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Hi Jon, I'm a little confused - is " subject1 - group 1 " the same actual subject as "subject1 - group 2" - this is how you seem to be modelling it? If not, this model is not right, and the correct modelling is a bit trickier. Also, "pos effect time 1" and "pos effect time 2" contrasts reflect postive and negative correlations with time - is this what you mean? Cheers, Eugene -- On 22 October 2011 10:50, Jon Brock <[log in to unmask]> wrote: > 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 > >