The NHANES program suspended field operations in March 2020 due to the coronavirus disease 2019 (COVID-19) pandemic. As a result, data collection for the NHANES 2019-2020 cycle was not completed and the collected data are not nationally representative. Therefore, data collected from 2019 to March 2020 were combined with data from the NHANES 2017-2018 cycle to form a nationally representative sample of NHANES 2017-March 2020 pre-pandemic data. These data are available to the public. Please refer to the Analytic Notes section for more details on the use of the data.
The Health Insurance questionnaire (variable name prefix HIQ) provides respondent-level interview data on insurance coverage, type of insurance coverage, coverage of prescription drugs, and uninsured status during the past 12 months.
All participants in the NHANES 2017-March 2020 pre-pandemic sample are included in this dataset.
Interview Setting and Mode of Administration
The questionnaire was asked, in the home, by trained interviewers using Computer-Assisted Personal Interview (CAPI) system. A proxy provided information for survey participants who were under 16 years of age and for individuals who could not answer the questions themselves. The respondent selected the language of interview (English or Spanish) or requested that an interpreter be used. Hand cards, showing response choices or information that survey participants needed to answer the questions, were used for some questions. The hand cards were printed in English, Spanish, Mandarin Chinese (both traditional and simplified), Korean, and Vietnamese. The interviewer directed the respondent to the appropriate hand card during the interview. When necessary, the interviewer further assisted the respondent by reading the response choices listed on the hand cards.
The NHANES 2017-2018 and 2019-2020 questionnaires are available on the NHANES website.
Quality Assurance & Quality Control
The CAPI system is programmed with built-in consistency checks to reduce data entry errors. CAPI also uses online help screens to assist interviewers in defining key terms used in the questionnaire.
After collection, interview data were reviewed by the NHANES field office staff for accuracy and completeness of selected items. The interviewers were required to audio-record interviews and the recorded interviews were reviewed by NCHS staff and interviewer supervisors.
Data Processing and Editing
Frequency counts were checked, “skip” patterns were verified, and the reasonableness of question responses was reviewed. Edits were made to some variables to ensure the completeness, consistency, and analytic usefulness of the data. Edits were also made, when necessary, to address data disclosure concerns.
For the 2019-20 survey cycle, the question HIQ031 was changed to HIQ032 and the response category “Single Service Plan” was dropped. To make 2017-18 data compatible to 2019-20 data, respondents who responded “Yes” to HIQ011 and reported only a “Single Service Plan” for HIQ031, were recoded to “No” for HIQ011. To reduce the risk of disclosure, responses of “Military Health Care” and “Indian Health Services” for kind of health care coverage (HQ031/HIQ032) were recoded to “Other Government Program”.
The COVID-19 pandemic required suspension of NHANES 2019-2020 field operations in March 2020 after data were collected in 18 of the 30 survey locations in the 2019-2020 sample. Because the collected data were not nationally representative, these data were combined with data from the previous cycle (2017-2018) to create a 2017-March 2020 pre-pandemic data file. A special weighting process was applied to the 2017-March 2020 pre-pandemic data file. The resulting sample weights in the demographic data file should be used to calculate estimates from the combined cycles. These sample weights are not appropriate for independent analyses of the 2019-2020 data and will not yield nationally representative results for either the 2017-2018 data alone or the 2019-March 2020 data alone. Please refer to the NHANES website for additional information for the NHANES 2017-March 2020 pre-pandemic data, and for the previous 2017-2018 public use data file with specific weights for that 2-year cycle.
Since the questionnaire was asked during the household interview, the interview sample weights should be used in the analysis. However, if the data is joined with data from the Mobile Exam Center (MEC), the MEC sample weights should be used.