well columbia has two rounds of admissions. the majority of applicants find out in early feb. i am pretty sure this is for people that have interviewed by january. then there is a much smaller group of decisions sent out in mid march for those that interview in jan and feb and march (although i dont know if they interview this late). i think waitlisted applicants find out in march and they pull quite a few applicants from it. i would regrettably admit that there is not much time left to hear from columbia, as they have not had any delays this year (non-amcas).
yale is a little different. i know people complete in sept. that have just been offered interviews. a friend of mine recently talked to their head of admissions and he admitted that they were pretty badly hit this year with amcas and they are pretty disorganized and backed-up. they have yet to even cash my check and my file was complete nov. 1. there is still more hope with yale than with columbia; i am sure they interview through march and give out all responses at the end of march. they are appearing to give out interviews on a less chronological order than the other schools.
also stanford i know rejects as soon as they decide on it anytime in the process. so no news from them is definitely good news. the same goes for pitt and einstein.
-look at it this way: there are at least two good months of interviewing left at each school, and they are all just about finishing getting through the last month of completed apps at least once. they have to pull the next two month's interviewees from somewhere, right?
you may wish to look for an excuse to call. ask about something trivial in your application (like you never received a complete status notification). anything just to get them to dust off your file and pop it to the top of the list. i've noticed this has worked for me several times (got an interview within a week of 3 phone calls).
anyway, good luck.
