There are two ways to do a paired-t. The easiest, I think, is to use the --paired-t option to mris_preproc. The other option is to set it up in the fsgd file, but that's more complicated and less flexible. What do you mean by "group"? A class in the fsgd gets it's on mean regressor and possibly slope regressor. Eg, if you have two groups: male and female, and you want to analyze taking into account handedness, then you'd have 4 classes: ML, MR, FL, FR.

doug

Reschke, Cole wrote:

All-

I am looking to run freesurfer group analysis on a longitudinal study, examining the changes between baseline and follow-up. I would like to set up a paired t-test, yet I am still in need of some assistance creating my FSGD file and my design matrix. I have read the GroupAnalysis wiki page, and did not see anything regarding t-tests. Also, is "Class" is equivalent to "Group" in the FSGD file?

I have been using your sample GroupDescriptorFile to create my own, and pasted an excerpt below (my edits are in red and underlined).

GroupDescriptorFile 1

Title MyTitle

Class bsl plus blue

Class flp circle green

Variables Age Gender

Input subjid1 bsl 20 M

Input subjid1 flp 20 M

DefaultVariable Age

Cole Reschke

Data Manager, PET Center

Banner Alzheimer Institute

Banner Good Samaritan Medical Center

Phone: (602) 239-4868

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