definition of the label "niu"

Hello. I could not find the for the variable Non-mlanoma skin cancer= “cnskna.”

Should I drop all data related to this label before conducting my analysis on a very smaller sample?

Thanks

The “NIU” value label indicates an individual record is “not in universe”. This means that the question was not asked to this person. In general, yes, it is a good idea to drop all NIU observations when performing analysis on a particular variable.