I've been running into an issue while trying to analyze a dataset. I am looking at fcMRI data for two groups who differ significantly in their ages and am using age as a covariate. I can get the basic model (without GLTs) to run without errors and I can get the model to run with GLTs if I don't include the covariate in gltCode. However, any time I include the covariate in a GLT (as in the script below), the model test fails. I suspect it has something to do with the large discrepancy in variance between the two groups (group1 ages 18-22; group2 ages 18-50ish). Any help would be appreciated as I've tried everything I can think of and nothing has worked so far.
Script as follows:
3dMVM \
-prefix ACC.2GROUP_wAGE -jobs 24 \
-mask avg152.1x1x1.wm.exclusion.mask+tlrc \
-bsVars 'GROUP+age' -qVars 'age' \
-num_glt 1 \
-gltLabel 1 MRNvsPSU -gltCode 1 'GROUP : 1*MRN -1*PSU age :' \
-dataTable \
Subj age GROUP InputFile \
subject01 -3.233 Group1 dx0.subject01.RST.ROI.ACC.CORR.Zscore+tlrc \
subject02 -3.233 Group1 dx0.subject02.RST.ROI.ACC.CORR.Zscore+tlrc \
subject03 -3.233 Group1 dx0.subject03.RST.ROI.ACC.CORR.Zscore+tlrc \
subject04 -3.233 Group1 dx0.subject04.RST.ROI.ACC.CORR.Zscore+tlrc \
subject05 -3.233 Group1 dx0.subject05.RST.ROI.ACC.CORR.Zscore+tlrc \
subject06 -2.233 Group1 dx0.subject06.RST.ROI.ACC.CORR.Zscore+tlrc \
subject07 -2.233 Group1 dx0.subject07.RST.ROI.ACC.CORR.Zscore+tlrc \
subject08 -2.233 Group1 dx0.subject08.RST.ROI.ACC.CORR.Zscore+tlrc \
subject09 -2.233 Group1 dx0.subject09.RST.ROI.ACC.CORR.Zscore+tlrc \
subject10 -2.233 Group1 dx0.subject10.RST.ROI.ACC.CORR.Zscore+tlrc \
...
subject51 1.766 Group2 dx1.subject51.RST.ROI.ACC.CORR.Zscore+tlrc \
subject52 8.766 Group2 dx1.subject52.RST.ROI.ACC.CORR.Zscore+tlrc \
subject53 -2.23 Group2 dx1.subject53.RST.ROI.ACC.CORR.Zscore+tlrc \
subject54 1.766 Group2 dx1.subject54.RST.ROI.ACC.CORR.Zscore+tlrc \
subject55 -1.233 Group2 dx1.subject55.RST.ROI.ACC.CORR.Zscore+tlrc \
subject56 0.766 Group2 dx1.subject56.RST.ROI.ACC.CORR.Zscore+tlrc \
subject57 3.766 Group2 dx1.subject57.RST.ROI.ACC.CORR.Zscore+tlrc \
subject58 2.766 Group2 dx1.subject58.RST.ROI.ACC.CORR.Zscore+tlrc \
subject59 -3.233 Group2 dx1.subject59.RST.ROI.ACC.CORR.Zscore+tlrc \
subject60 -2.233 Group2 dx1.subject60.RST.ROI.ACC.CORR.Zscore+tlrc
