NBME 13 to Step 2 CK

NBME 13 carries no correction. NBME equates forms 10 through 16 onto a common score scale, so this one carries no correction: the printed score enters the projection exactly as printed. What changes the projection is how recently you took it, not which of these forms it was.

NBME 13 conversion table

Printed score to projected Step 2 CK range, for a form taken in the last month. The range is about a 68% band: roughly two in three students land inside it, which is why it is a range and not a single number. Take the exam further out and the band widens.

Rows shaded amber have a projected floor below the 218 pass line. Percentile is against LCME first-takers. Your printed score is never restated as a lower number: where a correction applies it lives inside the math, not on your report.

Blend several forms and add your exam date

How the projection works

Three steps, and the constants are published rather than described. Then it is shrunk toward the population mean of 250 with a slope of 0.79, which is what stops a single high form from projecting a fantasy. Then 9 points are added for the measured gain from practice form to real exam.

Fit on 258 real posted score reports and tested blind on 32 it had never seen: average miss 4.1 points, bias statistically zero. Reddit posters skew toward good news, so treat the range as honest rather than generous. Full methodology, including where the model stops being trustworthy.

Questions

Does NBME 13 convert directly to a Step 2 CK score?

Not one to one. A practice form and the real exam are different tests taken on different days, so the honest output is a range, not a single number. The projection shrinks your form toward the population mean and adds the measured practice to real gain, then reports a band around it.

Is NBME 13 accurate?

It is vendor-equated onto the same scale as the other modern forms, so it needs no correction here. Accuracy in the sense that matters, how close the projection lands to a real score, was tested blind on 32 score reports the model had never seen: average miss 4.1 points.

How much does the date I took it matter?

A lot, and more than most converters admit. Forms are weighted by recency with a roughly 21 day half-life, and the width of the projected range depends on how far out your exam is. A form from three months ago tells you much less than one from last week.

Other forms

• NBME 9
• NBME 10
• NBME 11
• NBME 12
• NBME 14
• NBME 15
• NBME 16
• UWSA 1
• UWSA 2
• UWSA 3

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