Throughout this period prior to 1982, interviewers asked,"During the past 12 months, about how many times did - see or talk to a medical doctor?," adding, as needed, "Do not count doctors seen while a patient in a hospital. Include the - visits you already told me about."

First, the question added the word "assistant" (i.e., "see or talk to a medical doctor or assistant").

Second, the wording for 1982 forward indicated that the respondent should include times when other family members talked to a doctor/assistant about a child, as well as times when the child saw the doctor/assistant directly: "about how many times did [-/anyone] see or talk to a medical doctor or assistant [about -]?" In other words, from 1969 to 1981, when this question was asked for children, the interviewer asked how many times the child saw or talked to a doctor, whereas from 1982 to 1996, the question asked how many times the child or anyone talked to a doctor/assistant about the child.

The NHIS document Questionnaires from the National Health Interview Survey, 1980-84: Programs and Collection Procedures: Series 1, No. 24 also notes that while the conceptual definition of a doctor did not change, the survey text made the definition more explicit to survey respondents beginning in 1982. Initially, the definition of doctor was not given anywhere in the survey text. For 1982-1996, a survey question on doctor visits in the past 2 weeks (placed prior to DVI2 in the questionnaire) stated, "Include all types of doctors, such as dermatologists, psychiatrists, and ophthalmologists, as well as general practitioners and osteopaths."

In the original public use files, for the earlier period, a code of "0" for DV12 indicates either "None" or "unknown" in the public use files; for the later period, "0" means "None" only (with "unknown" receiving a code of "998" in the NHIS public use files). In IHIS, supplemental programming imposes a consistent meaning of "None" on the zero code for DV12. For IHIS, the meaning of ambiguous cases (i.e., those coded "0" in DV12 in the public use files for 1969-81) was determined by the value of a separate variable that specified whether the number of doctor visits in the past year was known or unknown.

VISITYRNO provides answers to the following question:

Along with the change in universe (from all persons for DV12 to sample adults and sample children for VISITYRNO), VISITYRNO imposed many restrictions on where and how the health professional was contacted, which limits comparability of the data before and after 1997. Furthermore, as mentioned above, responses to VISITYRNO were grouped into 10 categories (from "No visits" to "16 or more visits"), which users may wish to replicate for DV12.