By universal consensus the most feared and loathed element ofthe whole MBA experience happens before a student even gets to a business school. It is the Graduate Management Admission Test, or the GMAT.

About 900 top business schools require applicants to sit (or in MBA parlance "write") the GMAT before even considering them. An acceptable score on this computerised multiple-choice and essay exam is a prerequisite for entry to most MBA programmes.

The GMAT is sponsored and directed by the Graduate Management Admissions Council (GMAC), an international organisation of 131 graduate schools of business which, as well as the GMAT, offers a number of services to business schools and prospective students. The test, which is administered on GMAC's behalf by Educational Testing Service in Princeton, New Jersey, measures language, quantitative and writing skills and is designed to help predict a student's potential academic performance on an MBA programme.

Schools usually look for GMAT scores of about 550-650. The maximum achievable is 800, though in any given year only about 50 candidates score this. Although no schools will admit this publicly, 600 is widely regarded as the cut-off point for admission, at least in North America. The only chance for students with a lower mark is the unlikely event that a leading school fails to fill its quota of students. Even then, they will comb through academic records back to kindergarten to justify admitting students.

Although universally accepted, the GMAT is peculiarly American in tone and sits alongside other standardised tests that are common for entry into US graduate schools. These included the generalist Graduate Record Examination, the Law School Admission Test and the Medical College Admission Test.

James Dean, associate dean and director of the MBA programme at Kenan-Flagler business school in North Carolina, says: "We are evaluating students from all over the world and lots of different educational systems. We need something to calibrate across them. The GMAT at least puts them on the same level."

As with all intelligence tests, exactly what the GMAT measures is open to doubt and some controversy. Questions surround its use as an initial screening mechanism (something few schools admit to) and, linked to that, its alleged cultural bias, that favours, it is said, North American students.

Carlos Cavalle, dean of Iese in Barcelona and chair of the GMAC board, believes that work to improve the GMAT's cultural relevance must continue. But he points out that GMAC itself plays a much wider role in acting as athink-tank for business schools on the changing needs of business.

Ian Rudy, director of admissions at the Judge Institute of Management Studies at Cambridge University, says his school does not set a minimum hurdle. "That would be unfair," he says. "We have a very international body of applicants and you simply cannot compare the scores of people from the US and UK and those from, say, Asia or Latin America, especially on the verbal component."

However, Sherry Wallace, director of MBA admissions at Kenan-Flagler, comments: "I have to say that if we had two candidates where all of the other things were equal we would probably give the nod to the one with the higher GMAT score."

According to Paul Danos, dean of the Tuck School at Dartmouth College in New Hampshire and a member of the board of GMAC, some schools undoubtedly use the GMAT as a screen.

"What do you do if you have 10,000 applications - read them all?" he asks. But, he adds, no one uses the GMAT on its own.

Perhaps the greatest concerns about the GMAT are its supposed cultural bias.

"Is it culturally biased? Without a doubt," says Mr Rudy at Judge. "It is not just the verbal element, it is the whole set-up of the test. US students are used to standardised tests. Elsewhere, there might be more emphasis on long essay-type exams and assessment of coursework. So people are not used to this bang, bang approach."

Prof Danos is not impressed by such arguments. "Every test is culturally biased," he says. "GMAC tries very hard to work on that but it is a tricky thing to fix. Schools take the bias into consideration. Language is obviously a problem, but if you want to do an MBA programme in English then you have to do the GMAT."

Peggy Liu, a student at Judge, with English as a second language, says she believes native speakers of American English do have an advantage. "The maths is not too difficult, with a bit of practice at least," she says. "So the psychological and actual benefits of handling the verbal sections with relative ease tend to propel the scores of American test-takers."

All of which may go some way to explain why the GMAT is so roundly disliked by students.

"Most prospective students view the test as a game they must master to achieve a minimum acceptable score for top MBA programmes. It seems to measure test-taking ability rather than business acumen," says Mr Ryan.

But Ms Wallace, of Kenan-Flagler, has a more down-to-earth answer: "Students don't like the GMAT because they can't control it," she says. "They can work hard for grades, get good references and so on but to some extent the GMAT is still a lottery."

On the other hand, Joanna Malinowska, a Polish student in her second year at Kenan-Flagler, says: "I never felt bad that I had to take the GMAT. I treated it as a reasonable condition to get admitted to the school of my choice. There must be a benchmark allowing schools to compare candidates from different cultural backgrounds. If GMAT did not exist, something very similar would be created - maybe on the international scale. That could potentially allow for a higher degree of fairness."

And that seems to be the point - the GMAT is an unavoidable evil. If it didn't exist it would just have to be invented.

In the next article, George Bickerstaffe will prepare for and sit the GMAT