NBME 26-NBME 31: Which is the Best Predictor for Passing Step 1

This blog was originally published on March 21, 2023, and was updated in August 2024 for new information.

There are innumerable resources available for Step 1 preparation. No one study approach will work for everyone or guarantee success. Whatever plan or resources you decide to use, everyone will need to use practice questions and practice exams. These help to gauge how well you understand the content that will be tested in Step 1. In this post, we will review the NBME 26 – 31 to help you understand which of these is the best predictor for passing USMLE Step 1. We recommend taking a look at our 10-Week Step 1 schedule or our 6-week Step 1 schedule to help you get on your way to Step 1 success!

Practice exams are one of, if not the most important factor of your Step 1 preparation. They provide a benchmark of how you are performing. Practice exams can also help you predict whether you are ready to take your exam. They are also very useful for breaking down your performance by subject area. This can help you identify areas where you might need to focus your studying. Taking all your practice exams seriously and thoroughly reviewing them is essential to your preparation for Step 1. You will get experience with the types of questions the USMLE will ask and review much of the content that could be covered on your exam.

Which Practice Exams are Available?

There are currently six practice exams offered by the National Board of Medical Examiners (NBME) for Step 1. These are called Comprehensive Basic Science Self-Assessments (CBSSAs). The current forms available to students for purchase are Form 26 – Form 31. Each exam is $60, however, your medical school may provide you with vouchers to take one or more of these practice forms.

Each exam consists of four sections of 50 questions with a total of 200 multiple-choice questions. You can take each exam at a standard pace (1 hour and 15 minutes per section) or self-paced (5 hours per section). I recommend all my students use standard pacing in order to simulate the timing of the actual USMLE. In addition to the NBME exams, there are two UWorld Self-Assessments (UWSA) that are also good resources. If you want even more practice questions, the NBME also offers a Step 1 Orientation that includes 120 practice questions. This is known to many students as the “Free 120”. These questions are also similar to the style you will see on the USMLE, however, there are no official answer explanations to help you review the questions.

Which NBME Practice Exam is the Best Predictor for Passing Step 1?

Students often want to know which CBSSA is the best predictor for passing Step 1. This is especially important if you may not have enough time to take all the CBSSAs. Many students ask, “Which is the most important NBME?” or “How do I decide which NBMEs to take?”

Based on prior informal student reporting, NBME 28 and UWSA 2 are the most correlated with Step 1 performance. Given this information, it might be a good idea to take these two exams when you are further along in your dedicated study and closer to your actual test day. Additionally, the newest NBME forms tend to be the most representative of current Step 1 content, so I would recommend taking NBME 31 towards the end of your preparation. However, all the CBSSAs that are currently available as well as the UWSAs should be helpful predictors of your performance.

The NBME consistently updates the available test forms. The questions are reflective of the style and content that you will see on the USMLE Step 1. When you take a CBSSA, you will receive an estimate of your likelihood to pass Step 1 if you took it within a week of your practice exam. The NBME recently updated the estimated probabilities of passing Step 1. 

What do the updated estimated probabilities of passing Step 1 mean for you?

 In July 2024, the NBME released an update on the estimated probability of passing Step 1 based on CBSSA performance. For scores between 62 and 68 on the CBSSA (the range corresponding to low passing performance), the new estimated probabilities of passing Step 1 are 1 to 4 percentage points lower. For example, the estimated probability of passing for a score of 64 is now 92% (previously was 95%), and for a score of 68 it is 97% (previously was 98%).

Overall, these changes mean that you will need to achieve a higher score on CBSSA prior to taking Step 1. Although the low passing range is 62-68, I generally recommend that students achieve a score of 70 on a CBBSA prior to taking their exam. 

Enhance Your USMLE Step 1 Preparation with Community Insights and Expert Guidance!

Navigating the vast array of resources for Step 1 can be a challenge, but practice exams are a crucial component of your preparation. They provide a clear benchmark for your performance and help you gauge your readiness for the exam. Join our newly established subreddit, r/ask_a_usmle_tutor, where you can connect with experienced MD tutors and fellow students, and get valuable insights on practice exams, study strategies, and more. Join us now at r/ask_a_usmle_tutor

Looking for personalized guidance? Our experienced tutors can assist you in deciding which practice exams to take, create an ideal study schedule, refine your test-taking strategy, and provide the motivation needed to succeed on the USMLE Step 1. Schedule your complimentary consultation today to explore how we can support you on your journey!

Looking for a tailored Step 1 schedule? Consider checking out our 10-Week Step 1 schedule or our 6-week Step 1 schedule to kickstart your journey towards Step 1 success!