Should You Take a GMAT Diagnostic Test?

If you sign up for a test-prep course, it's typical that one of the first things you'll do is take a diagnostic test. Some are more realistic than others. In part, the goal is to determine the level at which you begin studying. Also, it's useful to get an overview early on of what's on the test.

For a variety of reasons, I don't think starting your study plan with a diagnostic test is important. I don't feel all that strongly about this: Taking a diagnostic exam isn't going to torpedo your preparation efforts. But if you're just getting underway and you haven't decided whether to take one, here are some thoughts.

What does it measure?

Most diagnostic tests, whether they are full-length exams or shorter quizzes, are designed to give you a numerical score. When you finish, it might tell you that, today, you would've gotten a 570 on the GMAT. So what?

Aside from the limitations of practice tests in general, that number means very little as a representation of your ability level or of your eventual likely score. Let's say you score a 520 and your goal is a 680. Obviously you have a lot of work to do, but are you 160 points away in terms of content knowledge? Speed? Familiarity with the exam?

For most people, it's some combination of the three. Depending on their math background, analytical skills, and overall comfort with standardized tests, a dedicated study effort might improve their diagnostic score 150 points...or 40. Taking a practice test isn't going to tell you your range on test day, unless test day is tomorrow.

What have you got to lose?

As with any practice test, there's a distinct possibility you'll be disappointed. You probably have a number in your head representing your desired score. If you're just starting to study, you probably won't come close to that score.

The diagnostic score probably wouldn't faze you if it were 60 points below your target. But what about 120? 200? More? Again, no diagnostic test is going to tell you very much about how you'll do on test day, but if you're shooting for a 620 and you score a 420 today, will you have the same motivation to study that you do right now?

Alternatives to diagnostic tests

I'm a strong advocate of making a plan and jumping right in. You probably have a general idea of where you'll need to focus. (Are you doing math for the first time in 10 years? Is grammar a concern because English is not your native language?)

That said, there is something to be gained by (only) getting an overview of the material and question types on the test. My "alternative" to a diagnostic test is...well, a diagnostic test.

The first section in the Official Guide is called a diagnostic. I recommend that my students work through the problems in the diagnostic to familiarize themselves with what they'll find on the test. There's no need to time yourself (though it is helpful to keep track of how long you're taking, as you should do any time you do practice problems), and you shouldn't put any stock in the number that the test spits out.

More than any other diagnostic I've seen, the Official Guide diagnostic gives you a wide range of math and verbal content that you are likely to see on the test. If you think you'll have an easy time with GMAT math, you'll be able to confirm or question that belief.

As always, realistic material is the key. When you're looking at the Official Guide, you're working with questions written by the authors of the test. Whether you're using it to measure your skill level or just to practice, you are making good use of your time in an initial GMAT preparation effort.

About the author: Jeff Sackmann has written many GMAT preparation books, including the popular Total GMAT Math, Total GMAT Verbal, and GMAT 111. He has also created explanations for problems in The Official Guide, as well as 1,800 practice GMAT math questions.

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