JMP Pro 13 allows assigning up to two Subject terms for the Exchangeable Structure of the Repeated Structure tab in the Mixed Model dialog. Can anyone give me an example where two subject terms would be appropriate or preferred for repeated measures longitudinal regression? In particular, I'm wondering whether I could use ID and Eye as Subject terms for the partial dataset listed below (where Eye is nested within ID) and Year_Cat as the repeated term. Or should I use only ID as the Subject term and concatenate "Eye" and "Year_Cat" as the Repeated term? Thanks in advance.
|ID||EYE (right=1, left=2)||YEAR_CAT|
As an example, in measuring the effects on achievement scores of students where students are nested within schools, two subject terms--school and students within a school--would be appropriate.
In your case you can specify the random subject effects as shown below and leave the default Residual for Repeated Structure:
If I believe the difference in the measurement between the left eye and right eye is random then I would use the first option. If not, then the second.