In 1970 respondents were asked, "About how old was [person] when he first started smoking cigarettes fairly regularly?" Before receiving the question associated with SMOKEFAGE, respondents were asked whether they had ever smoked 100 cigarettes (SMOKEV) and whether they currently smoked. Respondents who reported having ever smoked 100 cigarettes or for whom it was unknown whether they had ever smoked 100 cigarettes and who either reported that they did not currently smoke or had an unknown answer for whether they currently smoked were asked the follow-up question, "How long has it been since [person] smoked cigarettes fairly regularly?" Only respondents who did not report that they never smoked regularly to this question were asked the question associated with SMOKAGEREG. Also included in the universe for SMOKAGEREG in 1970 are respondents who reported having ever smoked 100 cigarettes (SMOKEV) and who indicated that they currently smoked.

For 1997 forward respondents were asked, "How old were you when you FIRST started to smoke fairly regularly?" This question was asked of sample adults age 18+ who reported having ever smoked 100 cigarettes (SMOKEV).

The 1970 Field Representative's Manual instructed interviewers to "[e]xclude marijuana, a type of wild tobacco, (also called "pot" or "grass')" when accepting responses to the smoking-related questions.

The 1997-2000 Field Representative's Manuals stated, "The questions in this section concern cigarette smoking only. Accept whatever the Sample Adult reports, except if it is volunteered that he/she smoked a pipe, cigars of any kind, marijuana, hashish, 'crack', or the like." The Manuals for 2001 forward define a cigarette as "anything the respondent reports except cigars or any kind of marijuana."

The 1970 Manual defined "fairly regularly" as "smoking one or more cigarettes on three or more consecutive days." The Field Representative's Manuals for 1997 forward stated that "first started to smoke fairly regularly" and "smoking regularly" are respondent defined. If respondents asked what it meant, the Manuals for 1997 forward instructed interviewers say, "'It's whatever you consider as first starting to smoke fairly regularly.'"

In 1970, the Manual instructed that "if a person does not remember his exact age when he first started smoking cigarettes regularly, obtain his best estimate. As an aid, subtract the number of years from his present age. A person may also be able to relate age started smoking to his high school or college attendance or Armed Forces service."

The Manuals for 1997-2000 instructed interviewers to "Always probe for an exact age" and to assist respondents in making an estimate if they reported a range or interval.