Hi,
I apologise in advance as this subject seems to be getting a lot of air time at the moment
(on this and other lists) but as a relative novice I am still a little confused about
how best to proceed.
A number of earlier emails have included questions related to a 2x2 repeated measures design
(with groups (e.g. controls vs patients) as a between subjects factor and time
(e.g pre and post) as the within subjects factor. I have attached what I believe to be the
correct design matrix to probe the main effects of group and time and the group x time
interaction (inputs are lower level feat directories, and the subjects are entered as:
Subject1-Group1-Scan1
Subject2-Group1-Scan1
Subject3-Group1-Scan1
Subject4-Group1-Scan1
Subject1-Group2-Scan1
Subject2-Group2-Scan1
Subject3-Group2-Scan1
Subject4-Group2-Scan1
Subject1-Group1-Scan2
Subject2-Group1-Scan2
Subject3-Group1-Scan2
Subject4-Group1-Scan2
Subject1-Group2-Scan2
Subject2-Group2-Scan2
Subject3-Group2-Scan2
Subject4-Group2-Scan2
My naive questions are:
1) Does the attached design correctly probe the above questions?
2) If so, are there any caveats that need to be noted when reporting the
results using this sort of approach?
3) If not the above then what is the optimum way to ask these questions with this type
of design? A big ask I know but perhaps an image of the required design matrix/matrices
as an attachment to list or added to the FSL website.
Apologies again.
Jon
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