 |
 |
Dear FSL experts,
We are currently working on running structural analyses through FIRST. Our sample is within group (all PTSD patients) and our two continuous variables of interest are measures of depressive severity (GDS) and PTSD symptamatology (CAPS). We also have two nuisance variables: age and ICV. Specifically, we would like to look at the interaction of the two behavioral measures (i.e. multiple regression of GDS x CAPS) while controlling for age and ICV, in one model. Our investigation then, is to see how the interaction of these behavioral measures predicts subcortical volume and/or shape. We are having trouble, however, figuring out how to set up the design matrix, contrast codes and F-tests. Any insights would be greatly appreciated!
Thank you,
Lindsay Knight