Sounds like you want to do some statistical test. What is your hypothesis?
In same year, Civic is more expensive than Corolla or
1997's Civic is more expensive than 1996's Civic (Fei Huan!).
As a new immigrant without stable income, 4-6 years old Civic and Corolla are good choices. You may also consider the following:
Milage, safety, resale value.