afni.nimh.nih.gov

Hi Adam,

If you wish to do an ANCOVA, you might find 3dttest++ or 3dMVM easier.

If you are absolutely determined to use 3dRegAna, you will need to "dummy code" your task variable. You can see Example 4 in the 3dRegAna white paper for guidance. If you have repeated-measures (i.e. everyone in the experiment did all 4 tasks) then things get even more interesting...

It's also possible that I missed your question, so feel free to clarify if so.

Peter