<p>You can’t draw any conclusions from raw statistics without considering the variables that go in to impact the statistics. Without looking at statistics in context, they are simply numbers. </p>
<p>Even US News knows that – their algorithm factors in an “expected” graduation rate because they know that the students with higher stats going in are more likely to graduate in 4 years than the student with the weaker stats. </p>
<p>There is also considerably more economic pressure for students at private colleges to finish in 4 years than for students at public colleges, particularly because most private colleges limit their financial aid to 4 years. So how is the middle-class student who decides to hang on for an extra semester at Yale going to come up with the $20K tuition for that one extra semester? At the public university, the question may be framed in reverse fashion — the student is far less likely to be the beneficiary of generous financial aid - and the best way to come up with the $7K tuition for the next semester may well be to take off from school and work full time to earn the money.</p>