I would presume that almost everyone interviewed is ranked....
Obviously they would rather rank the people who were the worst at their interview than people who didn't get into a residency anywhere...at least the people at the interview where qualified to be there...
I would disagree with this statement. In fact, I made a point of asking those who interviewed me "how many applicants do you rank" (word to the wise, if you do choose to ask this question, risk of which may be argued either way, you'd do yoursef a big favor if you didn't pose it to the coordinator as I found their answers to be very unreliable).
In my opinion, a program should have a vision of where it is, where it intends to be, and how it plans on steering the entire field of EM given that it is a very young specialty. If they take themselves seriously, and feel that their residents actually have something to contribute in agreement with their broader goals, then they should only be ranking candidates who can foster the type of environment ripe for that type of progress. If on the other hand, their sole purpose for the interview is to get a general idea of how to rank a bunch of names, then either they don't intend on leading the field or they don't take the role of your residents very seriously since it appears that one name is as good as another. For better or for worse, this was my line of reasoning and I actually placed a good deal of import on the question.
Some of the best answers I heard on the trail were from Cinci (my new home), Indiana, Yale, and JHU. All of them said something to the effect of "we only rank those we want." To muddy the waters a bit, you'll undoubtedly hear something like this at other places as well. The thing that really separated their answer from other similar answers was that these guys clearly knew what their goals and priorities were, and didn't really care if they went unfilled. I got the sense that they were confident enough to be satisfied with 80% of thier spots filled with people who wanted to be there and had something to contribute, than 100% of thier spots filled with folks whose visions contradicted their own.
Obviously, its a problem with your vision if you go unfilled year after year. But it deserves mention that from 2003-2007, according to NRMP data that I'm sure is available somewhere on google, the following EM programs have all gone unfilled at some point: WashU, Hopkins, Mayo, Duke, LSU, Iowa, Michigan, Michigan State and UMass. You'd be hard-pressed to find someone sane who'll argue that any of these are mediocre programs. But it is the risk you take when you narrow down your options. Of the programs that didn't fill this year, Yale was the only one where I interviewed. I came away very impressed, I didn't see/hear anything negative, and read nothing but positive feedback on sdn. The other interviewees were all from top-tier schools, and seemed pretty cool to hand out with. I ranked the program second b/c of a spousal job issue, and would've gladly ranked it higher absent those other factors. In the end, I don't really know if they would've ranked me, but I don't think I would've been bitter if they didn't. They had a good look at me, and if they felt that I didn't jive with where they were headed, then I think that would've been fine with me.
One last bit: I don't mean to discourage any future applicants from applying to any of the places that I've mentioned. They're selective as hell, but in a really good way. They'll do you the service of taking a really good look at you to see if you can be a part of their team. If you're gonna travel half-way across the country, the least someone can do is critically analyze you beyond the numbers. Trust me, interview season is expensive and exhausting. After your interview, the last thing you want to think is "was that interview really necessary...couldn't they just learn that from looking at my app."