If you have a 3.6+ and a 20+ you will probably get in somewhere.
If you have a <3.0 and a <18 DAT, you probably won't get in (although I'm sure plenty of people with these stats have been accepted in the past).
If you are somewhere in the middle then it could go either way with your chances improving as your GPA, DAT scores, and other things on your app look better.
If you are just starting college you should make it your goal to be in the high GPA/high DAT score group so that you will end up taking the guess work out of your chances of getting in. I don't know of any people with a 3.8+ GPA, a 21+ DAT, an app that was turned in early, and that applied to multiple places that didn't eventually get in somewhere.