There are several practice exams that can be taken in preparation for Step 1. Most commonly, students utilize UWorld Self Assessments (UWSA) and NBME practice exams known as Comprehensive Basic Science Self-Assessments (CBSSA’s). NBME is the same company that writes the actual USMLE exams. The NBME also publishes practice tests for Step 2 which are known as CCSSA’s.
Clarification: Due to the fact that CBSSA’s are written by the NBME, many students will refer to CBSSA’s as NBME’s. The two words are basically interchangeable. If you hear someone say NBME 28, that is the same as CBSSA Form 28. NBME is the more common term used by students but when actually purchasing a practice exam, you will purchase a CBSSA.
UWSA’s consist of 4 blocks of 40 questions taken over 4 hours. CBSSA’s utilize 200 practice questions split into four blocks of 50 questions. For CBSSA’s each block takes up 75 minutes and the total CBSSA exam takes 5 hours. There are currently two UWSA's available and six CBSSA's available (Forms 26-31) for Step 1. Both UWSA’s generally come with a subscription to UWorld and CBSSA’s cost $60 each through the NBME website. There are other practice tests available from other companies but the vast majority of students utilize practice exams from either the NBME or UWorld.
How many practice tests should you take for Step 1?
In a perfect world, I would love for every student to take all available CBSSA’s and consider both UWSA’s. One study showed that the ideal number of practice tests for Step 1 performance was 6-91. Taking all available CBSSA's would help you reach this threshold (6). I recognize that recommending all the practice exams does have financial ramifications. Each CBSSA costs an additional $60 so taking all 6 costs $360. I can't decide whether $60 is worth it for everyone because I know some people are in very difficult financial situations. Try to budget for these exams early on when preparing for Step 1 because I feel these are an EXTREMELY wise investment if you can afford to take them.
Every student should aim for one practice test (CBSSA or UWSA) per week during dedicated. This helps you track progress and see when you might be plateauing. For those who start earlier, you may want to take several in the pre-dedicated period so that you can start gauging your progress earlier on. Testing early will show you your areas of weakness so that you can address them sooner. The NBME has an excellent tool to help you track your performance on NBME's longitudinally. It will help you see your overall performance, but it also has breakdowns for specific subject areas that can be a useful way to identify strengths and weaknesses. If you don’t take your first practice test until dedicated, you will have 4-6 weeks to correct those deficiencies. If you take a practice test 6 months from your exam date, that leaves you more time to fix any issues. Plus, taking several practice exams before dedicated makes it much easier to reach that ideal threshold of 6-9 practice exams.
I Don't Feel Ready to Take My First Practice Test
Not feeling ready is normal. Nobody wakes up and thinks to themselves “I’m dying to spend 4-5 hours exhausting my brain in preparation for a test that is still several months away”. You may never feel ready but you have to start somewhere. The sooner you start, the earlier you can plot that first data point and figure out where you are in relation to your goal.
Which Practice Test (NBME) Should I Take?
Every year or two new CBSSA forms are introduced and one or two older forms are retired. The majority of studies about the predictive ability of CBSSA’s looked at forms that are now retired so there is less known about the ones that are currently available. If your score is not above the "Low Pass" line then you may need to adjust your gameplan. Outside of that it doesn’t matter as much about which CBSSA you take and when you take it but more practice tests are always beneficial.
What is the "Low Pass" Line?
Before Step 1 transitioned to Pass/Fail, NBME's provided a three digit numerical score that allowed you to gauge your performance relative to the passing score as well as your target score. Everyone's goal is now the same for Step 1 (Pass). While all passing scores will appear the same, it is helpful to know how close a student is to passing when taking practice exams. The NBME score report you receive after taking a CBSSA attempts to provide some clarity on where you stand relative to passing as well as the overall average performance. Your score report will look similar to the example below.
There are several important numbers that the score report provides. First, the total equated percent correct (TEPC) score is similar but not identical to the percentage of questions you answered correctly on a given NBME. The reason they are not identical is because the NBME attempts to normalize that number relative to how difficult the exam was. So, a hard NBME where a student answered 65% correct might have an TEPC of 69% to make up for the fact that the exam was harder than others. This allows the NBME to compare apples to apples when looking at data from one NBME to the next. The NBME also states that this number is equivalent to the amount of content that a student has mastered relative to the total percent of available content tested. I feel this definition is less important because there is a massive amount of content that is testable and CBSSA's only have 200 questions to try to gauge your mastery.
Second, the example score report plots your TEPC on a bar graph relative to other students performance. This shows you how your TEPC compares to your peers. From the example above you can see that the TEPC for most students was between 71-80 with significant percentages also falling between 61-70 and 81-90.
Third, the score report shows you the Low Pass (LP) range. LP signifies the scores that are still considered passing but are very close to the Pass/Fail Line. In the example above, it appears the LP range is roughly 62-68 with the example score just above the LP line. This is important because scores within this range would likely pass the exam but there is less certainty because the difference between a students score and the Pass/Fail line is small enough that a student could fail in certain situations. Having a bad test day or randomly being given a higher percentage of questions that a student isn't as strong in could potentially lead to a failed exam.
Fourth, your NBME score report will provide an estimated chance of passing Step 1 if taken within 1 week. In the example above, the student had a 98% chance of passing if they tested within the next week. The timing is important here because you may be taking NBME's early in the process or at the beginning of dedicated. These tests are far more than 1 week from taking Step 1 so this metric is slightly less important early in the process. As mentioned previously, the goal with those early exams is simply to plot an initial data point or two so you know where you are starting from. The estimated chance of passing Step 1 is based off data from the NBME exams taken by students in 2020 who then took the exam shortly after. This data is updated periodically by the NBME. For a more thorough explanation of an NBME score report, watch the short video on the NBME website here.
I Did Really Bad on my USMLE Practice Test. Am I Doomed?
My football coach in elementary school used to say “When you win big, you are never as good as you think you are. When you lose bad, you are never as bad as you think you are.” That saying has stuck with me to this day because it’s true and it applies here. If you scored a 65, 71, 73 on your previous 3 practice tests and all of the sudden you drop to a 64, it is probably an outlier. So, maintain perspective and don’t get too wrapped up in doing poorly on one particular practice test (You aren’t as bad as you think you are). The opposite is also true for when you score really well on a practice test. That is not a time to stop working hard because it might also be an outlier.
Should I Review my USMLE Practice Test? If so, how should I review it?
The answer to the first question is absolutely. While most students take these exams because they want a score prediction, there is significant value in reviewing the exam afterward. For CBSSA’s and CCSSA’s the questions were written by the same people who write USMLE exams so the topics tested are likely to show up again. In addition, the practice test is full of practice questions so you need to analyze your answers on a question-by-question basis to determine where you fell short from both a content and strategy perspective. The NBME offers a more detailed breakdown of your performance for each particular organ system as shown in the example on the next page which helps determine content areas that may need work.
Once again, the NBME gives you an estimated percent correct (EPC) for each subject area and shows the average EPC for all test takers. You can see from this example that the student had scores in General Principles, Multisystem Processes & Disorders, MSK + Skin + Subcuataneous Tissue and Biostatistics that were all at or above the overall average. These were the students strengths. We also see that the Score Comparison column still has the student performing the "Same" as the average in all of the previous strengths mentioned. This is a result of variability so even though the student's EPC for a given subject area may be higher than the average EPC, the difference is not great enough to definitively say they performed at the "higher" level.
We can see that areas like Reproductive & Endocrine and Cardiovascular were below the group average so these are areas that should be addressed. When you look at % of Questions (far right) this can help you prioritize which areas are most likely to be tested again. In this example, the student should prioritize Reproductive & Endocrine over Cardiovascular because Reproductive & Endocrine makes up a greater percentage of the exam.
Sources
1. Seal ZA, Koek W, Sharma R. Correlation of Medical College Admission Test Scores and Self-assessment Materials with the United States Medical Licensing Examination Step 1 Performance. Cureus. doi:10.7759/cureus.7519
