The function cv.trans.psa takes a covariate data frame and replaces each
categorical covariate of n >=3 levels with n new binary covariate columns,
one for each level. Transforms covariate dataframe for use with the function
cv.bal.psa.
cv.trans.psa(covariates, fcol = NULL)A dataframe of covariates, presumably some factors.
An optional vector containing the factor columns in the covariate
data frame. In NULL (default) routine to identify factors internally.
James E. Helmreich James.Helmreich@Marist.edu
Robert M. Pruzek RMPruzek@yahoo.com
KuangNan Xiong harryxkn@yahoo.com
Jason Bryer jason@bryer.org
NOTE: This function originated in the PSAgraphics package. It has been
adapted here for the multilevelPSA package.