NULL.parse regression components (either false positive rate or etiology regression)
for fitting npLCM; Only use this when formula is not NULL.
parse_nplcm_reg(form, data_nplcm, silent = TRUE)TRUE for doing regression; FALSE otherwise.
regression formula
data object for nplcm(); may contain covariates X;
must have case-control status Y.
Default is TRUE for no message about covariates;
FALSE otherwise.