The covariate file should be similar to the 3dttest++ covariate file. From the
help:
-covariates cf = Read file 'cf' that contains covariates values for each dataset
input (in both -setA and -setB; there can only at most one
-covariates option). Format of the file
FIRST LINE --> subject IQ age
LATER LINES --> Elvis 143 42
Fred 85 59
Ethel 109 49
Lucy 133 32
This file format should be compatible with 3dMEMA.
++ The first column contains the labels that must match the dataset
labels stored in the input *.grpincorr.niml files, which are
either the dataset prefixes or whatever you supplied in the
3dSetupGroupInCorr program via '-labels'.
-- If you ran 3dSetupGroupInCorr before this update, its output
.grpincorr.niml file will NOT have dataset labels included.
Such a file cannot be used with -covariates -- Sorry.
++ The later columns contain numbers: the covariate values for each
input dataset.
-- 3dGroupInCorr does not allow voxel-level covariates. If you
need these, you will have to use 3dttest++ on the '-sendall'
output (of individual dataset correlations), which might best
be done using '-batch' mode (cf. far below).
++ The first line contains column headers. The header label for the
first column isn't used for anything. The later header labels are
used in the sub-brick labels sent to AFNI.
