Sometimes the original just can’t be beat. Think of your favorite soda or cereal brand. Now think of the supermarket knock off versions – the RC Colas and Cruncheeos of the world that populate the bottom shelves of your Safeway, Ralphs or Stop&Shop. Maybe it’s an effect of branding, but they just don’t taste as good, right?

The same goes for GMAT practice tests. The original just can’t be beat. By this we mean the practice tests produced by GMAC, the company that makes the actual GMAT. Of course in this case, we’re not talking about taste, we’re talking about score, in particular the adaptive algorithm that powers the GMAT by selecting the difficulty level of the questions you receive on the test and that ultimately generates your score.

While many test-prep brands advertise that the algorithms powering their practice tests mimic the GMAT, these CATs (computer adaptive tests) still fall short of reproducing the test-taking experience of the actual exam, not to mention the score. No company except GMAC can replicate with complete accuracy how the GMAT’s scoring algorithm works. Just ask any tutor worth their salt, and they’ll say the same thing.

Therefore, any serious GMAT study plan should include one of GMAC’s official practice tests. And no, Prep4GMAT isn’t being paid to endorse GMAC material; GMAC practice tests are available free for download from the company’s website. They are the most accurate GMAT practice test, and since the GMAT’s algorithm remains a closely guarded secret, they’re likely to remain so, so that’s why we strongly recommend their use in GMAT prep.

Why does the accuracy of the score matter in a practice test? A practice test is just practice right?

The best and worst part of taking a practice GMAT is that the score you receive doesn’t count for anything official. Poor scores don’t hurt you, but high scores can’t be put on your application no matter how impressive. The true value of a practice test is three-fold: The score you receive predicts how well you’ll do on the actual test, the experience of sitting through a full length test prepares you for what you’ll go through on test day, and your performance on the test helps you figure out what you need to study in order to improve.

Algorithm accuracy, or rather how well the practice test’s algorithm mimics the GMAT’s algorithm, is critical to how well your practice test score matches what you would have received on the actual GMAT. If you want to get a sense of how close you are to your desired score, taking a practice test that doesn’t accurately replicate the GMAT’s algorithm will only give you a ballpark figure of where your score may have fallen. Unfortunately, a ballpark figure is about as close as you can get to predicting your actual GMAT score with third-party practice tests.

What about the practice tests made by other test prep companies?

What other GMAT practice tests lose in score accuracy, they try to make up for in analysis. Most GMAT practice tests offered by the standard test prep brands provide detailed, actionable information on your strengths and weaknesses as well as your pacing. This information helps the third reason for taking a practice test mentioned above: The information about your performance helps you determine what you need to study in order to improve.

Since Prep4GMAT is an app, it constantly tracks your performance, not just on tests but also on practice questions. This way, you don’t have to take a lengthy practice test to see where you stand as the app’s Analytics tool constantly tracks your performance and provides helpful feedback.

How often should I take a GMATPrep practice test?

While the GMATPrep software comes with only two full-length practice tests, the tests’ question banks (the pool of questions the algorithm selects from) are large enough that you can take each test twice without coming across repeat questions. This gives you four full-length practice tests that accurately reproduce the scoring algorithm of the actual exam.

How many tests you take and when you take them is up to you, but the rule of thumb is to take one practice test when you first begin your prep and one a week out from your test date. The purpose of the first test is to let you know where you stand: How close are you to the score you want to receive, and which areas of your performance need improvement. The second test is a trial run for the real thing. It’s not easy to sit and focus for four hours straight, but simulating with practices tests can help you strengthen your focus for test day.

However, do not take a practice test the day before the actual test. If you do, you run a high risk of tiring yourself out for the GMAT when you take it the next day. Also, do not use the GMATPrep practice tests or any practice tests as the basis of your GMAT prep. Practice tests are a poor medium to learn and master the material tested on the GMAT. For this you need practice questions with explanations that you can work through slowly before trying to tackle at pace.