Steps:
1) For each subject, create a brain dataset with value of Y for that subject at each voxel. You may use 3dcalc on a group mask to achieve that.
2) For each subject, create a brain dataset with value of X * B for that subject at each voxel. You may use 3dcalc on B to achieve that.
3) Use the results from 1) as input for 3dttest++, and specify the covariate file with the following three columns as covariates: X, B, and X * B from 2).
Gang
Edited 1 time(s). Last edit at 06/19/2014 02:35PM by Gang.