The terms regular, king size and extra long were respondent defined. The Field Representative's Manual noted that if a person smoked more than one type, the interviewer should indicate the length the person usually smoked or preferred.

In the 1970 survey, a respondent representing the family (a proxy) could answer the question associated with CIGLENGTH for all other family members over age 17. As self-report is typically more accurate than proxy report, researchers may want to indicate this caveat when analyzing the data or interpreting results.