More detail on whether a hospital night was "generated" can be learned from the Field Representative's Manuals, which note that, for each hospitalization, the interviewers should verify the date of entry into the hospital and the number of nights, footnote "date verified," and fill in answers for the remaining hospitalization questions (such as the type of hospital). The Manuals state that "any necessary deletions will be handled when the questionnaires are processed."

For 1969-1981, for each hospitalization episode in the past year, the interviewer initially asked, "When did -- enter the hospital (nursing home)?" and filled in the admission month, date, and year. After collecting the name and address of the institution, the interviewer asked, "How many nights was -- in the hospital (nursing home)?" Three additional questions were asked if the answers were not evident from prior entries: "How many of these -- nights were during the past 12 months?" "How many of these -- nights were in the past 2 weeks?" and "Was -- still in the hospital (nursing home) last Sunday night for this hospitalization (stay)?"

For 1982-1996, for each hospitalization episode in the past year, the interviewer asked, "On what date did -- enter the hospital?" (recording admission month, date, and year) and then immediately asked, "How many nights was -- in the hospital?" In the latter period, the additional questions for clarification were dropped, and there was no reference to nursing home stays. This last change parallels the dropping of follow-up questions about stays in convalescent homes and nursing homes in the initial probe about any hospital stays in the past year. (See HOSPNGHTD for further details.)

For example, as discussed in greater detail for HOSPNGHTD, nights spent in the emergency room, staying with a sick family member, or admission to and release from the hospital on the same date did not count as overnight stays.

After 1997, interviewers did not ask about the dates the individual was hospitalized, nor ask the number of hospital night stays for each hospitalization episode. Rather, respondents were asked a summary question: "Altogether, how many nights were you in the hospital during the past 12 months?" For HOSPNITE, data are based directly on responses to a question, rather than generated by the NCHS, based on information reported to interviewers. Researchers should thus be cautious in combining results from HOSPNITED, for the pre-1997 years and from HOSPNITE, for 1997 forward.

As the 1997 NHIS Survey Description states: