The paper said a raw score of 71-80 (53% correct) carried an 80% probability of passing.
A raw score of at least 90 carried a 95% probability of passing.
Also, I will point out that yesterday's test was maddening as far as content and breakdown of questions by subject. Quit shoving topics down our throats that no one cares about or desires to make a part of their practice. I'm not sure how much I can say given we had to sign an NDA after the test, but those topics were ridiculous.
If there is a topic that is OWNED by another field, and that field is filled with subject matter experts, give it to them and quit forcing it on me, especially if there is ZERO reimbursement associated with it.
A generic example:
I did an IM internship, and I am able to do a pretty good job messing with HTN meds...BUT, I will never be as good a board-certified internist, and for that matter I should NEVER be the one managing BP meds because there are people out there who are better at it than I am! That is the case with a lot of PMR topics and it drives me nuts. The boards should be heavily weighted towards core PMR topics, namely the things we all do in practice - SCI, TBI, MSK, Pain, EMG, and Peds. All that other stuff is BS...
I took part 1 yesterday as well. I completely agree that the exam was all over the place. But anyway I called the board and got some good info about passing percentages. Basically they said they're really is no set passing score and the comitte has they're own criteria (whatever that is). That being said they said that overall for the past few years you needed to get 61% - 64% of the questions correct to pass and last year it was 64%.
Hopefully thid helps the answer to the question of the original poster.