Step I: Scoring

The NBME keeps this secret more closely guarded than the questions themselves. The two digit score is just an attempt to relate the scores from year to year (a 75 in 1990 should be the same score as a 75 in 2005, even though the 3-digit will be different). The 3-digit is not raw, it is a measure of how you do relative to people in your general testing group (i.e. the last year)

So...your two digit is set up to determine minimum passing (most states require 75) and the 3-digit is set up to determine performance in relation to other current test-takers. The minimum passing score is 1.5 SD less than the mean (very close approximation) and it may very well require 50% correct (that is the rumor), but not due to calculating # of questions, because 50 of 350 questions are 'test' questions that are not scored, but are used as figuring how 'testable' they are for future exams.

Hope this helps.

 

the scoring: nobody knows. stop asking.

 

or that...

 

From my (many) conversations with some ex-members of the NBME committee on test standardization...

The 3-digit score is a scaled (NOT raw!) score based on the number of questions you answered correctly, and also based on the relative difficulty of the questions. The 2-digit score is based on the 3-digit score.

Throw into the mix the fact that your test may have up to 50 "sample" questions (new questions written by the NBME and "field-tested" before they're actually added to the question bank). These don't count as part of your score.

 

Remember, a scaled score is any adjusted score. So if you got a 260 raw score and your score was adjusted to 262, then it's technically a scaled score.

From what I've been told, raw and scaled scores do not differ significantly.

Good luck to all who are taking the exam this summer. You all will do fine!