If you are concerned about graduation rate, consider this:
How many students must work while they are in school and can only attend part-time (or not-quite-full-time)?
Is it a commuter school? They tend to have lower (or longer) graduation rates.
Look at the requirements to graduate: are there a lot of hoops to jump through? Are the classes hard to get into? Might that set your child back because he/she couldn’t register for X requirement and it’s only offered one semester?
The first two questions impact the graduation rate a lot, the last set will impact YOU.