The question for BREAKFAST in 1977 was asked for a sub-sample of randomly selected persons age 20 and over; NHIS automatically classifies persons who were selected but did not complete the questions as responding "unknown- " for this variable. Users may choose to use this variable in combination with SUBSRESP77, which reports the person's sub-sample status in 1977.

In 1977 and 1983, respondents could answer "every day," "sometimes," "rarely or never," and "other." In 1985 and 1990, the term "every day" was changed to "almost every day" and the category of "other" was dropped from the survey. However, IPUMS NHIS recodes responses to both "every day" and "almost every day" into one category (recode of "1").

The definition of breakfast changed over time. In 1977, 1985 and 1990, the Field Representative's Manual instructed interviewers not to consider coffee or tea alone as breakfast if such information was volunteered; otherwise the term was respondent defined. In 1983, the term was completely defined by the respondent.