I have volume and crash data for 7 years from several roadway segments. I used segment ID as my subject and Year as within subject variation. Then I used volume as predictor and total crashes as dependent variable. In the model tab, I used ln(volume) as main effect and year*volume as interaction. The output that I get, is it already taking care of the correlation? How do I get the paramter for yearly correlation? I am learning SPSS and really could use some help.