How to do it?
Analysis==>Mixed Model, then you got diaogue 1 as follows. ID shuold be put be included as subjects. Year should be included as repeated, cause I measured multiple times by different year.
The most hard decision to make is which Repeated Covaricance Type to select, there are a lot of choices, the most used ones are:
- Unstructured: you have no idea of the correlation of repeated measures, SPSS we estimate all the correlation independantly (r12,r13,r23,r14,r24,r34).
- Scaled Identity: no correlations at all, r=0.
- Compound Symmetry: all correlations equals r.
- AR1: (r, r^2, R^3)
- Toeplitz:(a,a,a,b,b,c)
- Another choice is “diagonal” which assumes no correlation between the random effects.
Then you determing the fixed effect variable:
And the random effect variable:
