Hey there.

I’m looking for a measure of intra-individual variation over time. I am not
really running mixed models, but remember from the literature that this
basically equals the question "Do I need random slopes or not", so maybe
you can offer some help.

Basically I am looking at depressive symptoms over time in a clinical
trial. What I am really interested in is comparing week 1 vs. week 12. But
I am not sure whether week 1 and 12 offer a lot of information about the
person, or whether people vary a lot within themselves over time and
therefor I should use an aggregate score of say weeks 1-3 and weeks 9-12 to
compare.

I plotted some individuals to see whether the trajectories look kind of
stable or kind of all over the place, however with N=4000 and an ordered
outcome it’s really hard to make sense of individual trajectories with more
than 10 people

I really appreciate it, thank you! I hope some day someone will come up
with a test that has an outcome of 0.0 to 1.0, and everything between .5 or
so means no random slopes ;)

T.

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