• A Quantitative Ability score (on a 0–60 scale)
• A Verbal Ability score (on a 0–60 scale)
• A combined Quantitative/Verbal score (on a 200–800 scale)
• An Analytical Writing score (on a 0–6 scale)

On each scale a higher score indicates better performance. Let’s focus on the first three scores, which are based entirely on the two GMAT multiple-choice sections: Quantitative Ability, which contains 37 questions, and Verbal Ability, which contains 41 questions. The 0–60 and the 200–800 scaled scores do not simply reflect the number of questions you answered correctly. These scaled scores also account for the difficulty level of the questions you answered correctly, as well as the extent to which those questions cover disparate question types and skills. It’s a complex calculation, of course.

As for why the testing service employs the 0–60 and the 200–800 scales, rather than other numerical ranges, there’s no compelling reason. The ranges are arbitrary and were established many years ago. The testing service continues to use these scales so that older scores can be compared directly with more recent ones.

Your fourth scaled score—for Analytical Writing—is the easiest to understand. There’s no conversion or complex calculation; the score is based on the overall quality of your writing and your reasoning, as determined by two GMAT readers, who follow general scoring guidelines established by the testing service.

Percentile rankings are solely for your information—to help you assess your relative performance. They aren’t reported to the B-schools. Even if they were, the schools would ignore them, because each B-school is interested in ranking you among only its applicants, not among all GMAT test-takers.

Once you’re past the first cut, the school will take a closer look at your GMAT Analytical Writing score. If you’ve scored very high in GMAT Analytical Writing—perhaps 5 or 6—the admissions committee might rank you higher among its remaining applicants despite a relatively low GMAT Verbal score. (This is where the individual Verbal score can become a factor in the admissions process.) In reality, though, applicants with lower GMAT Verbal scores typically score poorly on the Analytical Writing as well. What’s more, in this case an outstanding personal statement would not accomplish much toward redeeming your application, because too many applicants obtain help in writing their personal statements. In other words, the personal statement is not a reliable indicator of your writing ability, or you verbal skills generally.

Another factor contributing to the trend toward higher GMAT scores is that, since the introduction of the computer-adaptive GMAT in October of 1997, test-takers can take the GMAT any month of the year, as many as a dozen times a year, rather than only four times per year—as was the case when the GMAT was offered as a paper-based test. Repeat test-takers tend to score higher than first-time test-takers, and with year-round availability of the GMAT there are more repeat test-takers.

The trend toward higher GMAT scores will begin to level off somewhat, and probably already has, because the year-round computerized GMAT has been available for about three years now and because percentile rankings are based on data from only the most recent three years. So we’re at the end of a transitional period where people who took the test prior to the availability of the CAT (Computer-Adaptive Test) might very well score lower—at least in terms of percentile ranking—were they to retake the GMAT now.

I’m sure the testing service is aware of this trend, but there’s nothing the service can or should do about it. After all, why penalize applicants today for studying harder for the GMAT, or simply for having an opportunity to take the test more often?

Each B-school establishes its own policy for processing multiple GMAT scores. The most common policy is to average multiple scores. (Quantitative, Verbal, Combined Q/V, and Writing scores are each averaged separately.) A minority of schools will disregard all but your highest scores. (Again, Quantitative, Verbal, Combined Q/V, and Writing scores are each considered separately.) A few schools have adopted a hybrid approach, whereby they average scores from multiple tests unless there is a large enough discrepancy between scores—in which case they look only at your highest score. In any event, most B-schools disregard GMAT scores that are more than five years old.

The chief consideration in deciding whether to repeat the GMAT is that approximately 90% of test-takers improve their combined Quantitative-Verbal score by repeating the test. So the statistics weigh in on the side of repeating the test. I don’t mean to suggest, however, that every GMAT test-taker should repeat the test. Other factors should influence your decision as well. Perhaps you prepared diligently for the exam, during which your concentration and your pace were both good, you felt alert and clear in your thinking, and you had time to consider all 78 multiple-choice questions without panicking or rushing. If so, think twice about repeating the exam; you run a real risk of sabotaging yourself by performing worse the next time around—especially if you’re applying to schools that average multiple GMAT scores.

Many test-takers hold unrealistic expectations in terms of their GMAT scores. It’s understandable that you might want to gain admission to a top-tier B-school, which will require very high GMAT scores. But don’t base your decision about whether to repeat the test on the admission standards of your first-choice school. Instead, focus on whether you performed as well as you can realistically expect, given your innate cognitive abilities and your English-language skills.

This advice assumes, of course, that your practice tests actually simulate the style and difficulty level of the real GMAT. Much of the internet discussion on the various GMAT message boards centers around this issue—specifically, what books and software do the best job at simulating the real test. I’m not at liberty here to recommend certain products over others. But I will say that I’ve seen a lot of substandard material in GMAT books published by so-called "reputable" publishers. And the quick-and-dirty approach to creating practice questions is especially pervasive on the Web—where I’ve seen some absolutely atrocious content, especially at the test-prep sites of upstart dot.com companies. Stick with the Web sites of publishers who are well established in test-prep print publishing, and with authors such as myself whose practice questions have appeared in many such books for many years.

Taking full-length practice tests will help you identify your weak areas. But to improve in those areas you should focus on building skills rather than rote practice. Most general bookstores stock a variety of workbooks targeted at specific areas of the GMAT. I’ve written several such books myself—for math, reading comprehension, and the GMAT essays.

Besides, placing undue emphasis on practice-test scores can easily result in performance anxiety, which can be counterproductive. Instead of obsessing about scores, you should focus on what you can realistically do before exam day to improve the skills needed to better those scores.

Another idea is to look carefully at the admissions criteria of the schools you’re interested in, to see which ones focus less on the numerical data (particularly GMAT scores) and instead take a holistic approach toward the admissions decision. There’s a strong trend in this direction anyway, as schools are beginning to acknowledge that other intelligences, such as leadership and other interpersonal skills, have just as much bearing on success after B-school as your performance on one half-day standardized exam.