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The New NBME Step 1 Practice Tests: What You Need To Know

Updated: Apr 7, 2019



A major change to the most important resource available to prepare for the USMLE Step 1 is here. The change involves the available forms of the CBSSAs (Comprehensive Basic Science Self Assessments) published by the National Board of Medical Examiners (NBME), the organization that administers the USMLE. These 5-hour, 200 question practice exams are a crucial part of most students’ preparation for the USMLE Step 1, and are also a key tool for evaluating a student’s preparedness for Step 1.


I often receive feedback from students who feel that the CBSSA questions were reflective of both the content and editorial voice of actual Step 1 examinations, and accordingly, these students are so thankful that they have studied these official practice tests closely. Many students report that having completed and thoroughly reviewed all of these self assessments was a key determinant of their test day success.


The logistics of the recent release of the new CBSSA forms are somewhat complicated. For several years, there were six NBME CBSSA forms available: forms 13, 15, 16, 17, 18 and 19. On March 25th, 2019, the NBME retired five of these six exams and published 3 new practice tests: forms 20, 21, and 22. Form 19, which has been notorious for its harsh curve, was retired, while form 18 remains available. Students who had previously purchased any of the recently retired forms prior to March 25th, 2019 now have 90 days from the date of purchase to complete these forms.


At some point in late Spring 2019, per the NBME, forms 23 and 24 will also be released. Students should note that test vouchers purchased for forms 13, 15, 16, 17, or 19 that are not redeemed within 90 days of the date of purchase will only be redeemable for one of the new forms. The NBME has also announced that the feedback provided by the exams will unfortunately not change (i.e., will not improve) with the release of these forms. This means that only the correct answer choices will be highlighted, without any answer explanations provided.


These actions by the NBME are a significant departure from past precedent in which they have routinely retired a single CBSSA form at a time and replaced it with another form. This is the first time in recent years that the NBME has retired so many forms simultaneously. I typically recommend that students complete 4 CBSSA exams at a minimum, and in circumstances where a student’s schedule and study plan permit, I most often advise completing all available forms. In my experience, tracking down long-retired forms provides little additional value.


One of the hallmarks of effective Step 1 preparation is a well thought-out study plan, a core element of which is careful consideration of how and when to take the currently available CBSSAs. When constructing schedules for my students, I weigh several highly individual factors when ultimately recommending the timing and number of CBSSA exams to take. Regardless of how many CBSSAs are taken and when they’re completed, however, I strongly recommend taking the assessments under the most test-like conditions possible, carefully reviewing each question the next day, and making Anki cards based on all incorrectly answered questions.


Because we find the CBSSAs to be such valuable resources, it’s important to consider the implications of this change for students planning to take Step 1 between March 25th, 2019 and June 25th, 2019. If you might be testing within this window, the potential exists to take some combination of both the newly released and the recently retired CBSSA forms. The NBME hasn’t currently announced any major upcoming changes to Step 1, so the current CBSSA forms will likely remain both relevant and beneficial for students to complete, for those who have already purchased them.


If you’re testing between March 25th, 2019 and June 25th, 2019, then you may have the opportunity to take up to 11 CBSSA forms. While this may be more exams than some students can reasonably expect to work through (either in terms of time, energy, or necessity for a given score goal), for others, it may represent a golden opportunity: 2200 ultra high-yield questions that can help set them up for success on test day. For students with flexible testing schedules currently planning to test before or after this window, it may be appropriate to adjust your current test date to take advantage of the availability of these new CBSSAs.


In an earlier post, one of my colleagues discussed in detail how best to utilize the CBSSAs. As for forms 13, 15, 16, 17 and 19, reviewing every question on the new CBSSA forms will continue to be of pivotal importance to mastering the material covered on the USMLE Step 1. While in the past students preparing for Step 1 on their own have relied on various forums and other anonymous open-source resources for answer explanations, students should be aware that these sites are also unlikely to have updates for months (if not years) following the release of the new exams.


More importantly, although these popular open-source explanations can be helpful in certain situations, I have come across so many "explanations" that are incomplete, inaccurate, or likely to mislead students in ways that could cause them to answer similar questions incorrectly in the future. Unfortunately, relying on these well-meaning community resources alone can thus be a serious misstep. These posts are not subject to verification, peer review, or quality control. Anyone can post an unauthorized explanation, including those without any more understanding of the question than the student looking for help. Accordingly, we recommend that students studying on their own avoid these unverified resources and instead take the time to teach themselves to understand each and every CBSSA question by cross-referencing trusted resources such as First Aid, Pathoma, and the UWorld answer explanations.


Although this is a significant investment of time and effort, in my experience, the majority of those who excel on Step 1 have not only memorized the content of the CBSSAs but have also acquired an in-depth understanding of the concepts tested. It's tempting to think that reading unverified explanations could expedite this process, but the risk of introducing misinformation or misunderstanding is too high, particularly in light of the often career-determining nature of USMLE Step 1 scores. To those outside of med school, completing and self-teaching up to 11 five-hour practice tests may sound like torture, but to those who achieve their goal scores on the USMLE Step 1, the effort will undoubtedly be worthwhile.



The author, Chanan Reitblat, is an MD/MBA student at Harvard University. He is the Chief Medical Tutor and Co-Founder of USMLE Pro. With over 1,000 hours of 1-on-1 tutoring experience, Chanan has helped his students increase their Step 1 scores by 65 points on average. To speak directly with Chanan for personalized advice on how to excel on the USMLE, schedule a free 15-minute phone call with him here.

Please note that usmlepro.com is not endorsed by or affiliated with the National Board of Medical Examiners (NBME) or Federal State Medical Boards. "USMLE" is a trademark of the NBME and is used pursuant to the Fair Use Doctrine.

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