Most places interview about 10 per spot. I know the SF program only interviews about 12 people for 3 spots, and some places (none come to mind right now) interview 15 or more per spot.

I agree with most doing the 10:1 ratio. Cinci and Ohio State interviewed about 15 for every 1 spot. Pitt interviewed 106 for their 8 spots. Georgetown interviewed like 40 for their 3 spots, but this is in addition to their 20+ home students going into ortho. so those 40 were fighting for only 1 or 2 spots. Not a very high yield. Some of the very competitive & more desirable (at least in some peoples' minds) interview less than the 10:1. for example, Harvard interviewed 79 for their 12, HSS did about 50 for their 8.