What does "coxphw undefined columns selected" mean?

edit

The error message "coxphw undefined columns selected" typically indicates that there is an issue with the input data for the coxphw function in R. Specifically, it suggests that the columns selected for the analysis are undefined or do not exist in the data frame. This error may occur if the column names are misspelled or if the data is not formatted correctly. It is important to review the code and ensure that the input data matches the specifications required for the coxphw function.