You should first test whether there is an interaction between group and covariate. If there is non, then you can keep the same FSGD file but run it with DOSS (different offset, same slope). The "same slope" means that the difference will be the same regardless of the value of the covariate. You will need to make a different contrast. See https://surfer.nmr.mgh.harvard.edu/fswiki/DodsDoss
for more info
On 4/16/17 7:04 AM, Laura Ferrero Montes wrote:
Dear FS team, I would like to make an analysis between a Patients Group and aControl Group. This study is focused on identifying if there are differences in volume between both groups. I want to regress out the effects of gender, age and IQ.
My designed matrix has the following structure: GroupDescriptorFile1 Class PatientMale Class PatientFemale Class ControlMale Class ControlFemale Variables Age IQ Input subject1 PatientMale 25 110 Input subject2 ControlMale 30 90
I was thinking about a Contrast Matrix like this: 0.5 0.5 -0.5 -0.5 0 0 0 0 0 0 0 0 However, looking for some information I discovered that it only compares volume of two groups at the naissance because it is only comparing intercepts. Therefore, how I could make a comparison between volumes of two groups in general? Thank you, Laura
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