 |
 |
Dear SPMers, I have a quick contrast/model question and would be grateful for feedback. I have a fMRI design where I have 3 conditions (a-c) with 3 matched controls (d-f), with each of the 6 conditions run in different sessions. I know this was an horrendous design, but the data is collected and I actually have some great results. The design is sparse. I cannot model the 6 conditions in one model as the TR is different for each condition/control pairing (a/d; b/e; c/f… Note that each volume itself has identical parameters [TA of 4 seconds] while the time between volumes differed). My question is pretty basic–I want to compare the key effect for different control conditions (e.g., control d against control f). Is it legitimate to just take the beta images for the different conditions and compare them at the second level? Even if the TR differs by condition? Thanks very much Christopher