afni.nimh.nih.gov

> Should I still treat this variable as between subject or as a quantitative variable when I have a full complement of subjects?

A variable is between-subjects if it varies across subjects but not within, so 'symsev' is between-subjects by that definition (otherwise you would have to use 3dLME). The option -bsVars is meant to declare any between-subjects variables (factors as well as quantitative covariates).

Gang