When preparing for the GMAT (and any other test, for that matter), it's only natural to expect performance improvements as you progress in your studies. However, for many students, score improvements can be erratic or difficult to perceive-despite following a solid study plan! Don't worry-if you fall into this category of GMAT test takers, you should understand that there are two good reasons why this might be happening.

1. Test Scores Are Not Always Comparable

There are plenty of practice tests available on the market. In fact, most prep companies offer at least five with their courses or books. Most of them will even let you take a diagnostic test for free, just to sample their product and decide if it's the right one for you. However, the GMAC (the makers of the GMAT) has not released the algorithm used to determine your score on test day-it's actually a trade secret! This is why most companies do their best in approximating this algorithm, but their best guesses may not always be accurate.

Besides algorithm issues, the structure and feel of problems are not the same among the practice tests in the market. Again, since the problems used in the actual exam are the property of GMAC, prep companies can't use these real questions in their practice tests. Instead they try to mimic the GMAT style of problems, but they are not always successful. 

Thus, different test prep companies interpret the GMAT in different ways in terms of algorithm and questions; this is why comparing your practice test scores among the various company brands is not an apples to apples comparison. You should put every score in context and research the different strengths and weaknesses of various tests on the market. The Beat The GMAT forum is a great place to start this research. One hot tip would be the fact that the tests on the GMATPrep software (freely downloadable on MBA.com) are considered the most reliable because they are released by the GMAC, using real (but retired) questions and the test-day algorithm.

There's another factor you should take into account when comparing test scores: did you take each and every practice test under the same conditions? For instance, taking a CAT (computer-adaptive test) on a Sunday morning is very different from taking the same test on a Wednesday evening, after a hard day at work. Noise levels, personal problems and your biorhythm also affect your concentration.

2. The First Few Scores After Your Initial Diagnostic Tend to be Lower Than Expected

As one of your first steps in preparing for the GMAT, you should take a practice test (preferably one of the two from GMATPrep) to see what's your baseline score and what your general strengths and weaknesses are. However, the scores you receive on CATs in the following two to three weeks might not be that representative of your progress. The simple reason for this is that students tend to acquire the most information in their very first weeks of prep. They will usually accumulate a lot of concepts and theory at a notably fast pace. Actually applying all this new knowledge in a timed environment takes practice, though.

Think about it this way: when taking your second (and possibly third) test, you have a considerable library of information available while you're solving each problem. However, since you haven't had that much time to practice using this library, the books (concepts or specific strategies) are not sorted properly. As you progress and practice under realistic conditions, it becomes much easier to find the book you're looking for, because you're already familiar with it. To put it simply, practice makes perfect.

This is why lower scores on your second or third test do not necessarily mean that you're following a flawed approach. As mentioned above, lower scores on different companies' tests can also be partially explained by flaws in how these practice tests were constructed. However, if you do not find yourself in one of these two scenarios, it's possible that you need to take a step back and reevaluate your study habits and your materials.

The materials that you use are crucial to your success. You'll find a few recommendations in this article about retaking the test. The main idea when trying to find the best resources is to use time-honored classics, such as the Official Guide for GMAT Review series and other books released by major test prep companies. Using an ineffective strategy or practicing with the wrong set of problems will certainly impact your performance.

Your approach to studying is at least as equally important as the materials you select. Consistently low scores might indicate that you have not adopted the correct strategy in dealing with this test. A complete strategy analysis should start from the general outlines of your plan and go right up to your problem solving techniques. This is why your first move would be to evaluate whether you have chosen the appropriate method for study. While some test takers do hit their target scores with self study, others do not fare so well on their own. This has more to do with your style of learning than with anything else. I myself study much more efficiently by attending a lecture than by going through books.

From this macro level of your study plan, you should move on to more specific details that might be preventing you from reaching your peak performance. One of the most common mistakes (and hardest to acknowledge, I would argue) is going too fast through your materials. Think of it this way: you've read and understood all the concepts and have been practicing around 50 or so questions per day. Why aren't your scores increasing? The issue here is the focus on quantity rather than quality. You shouldn't neglect note taking when you're going through concepts and you should spend enough time analyzing why some answers are wrong and some are right. This holds true even if you selected the correct choice! Being able to eliminate trap answers means that you understand this test at a much deeper level.

Stick To Your Plan

Don't expect that your GMAT performance will improve consistently week to week.  It's okay if there are blips or outlier results in either direction.  The most important thing you can do is find a good study plan and stick with it.  Don't over-analyze one poor performance, but certainly do the follow-up work to determine what might have happened.

If you can stick to your plan then you should be able to enjoy fine results on test day!

About the Author: Dana is a finance student and a moderator for the Beat The GMAT - GMAT & MBA Community, one of the world's largest online resources for GMAT prep and MBA admissions advice.