Dear Gang,
Thank you very much for your reply. The covariates of no interest are between-subjects quantitative variables -- for this, then I would use 3dMVM.
But in the further analysis, I might want to pursue to add quantitative variables that are within-subjects (associated with each of w/s-condition). This would require 3dLME in the end? If it is within-subjects variable, the qVarCenter should specify the centering value considering all conditions across all subjects? So when the model is being tested, data will be all scaled (subtracted by qVarcenter value)?
Thanks a lot for your help!
Michelle.