The 1997 forward 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 CIGSDAY1, the 1997 forward 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 forward Manuals also stated, "If the response is given in packs rather than the number of cigarettes, multiply the number of packs by 20, verify the result with the Sample Adult (some brands have 25 cigarettes per pack), and enter the number of cigarettes per day."

Respondents who had ever smoked 100 cigarettes (SMOKEV), who were "Some day" smokers (IPUMS NHIS code 2 in SMOKFREQNOW), and who smoked 1+ days or an unknown number of days during the past 30 days (according to CIGDAYMO) were asked, "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.

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 (IHIS code 7-9 in SMOKFREQNOW). Respondents whose smoking status was unknown were all coded as "Unknown-not ascertained" in CIGSDAY (IHIS 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).