3 months late and you can still get your rotations done before the residency start (so could remain in the original class), 6 months maybe not, its close.  So your saying your school moved 20% of the class into the following year?  To my knowledge, from doing COCA site visit things, any student who doesn't graduate with their original class (except I believe for fellowships) counts as attrition, even if they go on to graduate.  So that's 20% attrition right there, plus whoever else they lost along the way (every school loses some people).  Is this a new policy?  It would be hard to believe such high attrition wouldn't get on COCA's radar.  I also found it interesting that they would have a policy that allows them to make a student "repeat" an entire year (presumably a year of board prep?) even though they have passed all their classes but didn't do well enough on a test exam.