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."

When asking the question associated with CIGADYMO, the 1997-2000 Manuals instructed interviewers to "[a]lways probe for an exact number" and to assist respondents in making an estimate if they reported a range or interval. The 1997-2000 Manuals also instructed interviewers, "If asked, explain that 'past 30 days' includes up to the day before the interview and not the day of the interview."

"Some day" smokers who smoked 1+ days or an unknown number of days during the past 30 days (according to CIGDAYMO) were asked the follow-up question, "On the average, when you smoked during the past 30 days, about how many cigarettes did you smoke a day?" Responses to this question are reported in CIGSDAY2.

"Every day" smokers (IPUMS NHIS code 3 in SMOKFREQNOW) were asked, "On the average, how many cigarettes do you now smoke a day?" (CIGSDAY1). The variable CIGSDAY combines responses given to the questions associated with CIGSDAY1 and CIGSDAY2, reporting the average number of cigarettes smoked per day for "current smokers" (i.e., all "every day" smokers and "some day" smokers who smoked 1+ days or an unknown number of days in the past 30 days). The universe for CIGSDAY also includes (in 1997-2003) respondents whose current smoking status was unknown (IPUMS NHIS code 7-9 in SMOKFREQNOW). Respondents whose smoking status was unknown were all coded as "Unknown-not ascertained" in CIGSDAY (IPUMS NHIS code 98).

CIGSDAY also reports the average number of cigarettes smoked per day for persons age 17+ who were current smokers (1970) and persons age 20+ who were part of a 1/3 subsample and who were current smokers (1976-1977).