal (more accurate) being mapped on to external (less accurate). These external scales are the 6-51 & 200-800 scales that everyone is familiar with.

Yes, this is the reason that seemingly similar sectional scores with (slightly) different total scores are sometimes seen. 5 years is not very long from the perspective of the GMAT and the schools that use the GMAT. Changing scales takes time and money. It's like what happened with the GRE. Anyone who took the new GRE in the first few months couldn't apply using their score (and didn't see any associated percentiles). ETS had to spend a lot of time communicating the changes to all the parties involved.

SamirAbrahao · Answer

So the short term hassle involved in changing these scales is greater than the long term impact of the odd relationship between the total and the section scores? Makes sense...

AjiteshArun · Answer

Not as short-term as it might seem. The GMAT would be throwing away a ton of validity studies and research (going back decades) that helps schools use GMAT scores and would have to start again from scratch

	Target Test Prep - Save up to $599 $400 Discount + $99 Bonus GMAT Club Tests
	e-GMAT: 60% Off on GMAT Focus Get to 735+ from any starting point
	Magoosh increases your score, guaranteed - 15% off ALL Magoosh GMAT plans with code GMATCLUB15 + Free GMAT Club Tests.
	Manhattan Prep: $99 Bonus Score Higher on Your GMAT Exam. Guaranteed.
	Experts' Global - ~~$1720~~ $960 End-to-End GMAT Prep + App Support: 150+ Videos, 2000+ Questions, 15 FLTs +
	GMATWhiz - $299 ~~$499~~ Experience the course through a free trial.
	GMAT Club Tests - Free Included with every course purchase of $149+ View all deals

How is GMAT score calculated from section scores?

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards