In this variable, current smokers are divided into "every day" smokers or "some days" smokers. The process to classify respondents into these categories changed slightly between 1991 and 1992 forward. In 1991, ever smokers were asked if they smoke now; respondents who said "yes" were asked if they smoked "every day" or "some days. Respondents who answered "no" were asked, "Do you smoke some days or not at all?" This additional follow-up resulted in the classification of persons as "someday smokers" who would otherwise have been considered former smokers, since they initially said that they did not smoke now.

In 1992, questions on smoking status were included in two sections of the survey; in the Cancer Control section, the same three questions from in the 1991 questionnaire were used; in the Cancer Epidemiology section, just two questions were used: "Have you smoked at least 100 cigarettes during your entire life?" If yes, "Do you NOW smoke cigarettes every day, some days, or not at all?" Use of both sets of questions allowed for estimation of the impact of the question change on population prevalence. The revised current smoking status question was estimated to have resulted in an increase in smoking prevalence of about 1 percent-- a result occurring mainly from capturing smoking among persons who would otherwise have been classified as nonsmokers with the original question.

This version of the question was used from 1992 forward. A small additional change occurred in 1997 when, the question for the number of days on which the respondent smoked changed from asking on how many of the past 30 days did the respondent "smoke cigarettes" to "a cigarette."

These include:

• SMOKESTATUS1 "never," "current," "former," "former regular smoker," "former occasional smoker," "unknown," and unknown if ever smoked 100 cigarettes," and "smoked 100 cigarettes, unknown if currently smoke."

• SMOKESTATUS2 current smoker, every day current smoker, some day current smoker, current smoker--unknown frequency of smoking also indicates former smoker, never smoked and "has smoked, current smoking status unknown."