Return the special character(s) of the Cox model, e.g. used to indicate the strata variables.
coxSpecial(object)# S3 method for coxph
coxSpecial(object)
# S3 method for cph
coxSpecial(object)
# S3 method for phreg
coxSpecial(object)
The fitted Cox regression model object either
obtained with coxph
(survival package), cph
(rms package), or phreg
(mets package).
Must return a list with at least one element strata indicating the character in the formula marking the variable(s) defining the strata.