How Predictive Is NBME 15 for Step 2 CK?

NBME 15 has been submitted to Predict My Step Score 9,469 times and tracked against the real Step 2 CK results students went on to report. In that data, NBME 15 showed moderate predictive power: a clear link to the real score, with plenty of individual variation.

What is NBME 15?

The NBME Comprehensive Clinical Science Self-Assessments (CCSSA) — the numbered "NBME forms" — are written by the National Board of Medical Examiners, the organisation that writes Step 2 CK itself, and report an approximate 3-digit score. Each form is a distinct test: newer forms track the current exam blueprint more closely, and older ones are retired over time.

What is a good NBME 15 score?

In our data, NBME 15 scores ranged from 201 to 281. Real scores usually landed modestly higher than the NBME 15 score, but the link is real but loose: two students with the same NBME 15 score can finish well apart on the real exam. A "good" NBME 15 score is one that puts your likely outcome comfortably above the score you need — run it through the predictor to see where you stand.

When should you take NBME 15?

NBME forms work best as spaced checkpoints through dedicated study, roughly one every one to two weeks, saving the newest forms for the final stretch since they match the current exam most closely. In our data, the gap between NBME 15 and the real result was smaller than for most Step 2 CK practice exams — it holds its value close to test day.

Does it matter when you take NBME 15?

Timing matters twice over. First, a score from six weeks out is a snapshot of a student who then kept studying, so early tests tend to sit below the real result — much of what looks like "underprediction" is simply improvement after the test. Second, our predictor does not treat every score you enter equally: each one is weighted by the exam's R² and by how recently you took it, with a recency factor that decays exponentially from your most recent test back to your oldest, and your three most recent scores drive the final adjustment. Enter the days-before-exam for each test honestly — it changes the answer.

Enter your NBME 15 score

NBME 15 score

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Takes you to the predictor with NBME 15 already filled in — add your other practice exams there for the full prediction.

How NBME 15 compares

Wondering whether to take NBME 15 next? See which practice tests are most predictive.

NBME 15 vs the other NBME forms

NBME 15 is one of 8 NBME forms in our Step 2 CK data, and they are not interchangeable: predictive power differs from form to form. The others — NBME 9, NBME 10, NBME 11, NBME 12, NBME 13, NBME 14, NBME 16 — each have their own page, and the full side-by-side ranking is available to premium users. How predictive is NBME 9? · How predictive is NBME 10? · How predictive is NBME 11? · How predictive is NBME 12? · How predictive is NBME 13? · How predictive is NBME 14? · How predictive is NBME 16?

Frequently asked

Is NBME 15 accurate?

NBME 15 showed moderate predictive power in our data: a clear link to the real score, with plenty of individual variation. But no practice test is "accurate" on its own — most are taken while you are still improving, so the number you see is rarely the number you get. Combining your scores, weighted by each exam's track record and timing, gives a sharper answer than any single test. Predict your Step 2 CK score →

How far off is NBME 15 usually?

Like most practice tests, NBME 15 is usually taken while you are still improving, so real scores tend to come in higher. What matters is the size of that gap, and for NBME 15 it is smaller than for most Step 2 CK practice exams in our data. The exact figures power our predictor rather than this page — it corrects for NBME 15's gap and for when you took each exam, automatically. Run your scores through it →

Is NBME 15 or NBME 16 more predictive?

NBME 16 is more predictive in our data. The exact gap is part of the full ranking, which is available to premium users.

Where does this data come from?

9,469 NBME 15 scores have been submitted to Predict My Step Score so far. Whenever a student also reports their actual Step 2 CK result, the pair goes into the model behind this page; it was last refit on 2026-05-14.

Can't I just ask ChatGPT how predictive NBME 15 is?

Not reliably. A prediction is only as good as the paired data behind it: real NBME 15 scores matched to the real Step 2 CK result those same students went on to get. General-purpose AI models are trained on forum posts and articles, not on verified outcomes, so what you get back is a summary of anecdotes rather than a calibrated estimate. The numbers on this page come from students who reported both. Read more →

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Data refreshed 2026-05-14.

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