Although we don’t have data from the CDS about the number of waitlisted students who are offered admission but decline, I’d guess that the yield for these students is higher than the typical RD yield, and that some colleges use this to their advantage.
Many colleges are sending out a blanket “are you still interested in staying on the WL” email after all decisions have come out and the May 1 deadline has passed. Why? To know which students are still in play. Can someone who has already been accepted to their dream school indicate they’re still interested just to score another notch on their belt? Sure. But many will pass.
Obviously many students who really want to get off the WL send additional LOIs and other materials over the summer—another strong indicator that a student is still in play and would be more likely to accept an offer of admission from the WL.
I’ve also been reading more and more posts on other forums about waitlisted students (who’ve already opted to stay on the WL) getting a call from a college asking if they’re still interested in attending before an offer of admission is made, then being given a very tight deadline to respond.
If a waitlisted student says upfront, “no—I’m committed to Yale,” is the college recording this as an official acceptance? They should be and I’m sure most (like Williams) do, but some may not. The phone call means there’s no written record of an offer being made.
All this to say that colleges have a pretty good idea of who is more likely to accept an offer of admission after May 1, and will use this information to maximize yield when it’s necessary to go to the WL.