To add more confusion to the issue, I was a student living in the dorms during the 2000 census, and we did have a census worker come by.  She made it clear that we should fill the forms out as living in Columbia, since we were going to school there (i.e., living there at the time).  She also told us to make sure our parents didn't claim us on their forms, so as not to double count.  For what it's worth . . .