jamovi

I would like to run a mixed model to see the differences in variables between two groups: control (n=7) and test (n=12).
I then have 12 subjects numbered from 1 to 12 and 7 subjects numbered from 1 to 7.
My 2 factors are: time (0/15/30) and group (con/test).

The mixed model gives me results, however, when I change for example subjects 6 to subject 5 (and subject 5 to subject 6), the results (p) change. Whereas they should not change because there are no subject switching factors.

Do you have a solution so that the order of the subjects does not influence my results?

Thank you,
Luca

That is an expected behaviour of the mixed model. The correct model should have each participant with an unique ID

Hello, thank you very much for this answer!

So, is it a problem or not if we compare 2 different populations with mixed model ? (the 12 test subjects being different from the 7 control subjects)

if you put group as a factor in the model, you are testing that the two groups means come from different populations