Most colleges have the ability to graduate close 100% of their students.

If a school only admits students who have at least two years at another college with high grades, their graduation numbers will skyrocket.

A highly selective college, like Harvard, could even refuse to grant credit for those two years.

There are less nefarious ways of selecting a class of likely graduators: leadership in extracurriculars is highly correlated with post-secondary graduation.

Foreign students with limited English fluency have very low graduation rates. They could (should?) be excluded.