JOHN MAYNARD KEYNES (pictured) described inflation as an illusion of wealth. In other words, we tend to think of our assets in their absolute terms, not in terms of what they can buy. What would Keynes have made of GMAT scores? At the turn of the millennium, the average GMAT score at an MBA programme ranked in The Economist's top ten was 688. In 2014 it was 727. Admittedly, the Indian Institute of Management, a newcomer on the GMAT list is an anomoly—it has by some margin the highest numberof applicants per places of any school on our ranking, so can choose only those studsents with the very highest GMAT scores. However, at more familiar schools such as Stanford, Harvard and Chicago average scores have been rising for years.

So are MBA students getting brighter? It is unlikely. More probable is that compeition is getting fiercer. Schools often claim not to require a minimum GMAT score from applicants. But the reality is different. Every year a handful of high-calibre students might be admitted with sub-standard scores, but they are exceptional in both senses of the world. There will be some aspect of their working or personal lives that truly sets them apart. For the rest, keeping up with rising expectations means ever more GMAT preparation. One hundred hours of groundwork before sitting the test is now common. Companies offering tutorials (including The Economist) ensure that the applicant arms race continues unabated.

Another factor is the competition between schools themselves. One reason they have become more likely to select students on the basis of their GMAT scores, before thinking about their other attributes, is that it affects their ranking. (By making GMAT such an important part of its assessment, The Economist must take its fair share of the rap for this too.)

All in all, as Keynes would point out, a score of 727 buys you no more today than a score of 688 would have 14 years ago. But having said that, GMAT is a useful indicator of likely success on a course. Students will struggle without the quantitative skills it measures. And while foreign students may grumble that they are at a disadvantage with the verbal reasoning and writing aspects of the test, the fact is that most top MBAs are taught in English, and students without sufficient language skills will be at a disadvantage here too. In this sense, the GMAT is a necessary inconvenience.