twoStepTransform, is a transformation that can be applied to a matrix of data. The resulting matrix is both subject-centered and bias corrected, a technique called the CM technique b12,c05,m08superb
twoStepTransform(dta, variables)a data.frame containing the data in wide format;
a vector of column names on which the transformation will be applied. the remaining columns will be left unchanged
a data.frame of the same form as dta with the variables transformed.