subjectCenteringTransform
is a transformation that can
be applied to a matrix of data. the resulting matrix have means
that are centered on the grand mean, subject-wise c05superb.
subjectCenteringTransform(dta, variables)
a data.frame of the same form as dta with the variables transformed.
This function is useful when passed to the argument preprocessfct
of superb()
where it performs a modification of the data matrix.