Over the past several months we’ve had more and more students note a disconnect between their scores on the NBME practice tests and their final USMLE Step 1 score, and they are voicing their unhappiness on forums like Reddit and Student Doctor Network.

As of March 2021, there are six NBME CBSSA forms currently available for purchase on the NBME exam portal: Forms  25, 26, 27, 28, 29 and 30.

A quick web search will lead you to numerous posts of individual students correlating their NBME and UWorld Self-Assessment Exam scores with their final Step 1 score.

Bottom line, though:

Looking at medical students as a group, do the NBMEs under-predict, over-predict, or accurately predict scores on the USMLE?

In my personal experience as a tutor, I have found that the predictive quality of NBMEs is very student-dependent. Some students outperform their NBME scores, others underperform. We’ve gotten this question from hundreds of students over the years. There have even been dedicated research studies examining this correlation more closely.

There are several possible explanations for the differences in NBME/USMLE score predictions. First off, stress levels are very high on test day. Test day is different from all your other study days. The anxiety is at an all time high. Adrenaline is running through your veins like crazy. You barely get any sleep the night before. You are so nervous that you can barely eat breakfast. And, if you’re anything like me, you might even have stress-induced GERD leading up to test day. Furthermore, you have the added stress of needing to transport yourself to a testing center. The Prometric staff that day may be nice or they may be rude. Nowadays you even have the added inconvenience of having to wear a mask during your exam. All of these factors influence each person differently. Some people function better under this kind of stress. Others get overwhelmed and may underperform.

Additionally, timing may be slightly different for a given individual on test day. When you take an NBME practice test at home, you may not be strict with your timing. Perhaps you start your practice test at 10:00 AM when your actual exam is scheduled for 8:00 AM. Maybe you end up taking a longer break than time would normally permit on test day.

NBME exams are only 4 blocks long while the actual exam consists of 7 blocks. If you don’t appropriately time and train yourself to be able to get through 7 blocks, your score can suffer on test day. It is important to be able to mentally push through 280 questions on test day and combat any test-day fatigue. This includes packing an adequate amount of healthy snacks, water, and a substantial lunch to get you through that long day. Here’s a handy list of everything you need (and don’t need) to get through test day.

Bottom line? When taking your NBMEs, try your best to simulate the actual testing environment: minimize distractions, utilize Timed mode, commit to completing all of the question blocks in one sitting, and yes–take the exam while wearing a mask. In this way, you will help the practice assessments work for you, by providing a ballpark score range that will be closest to your actual score.

Keep in mind, though: practice tests are meant to be used as a learning tool to assess your strengths and weaknesses both in terms of knowledge content and test-taking habits as well as simulating exam conditions. They should be incorporated into every student’s study schedule.