Wow, I was going to write an article about this. Like @Psychodementia , I too have serious doubts about the veracity of this report. I have tried to connect the dots here based on my experience of how schools and QS-like companies function and am pretty sure of the following points,
1. The impressive average IIM GMAT scores in the QS report actually belong to the handful of NRI students who entered the two-year PGP through the GMAT route. Since they have to match up to the CAT benchmarks of 99+ percentiles, it is quite likely that both IIMA and IIMB only consider the very highest GMAT scorers only.
If you read the following link,
"The survey also states that the average GMAT score of students enrolled in the Post- Graduate Programme in Management at IIMB is 780, which is the highest in the entire region 창€“ testimony to the talent and caliber of students at IIMB "
It appears that they have gotten this piece of data about IIMB's 2-year PGPM once and have been dubiously reusing it as per convenience for any mention of IIMB in their surveys. The QS survey does not explicitly mention which course they are talking about, and it is realistically impossible for EPGP to select an entire class with such high GMAT scores who also excel on their essays and recommendation requirements.
Additionally, IIMB's own claim that a handful minority of NRI students give it the boasting rights of having the highest average GMAT in the region is highly questionable and shows intellectual dishonesty on the institute's part. I won't even begin to describe how unrelated "talent" and high test scores are, "caliber" maybe.
Coming back to QS, I think this is a case of a British company mixing up numbers about another country's b-schools --- whose education system they don't understand very well --- in order to make their research report look newsworthy to the press of various nationalities. More on this later.
2. If the above assumption is correct, then it is totally retarded of QS to compare the average GMAT scores of 800+ HBS/INSEAD students and 390 Stanford students with some 10-20 NRI-quota students at the IIMs and draw such conclusions.
3. Please understand, that b-schools the world over routinely REJECT applicants with exceptionally high GMAT scores because unlike Indian b-schools, they don't consider aptitude tests to be the dominant indicator of leadership ability.
Just because Indian b-schools follow the questionable practice of shortlisting the top X candidates from a descending order list of test scores and international schools do not, does not make Indian MBA students any particularly academically distinguished. You can see the average GPAs of the class at HBS/Stanford/INSEAD and they are usually in the range of 3.5+/4 from top US universities, which makes their classes as academically distinguished as education can allow.
All top schools of the world get applications from exceptionally high GMAT applicants. It's just that the top schools don't take the GMAT too seriously beyond a point.
4. QS as a company makes its money by getting b-schools to pay for expensive stalls at its education fairs across the world. Now b-schools wouldn't pay them the money if QS fails to muster large number of student footfalls at its fairs. So it uses all these research reports merely as a marketing tool for QS to remain in the news and create a brand familiarity about it among students in various countries. QS is not a research agency.
In this case, the QS PR managers might have decided to play up the Indian GMAT scores aspect in order to convince local journalists to cover their survey. Just that in the process of playing it up, they might not have cared too much about the veracity of the data.
As for Indian media, we all know how they will lap up any press release that makes for front page headlines, without applying their brains.