<p>Alexandre --</p>
<p>You hit the nail on the head. First, because the name brand of the "University of Chicago" in non-academic circles is not as strong as the name brand of Harvard, Yale, or Princeton, The University of Chicago tend to get fewer applicants in any given year. </p>
<p>Second, my guess is that because of their name brand, the Ivies get a fairly large number of "what the hell" applications from students who have absolutely no shot of getting in -- students with 2.9 gpas and 1100 sat scores. I would be that The University of Chicago gets a great deal less of these types of applications.</p>
<p>Third, it takes a special breed of person to be drawn to The University of Chicago. I have never known a graduate from The University of Chicago describe their undergraduate experience as "fun". While I think that the old adage that The University of Chicago is where, "the fun goes to die" is a bit over-stated, the academic pressures placed on the undergraduates population at The University of Chicago (whether it is self-induced or institutional) is undeniable. Given these pressures and the fact that you have an academic institution of comparable academic reputation less than 30 miles away and in a much more livable area, you can see why The University of Chicago's acceptance rate is relatively high when comparing it to schools of similar academic reputation.</p>