<p>Numbers are not my strong point and this is not a professional opinion but I think selectivity is somewhat subjective. There is an objective part: you could perhaps say that the schools with the very highest midrange SATs are the most selective, or the schools with the highest percentage of valedictorians or something similar, but that probably wouldn’t show the whole picture. I suspect different schools weight their criteria slightly differently and that intangibles come into play, as do social, economic, and geographical diversity and whatever else a school is looking for to strengthen its overall community. So short of knowing that a given set of schools is incredibly selective, it would be hard to do more than group schools–too many gray areas and sliding scales I imagine to do a strict numerical one-by-one ranking.</p>