I did a fair bit of research on how the colleges' waitlists work coz I too was waitlisted by Cornell. Waitlists are trickier than they actually look. Many people might already know this but I'll again explain by an example:
Suppose a college has 70 seats to offer and in the last few years, the mean yield (or acceptance rate) is 50%. Keeping this in mind, colleges give out admissions more than what they could accommodate, like 120 or so, in all their rounds of admissions. Number of admissions to give in the subsequent rounds are decided based on the number of acceptances in the previous rounds. All this while, they also send out waitlist to some applicants whom they think are qualified enough for the program at their college, but there are some other applicants with similar background, and just better than the waitlisted applicants in some aspect or the other. The size of the waitlist can be small or big and can vary across colleges. Let's say the size of waitlist in our example is 50.
Now out of 120, suppose 65 had accepted the offer. Now, colleges try to fill out the 5 seats from the waitlist of 50, most of the time trying to balance out the diversity, in terms of gender, work ex, geography etc. Now if you see what had happened, the total number of offers made are around 130 with 70 accepting and the yield is just above 50%. But the chances for waitlisted applicants are purely out of luck with 1 in 10 getting admission.
I was just trying to put the actual picture and no way intend to discourage. This is a generic process but there might be slight differences in the procedures individual universities adopt. All we can do is just pray to convert the waitlist into an admission, especially if the college is the first preference out of all.
