ttest problem

Hi, I want to run ttest with my data. And it says that the number of voxel is different. (show in attachment) . I know it is because for different data have different number of voxel, but how can I solve this problem. Can someone give me a hint.


You can check the voxelsize and matrix dimensions of one or more datasets with:

3dinfo -ad3 -n4 -prefix DSET_OR_LIST_OF_DSETS

You can also ask if two datasets have the same grid (a more detailed constraint) with:

3dinfo -same_all_grid LIST_OF_DSETS

Calculations across datasets often require having the same grid. There are multiple ways to put a dataset onto another grid, but it is correct to know what your expectations are for it and how it got to its current place—you want to use a grid transformation that is appropriate for the data. I guess the first question is, why don’t the datasets in your 3dttest++ command sit on the same grid? How were they processed? Are they actually in the same “space” (e.g., they were all aligned to a single template, and if you view them in the AFNI GUI, they overlap correctly), but have a different grid?