<p>Here's the PR description of its methodology:</p>
<p>Admissions Selectivity Rating</p>
<p>This rating measures how competitive admissions are at the school. This rating is determined by several institutionally-reported factors, including: the class rank, average standardized test scores, and average high school GPA of entering freshmen; the percentage of students who hail from out-of-state; and the percentage of applicants accepted. By incorporating all these factors, our Admissions Selectivity Rating adjusts for "self-selecting" applicant pools. University of Chicago, for example, has a very high rating, even though it admits a surprisingly large proportion of its applicants. Chicago's applicant pool is self-selecting; that is, nearly all the school's applicants are exceptional students.</p>
<p>With regard to admit rates (and student profile), it is helpful to note that the disparity in class size plays a not insignificant role (say - Cornell v. Dartmouth); some schools have more of a self-selecting applicant pool (UChicago); and some schools give out copious amounts of merit aid and overly use the waitlist to pump up their nos.</p>