What? "Improving", that is educating, students is the primary purpose of colleges. Seems perfectly reasonable to want to measure how effectivly they do their job.

The quality of the graduates of a college depend on a number of factors but probably the two most important are the quality incoming students and the college's ability to improve their quality. In effect colleges perform two functions: sorting and educating.

Sorting people based on standardized testing, high school grades, essays, recommendations, interviews and application details is a useful service in itself. However most of the value and almost all of the cost of colleges comes from educating not sorting.

The current college rating "system" can't possibly separate these two sources of quality. Clearly it would be something useful to know as within any group of similarly ranked colleges there will be differences in the quality of the education component.

All else being equal prospective students would choose the school that offered a best education. More applicants would to schools that were better at their primary mission, educating their students. In turn these schools could be more selective.

Building such a system will not be easy but should be very valuable. Please continue working on this Mr Gates.