help > RE: 2x3 Mixed Design ANOVA
Oct 18, 2018  06:10 PM | Andrew Zalesky
RE: 2x3 Mixed Design ANOVA
Hi Ana,

I forgot that your design is a repeated measures design. If you are only interested in the group effect, a repeated measures design is not necessary. You can either run a between-group t-test for each time point or first average your data across time points and perform a single t-test of the between-group difference.

What you might be interested in testing for the current repeated measures design is the interaction between group and time. Assuming that the first 8 subjects are group 1 and the last 8 subjects are group 2, the design matrix would look like this:


 1 1
 2 2
 4 4
 1 1
 2 2
 4 4
 1 -1
 2 -2
 4 -4
 1 -1
 2 -2
 4 -4

Once again, you will need to add additional columns (one for each subject) to model within-subject effects.





Originally posted by Ana Coelho:
Hi Dr. Zalesky,

When I add one column with the two groups encoded as 0/1, I got the warning for rank deficiency.
Why this is happening? Is related with the data or the design matrix?


Thanks in advance!
Ana

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RE: 2x3 Mixed Design ANOVA
Andrew Zalesky Oct 18, 2018
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