What would happen if all admitted students committed?

I know the odds of this happening is incredibly unlikely to happen. So unlikely, in fact, it’s probably not even ever discussed among college admission counselors. But I’m interested because last year, more people committed to Michigan than they expected, forcing them to deny some freshman housing. And I know that the number they admit is based on yield from previous years; so if a college has a yield rate of 50% and they have spots for 6,000 students, then they’ll admit 12,000 students (this is very clean-cut and I know there are many factors and some “buffer room” in case anything goes wrong, but let’s pretend for now this is exactly how it works). Given the “freak-out” at Michigan, I was wondering what would happen if a college’s yield rate for one year suddenly jumped to 100%? Again, I know this is soooooooooo unlikely, but there is a very, very, very tiny chance of this happening.

First off they can admit in waves and control ED1 and ED2 before RD comes into play.

So then they could effectively have 50% of their class filled before the variables of RD yield are in play.

That being said, many students are applying to more schools and getting more acceptances these days. A student can only attend one college so the yield at all the others goes down.

Why in your hypothetical would a single school see their yield dramatically rise in a heartbeat?

Admissions departments pay a lot of money for software that predicts yield based on admitted student profiles, past history, and other factors. While weird unpredictable stuff can happen, it’s highly unlikely.

It happens occasionally. First, the schools will aggressively offer gap years to already admitees. Anyone who even hints at the possibility will be contacted and strongly offered incentives to delay matriculation.

Secondly, they go into crisis mode – which includes finding housing for the unexpected surplus. Contracting nearby apartments/hotels, offering incentives to upperclassmen to move off campus, transforming every available living space into dorm rooms (including putting 3 into previous doubles, altering dorm lounges, etc.). It’s happened before and will likely happen again.

What also happens is the subsequent year, they admit MUCH less (UMich’s class of 2019 was much smaller due to unexpected numbers of 2018s who matriculated)

We all know that yield wouldn’t be 100% unless a college forced students to attend using its own private army. With that out of the way, I’ll answer this as a hypothetical.

The immediate consequence would be an increase in undergraduate enrollment (duh). The magnitude would depend on the yield rate in previous years.

At Harvard, yield is currently 81%, so if the other 19% enrolled that would represent approximately a 25% increase in the size of one freshman class. The undergraduate population would jump by 1/4 of 25% (25% increase in one class out of 4), or some 6.25%.*

*Obviously, there’s a little wiggle room. Actual yield is 81%, not 80%. Maybe one freshman class is larger than others by design. Admitted students who enroll aren’t going to fill 100% of the freshman class, which is why the waitlist exists. This ignores transfers. I’m analyzing this in a quick-and-dirty manner.

At the other end of the spectrum, there are schools where yield is about 20% (and some where it’s lower still, but I’m going to make 20% my arbitrary comparison). These colleges admit about 5 students for every spot in the freshman class. A yield of 100% would increase the size of their freshman class fivefold. The undergraduate population would double.

This analysis will be a little off in the case of schools like Cornell or the UCs, which accept a significant number of transfers, but I’m not trying to write a thesis here. If anyone’s happy to crunch those numbers, be my guest.


Now, we can look at the effects of such an increase in the student body. Some are obvious, others less so.

Among the commonsense assumptions:

-Class sizes increase. It isn’t easy for a school to increase its faculty by 6% between enrollment deadlines and the following fall. Probably easier for West Podunk community college, while professors that (insert Ivy here) would consider up to scratch are probably less numerous among the pool of academics seeking a position. It’s all but impossible to double he size of a school’s faculty in the space of a few months. Fewer professors/student --> larger classes

-More TAs and graduate students teaching introductory classes. This would be done in an attempt to mitigate the above change.

-Housing can’t be guaranteed for everyone. It takes X months to increase the number of dorms on campus by 6%, or 100%. I think we can safely assume X is more than 4 or 5, which is what a college would have. Maybe students are offered rentals nearby. Perhaps the college buys some nearby houses or hotels. The university’s endowment would likely take a hit.

Other possible side effects.

-Upward pressure on prices in the area (esp. in the case of one-college towns). A few thousand extra students probably won’t raise NYC inflation considerably, but if enrollment doubled in a town where 25% of the population are students at X college, that would have a real effect.

-More competitive landscape for internships, jobs, leadership positions, etc. in the area. Again, the above caveat applies. NYC won’t run out of internships that easily, but a small town might.

-Lower acceptance % and higher yield next year. 100% yield --> higher ranking --> more applicants (and students willing to commit) --> college has more applicants, but needs to reduce the # accepted to plan for higher yield --> lower acceptance % and higher yield.

I’m sure there’s something I’ve missed, but I can’t be troubled to spend more than 10 minutes on this question.

The scenario where 100% of accepted students attend a particular institution is virtually impossible. However, some years schools do have higher than anticipated yields and, as a result, get more incoming freshman than anticipated or desired. The generally means a number of forced triples in freshman rooms and some crowded freshman intro classes.

For Michigan, you are thinking of 2014, not 2015. They were aiming for 6000 enrollees and received about 6500. All freshmen did get their guaranteed dorm housing. Some older students were displaced from dorms to apartments that Michigan Housing helped them locate. There was one particular convenient apartment building that many went to.

Michigan was much more careful managing acceptances this past Fall as their yield has been consistently increasing. More deferred and on wait lists.

Besides frosh dorm space issues at more residential universities, popular courses and majors may be oversubscribed.

@wayneandgarth If you look at my post, I mentioned the classes of '18 and '19, the entering classes in the falls of 2014 and 2015 – just like you cited.

Yep - thanks @T26E4. I missed that. I was answering too quickly after reading the OP’s post. Thanks!