Sometime not too long ago there was a blog post or article covered on HN, about data showing student scores on some academic achievement measure over time. If I remember, all students generally improved on this measure throughout undergrad, and there was some average tendency for universities with higher average entering standardized test scores to have higher scores, but the effect seemed to be mostly driven by the students. That is, it wasn't that some schools accelerated scores more, it was that they just tended to select for higher-performing students. Also, the signal provided by school, if I remember, was relatively weak. The author was basically arguing that universities in general provide some educational value (or students just learn over time; there was no control of students who didn't go to college) but that the ranking was by and large just a signaling thing.

I can't find it now though because all the search terms I can think of just return a bunch of other stuff related to universities and students.