<p>Actually, no, the classes wouldn't be half full because judged on something called yield based on experience (how many % of students would enroll after being accepted), they can guess roughly how many students they'll get a year and hopefully fill up the freshmen and dorms though hopefully overly so!</p>
<p>If you were going purely by numbers, is is it better to judge a college based on its selectivity (% of students get accepted. Lower is better) or by the yield (% of accepted students enroll. Higher is better)?</p>
<p>Colleges start with the number they hope to enroll and then determine a higher number to admit based on historical yield numbers so that they end up with close to the number they want to enroll. Sometimes they end up short of the hoped for number of enrollees and sometimes they end up with too many (the latter of which usually causes a housing shortage in the dorms).</p>
<p>Stats provided for freshman as to test scores, GPA and class rank ranges are based on actual number who enroll and that number is usually determined about the second or third week after classes begin in the fall.</p>
<p>Yield can be influenced by a lot of things beyond the general quality of the school: how self-selective the applicant pool was, how good merit and need-based aid is, how on-the-mark the school is in its conversion efforts (good mailings to admits, good open houses), how hard its app is to fill out, and so on. You can't really use it as a good measure solely on its own.</p>
<p>Let me give an example, where rapidly changing numbers illustrative how elusive the meaning of such numbers can be: Michigan added essays a few years ago. Apps plummeted. What appears to have happened is that students who knew they were marginal for admission, or who were only going to apply to make Aunt Sally the Alum happy, or who had Michigan 18th on their college choice list, didn't bother. Essays made it more work than it was worth for a slim chance or an admission offer they never planned to accept. </p>
<p>Therefore, the app pool was smaller. The proportion admitted went up (fewer people applied, still need the same size class). And Yield also went up (all those "casual" applicants out of the pool). But did Michigan as a school change much from one year to the next? Not really.</p>