This is going to vary a lot from program to program.
We have a weighted points-based system (as I imagine most programs do), and I honestly don't know how much weight is given to the interview. I've forgotten that number because in the end, we vote based on the "overall picture". It's not as scientific as you'd think. There is a lot of gut-instinct there when it comes down to the wire.
The "easy" ones are the superstars who are just all around superlative in everything. They have fantastic grades and board scores, they are impressive and genuine and likeable in interviews and seem to get along with everyone. Also easy are the non-rankers, the ones who fail one of their steps more than twice, got kicked out of another residency program, had and overall picture that was very weak or who made such a dismal impression at the interview that there is no doubt that we won't rank them.
The other 90% of you fall in between. That's where the hard work is for the committee. All things being essentially equal in that 90%, meaning you all have passed your boards, fall somewhere between the top 10% and bottom 10% of your class, have decent letters, etc...that's when the interview can tip the scales.
A few things to remember:
-if you act so nervous that we can't tell who you are, well, we can't tell who you are and that's a big part of the process
-if you are being fake, we can tell.
-the questions you ask US tell us a lot about you. If you don't ask any questions, we assume you aren't that interested in us.
-be yourself at the resident dinner/lunch and don't put on a different face for the residents that you do for the committee. We talk and share information. You are "on" from the moment you arrive until the moment you leave.
All that being said, in the end when we hash it out and rank applicants, we use the points system as a guide, but it's only a guide. It may not be terribly scientific, and you may not want to hear this, but the process is somewhat subjective. It has to be, because there is no way to numerically quantify a human being. We can do it with grades and accomplishments, but when you factor in the interview, their personality, the impression they give, the numbers kind of go out the window unless you are at the very top or the very bottom.
Bottom line: be yourself, relax, come with some real questions that show you have interest in us, and you will very likely end up at the program you are meant to end up at.
The process is imperfect, but it works.
