2020 COVID-related NHIS Study Design Changes, Introduction of a Parallel Sample, and COVID-Related Content

The National Center for Health Statistics continued to field the NHIS throughout 2020 with several notable changes to data collection and questionnaire content to accommodate COVID and COVID-related nonresponse.

The National Center for Health Statistics (NCHS) fielded four separate NHIS study designs during the course of 2020:

    1) Normal data collection in quarter 1,
    2) Telephone-only in quarter 2,
    3) Telephone-first in quarters 3 and 4, and
    4) The introduction in August 2020 of a parallel sample.

Below, we describe the study design changes at various points in 2020, describe the parallel sample, and provide an overview of COVID-related content introduced during 2020. For additional information and updates, please refer to the NCHS website on NHIS 2020 data collection efforts. These data are slated to be released sometime in 2021.

Changes to Interviewing Procedures

Between mid-March and July (quarter 2), the NHIS temporarily became a telephone-only survey. While the telephone-only approach was in the field, household response rates dropped from 60% in calendar quarter 1 of 2020 to 42.7% in quarter 2; sample adult and sample child response rates fell from 57.9% to 41.1% and 57.6% to 40.1%, respectively (Dahlhamer et al., 2021). In July, a telephone-first approach was implemented in selected areas, and then rolled out in all areas in September. Under the telephone-first approach, household contacts were still attempted by telephone first, and personal visits were reserved for follow-up on nonresponse, to deliver recruitment materials, and to conduct interviews when telephone numbers were unknown. The telephone-first approach will continue for the foreseeable future.

During the time that NHIS was a telephone-only survey, survey response rates decreased from 60 to 43%. However, with the introduction of the telephone-first design, response rates have increased to 50-60%. Approximately 30% of interviews were conducted in-person in September 2020.

Back to Top

Parallel Sample

To inform weighting and estimation techniques that will be used to produce official 2020 estimates, NCHS chose to introduce a subsample of adults who had previously participated in the NHIS with known representativeness and nearly complete telephone contact information. From August to December 2020, NCHS re-contacted by telephone a parallel sample of roughly 20,000 adult respondents who completed the NHIS in 2019 and were invited to complete the 2020 NHIS questionnaire. Between 50 and 60% of the parallel sample completed the 2020 NHIS questionnaire. The longitudinal data collected on this sample will allow users to evaluate health, health care, and well-being from before and during the pandemic. To free up resources to field the parallel sample, the size of the quarter 3 and 4 samples was reduced by half.

Additional COVID-related content

A set of nearly 30 questions related to COVID were added to the 2020 NHIS sample adult questionnaire starting in quarter 3. The additional questionnaire content can be previewed directly on the NCHS website. Nine COVID-related questions identical to ones fielded to sample adults were also added to the sample child questionnaire.

Table 1 lists the COVID-related questions that were added in quarter 3, 2020, and whether they were available for the sample adult and sample child. Table 2 lists questions added in quarter 3, 2020 that were not specifically COVID-related but may be of interest to researchers evaluating the impact of the pandemic on social support. These questions are only available for Sample Adults. When the additional COVID-related questions are integrated into IPUMS NHIS, Tables 1 and 2 will be updated with links to the IPUMS NHIS variable equivalents.

Back to Top

Table 1. COVID-related questions added in Quarter 3, 2020

Question ID Text Sample Adult Sample Child
CNV.0010.00.04 At any time since the start of the coronavirus pandemic, were you in treatment or supposed to receive treatment for your cancer? X
CNV.0020.00.4 Were any of your treatments for cancer changed, delayed, or cancelled because of the coronavirus pandemic? X
CNV.0030.00.4 As a cancer patient or cancer survivor, you may need OTHER medical care related to your cancer such as lab visits, imaging, monitoring visits, rehabilitation, physical therapy, care for side-effects, or visits with medical specialists. At any time since the start of the coronavirus pandemic, did you need any of this OTHER medical care related to your cancer? X
CNV.0040.00.4 Was any of this OTHER medical care related to your cancer changed, delayed, or cancelled because of the coronavirus pandemic? X
CVD.0020.00.4 Has a doctor or other health professional ever told [you/SAMPLE CHILD'S NAME] that you had or likely had coronavirus or COVID-19? X X
CVD.0030.00.4 Have [you/SAMPLE CHILD'S NAME] ever been tested for coronavirus or COVID-19? X X
CVD.0040.00.4 Did the test find that [you/SAMPLE CHILD'S NAME] had coronavirus or COVID-19? X X
CVD.0050.00.4 How would you describe [your/SAMPLE CHILD'S NAME] coronavirus symptoms when they were at their worst? Would you say no symptoms, mild symptoms, moderate symptoms, or severe symptoms? X X
SDW.0010.00.4 Thinking about your MAIN job or business, are there currently social distancing measures in effect to help keep people apart? X
SDW.0020.00.4 Currently, at your MAIN job or business, how often do you still need to work closer than 6 feet to other people? Would you say all of the time, most of the time, some of the time, or none of the time? X
SDW.0030.00.4 At any time since the start of the coronavirus pandemic, did your MAIN job or business put social distancing measures into effect? X
SDW.0060.00.4 When social distancing measures were in effect, how often did you need to work closer than 6 feet to other people? Would you say all of the time, most of the time, some of the time, or none of the time? X
SDW.0070.00.4 Thinking about the MAIN job you held in the past 12 months, were there ever any social distancing measures in effect while you worked there? That is, were there ever practices in place to help keep people apart? X
SDW.0080.00.4 When social distancing measures were in effect, how often did you still need to work closer than 6 feet to other people? Would you say all of the time, most of the time, some of the time, or none of the time? X
SDW.0090.00.4 When social distancing measures were NOT in effect, how often did you need to work closer than 6 feet to other people? Would you say all of the time, most of the time, some of the time, or none of the time? X
SDW.0100.00.4 How often did you need to work closer than 6 feet to other people? Would you say all of the time, most of the time, some of the time, or none of the time? X
ACC.0010.00.4 Was there any time when [you/SAMPLE CHILD'S NAME] DELAYED getting medical care because of the coronavirus pandemic? X X
ACC.0020.00.4 Was there any time when [you/SAMPLE CHILD'S NAME] needed medical care for something other than coronavirus, but DID NOT GET IT because of the coronavirus pandemic? X X
ACC.0030.00.4 In the past 12 months, have [you/SAMPLE CHILD'S NAME] had an appointment with a doctor, nurse, or other health professional by video or by phone? X X
ACC.0040.00.4 Were any of [your/SAMPLE CHILD'S NAME] appointments done by video or by phone because of reasons related to the coronavirus pandemic? X X
CGR.0010.00.4 Was there any time when you needed care at home from a nurse or other health professional but DID NOT GET IT because of the coronavirus pandemic? X
CGR.0020.00.4 During the past 12 months, did you receive care at home from a friend or family member? X
CGR.0030.00.4 Was there any time when you needed care at home from a friend or family member but DID NOT GET IT because of the coronavirus pandemic? X
CGR.0040.00.4 Did a friend or family member provide some or all of the care that a nurse or other health professional did not provide due to the coronavirus pandemic? X

Back to Top

Table 2. Additional Relevant Questions for Sample Adults Introduced in Quarter 3, 2020

Question ID Text
SOS.0010.00.4 How often do you get the social and emotional support you need? Would you say always, usually, sometimes, rarely, or never?
SOS.0020.00.4 Compared with 12 months ago, would you say that you now receive more social and emotional support, less social and emotional support, or about the same?

Additional Resources

Dahlhamer JM, Bramlett MD, Maitland A, Blumberg SJ. Preliminary Evaluation of Nonresponse Bias Due to the COVID-19 Pandemic on National Health Interview Survey Estimates, April-June 2020. Hyattsville, MD: National Center for Health Statistics. February 2021.

SHADAC. NHIS: Early Release Estimates Show Unchanged Coverage Rates during First Half of 2020, although NCHS Reports Evidence of Nonresponse Bias due to COVID-19. February 15, 2021.

Back to Top