The universe of HINOMISS is slightly different from the definition of uninsured set in the NCHS publication Health, United States. More specifically, respondents with Indian Health Service coverage are not in universe for HINOMISS (i.e., they are considered to have coverage) but are considered uninsured by the standard set in Health, United States. Users should see HINOTCOVE, which matches the definition of Health, United States, for more details on how uninsured is defined. In both instances, persons with only single service plans are considered to be without health insurance coverage.

For HINOMISS, respondents are defined as not having health insurance coverage if they did not have coverage through Medicare (HIMCAREE), Medicaid (HIMCAIDE), Private health insurance (HIPRIVATEE), Children's Health Insurance Program (HICHIPE), Military related health care (HIMILITE), state-sponsored health plan (HISTATEE), other public program (HIOTHGOVE), and Indian Health Service (HIHSE).

The universe for HINOMISS is determined using the recoded variables for health insurance coverage. During the course of data editing, NCHS discovered many errors in the responses to questions about insurance coverage and created a series of recoded insurance variables to correct for these errors. See the HIPRIVATEE variable description for a more detailed description of this back-editing process.