why would an applicant be deferred?

i mean this in a general way. ik that sometimes people are deferred early and then get in (though unlikely), and i hear a lot that it is used to wait and compare the applicant to the larger pool, but don’t they kind of know by this point what they are looking for? and is an applicant deferred when some members vote admit and some reject? any thoughts appreciated—just wondering i guess how deferral is used.

In the early pool, many colleges are most concerned with using the admit spots to fill ‘institutional needs’. If you’re not one of those you may get bumped out to the regular pool even if you are what they are looking for. Colleges also have a set number of students they will admit early, so there could be kids they really want, but they just don’t have room. Some schools also use deferrals very liberally (think Yale is one of those), while others (like Stanford), use deny more than defer.

52 Reasons You Got Deferred (and what to do about it): http://thecollegematchmaker.com/52-reasons-you-got-deferred-and-what-to-do-about-it/

Along @wisteria100 train of thought. The Yale deferral rate for the Class of 2022 was 55%. Harvard’s was 74%. Stanford historically defers around 9%. If you get rejected by Harvard in the early round, you likely have significant defects in your application and/or are shooting too high. If you are deferred by Stanford, you likely have a very strong application (competitive for any highly selective) and maybe some new data will get you over the top in the RD round. It’s a little harder to make assumptions after a Yale deferral/rejection, although I’d say an outright rejection probably means you should recalibrate your safety, match, reach assumptions, and I would definitely get another opinion on your main essays.

Top schools generally want to admit the best possible selection of applicants. They admit a (roughly) fixed number of seats; they usually limit the EA/ED seats admitted, because over-filling in the EA/ED round could result in having to wait-list a stronger applicant in the RD round. As others have noted, a large portion of the EA/ED admits are those who fill “institutional needs”.

Deferring to the RD round allows a school to keep its options open on candidates who are worthy of admission but who don’t fit into the space allocated for EA/ED, but requires a re-review. Stanford prefers not to re-review given the volume of their RD applicants. HYP are more willing to re-review, and hence more likely to defer.