I am analysing repeated-measures data in a 3x3 design (i.e. two factors, each with 3 levels). I am using a flexible-factorial model and have done the steps of "Specify 2nd-level" and "Estimate". When specifying the model, I included the 2 main effects & their interaction (hence, there are 15 columns: A1, A2, A3, B1, B2, B3, A1B1, A1B2, A1B3, A2B1, A2B2, A2B3, A3B1, A3B2, A3B3). 

Now I am at the "Results" step and am prompted to enter contrast matrices. I have searched through the forums but have not found an example of how to test a 3x3 design. I have constructed the following contrast matrices based on my understanding so far, and would like to check with you if they are correct:

Main effect of Factor A:

1 -1 0 0 0 0 1/3 1/3 1/3 -1/3 -1/3 -1/3 0 0 0

0 1 -1 0 0 0 0 0 0 1/3 1/3 1/3 -1/3 -1/3 -1/3

Main effect of Factor B:

0 0 0 1 -1 0 1/3 -1/3 0 1/3 -1/3 0 1/3 -1/3 0

0 0 0 0 1 -1 0 1/3 -1/3 0 1/3 -1/3 0 1/3 -1/3

 

3x3 Interaction (A*B):

0 0 0 0 0 0 1 -1 0 -1 1 0 0 0 0

0 0 0 0 0 0 0 1 -1 0 -1 1 0 0 0

0 0 0 0 0 0 0 0 0 1 -1 0 -1 1 0

0 0 0 0 0 0 0 0 0 0 1 -1 0 -1 1

When there are multiple rows in a contrast matrix, does that mean multiple tests are being conducted to test that effect? Does SPM automatically take care of the multiple comparison problem in this case?

Any advice would be greatly appreciated. Thank you very much in advance!

Kind regards,

Judy

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