Broadly, people are considered uninsured if they do not have coverage under private health insurance, Medicare, Medicaid, public assistance (through 1996), Children’s Health Insurance Program (CHIP), a state-sponsored or other government-sponsored plan or program, or a military health plan. Because of differences in methodology, question wording, and recall period, estimates from different sources may vary and are not directly comparable. For more information, see: U.S. Census Bureau. Health insurance measurement: Differences by data source. Available from: https://www2.census.gov/programs-surveys/demo/visualizations/p60/257/health_insurance_measurement.pdf.
National Health Interview Survey (NHIS)
In NHIS, uninsured includes people who do not have coverage under private health insurance, Medicare, Medicaid, public assistance (through 1996), CHIP, a state-sponsored health plan, other government-sponsored programs, or a military health plan. People with only Indian Health Service coverage are considered uninsured. Estimates for uninsured are shown only for the population under age 65. Estimates of the percentage of people who are uninsured based on NHIS may differ slightly from those based on the Current Population Survey Annual Social and Economic Supplement or the American Community Survey because of differences in survey questions, recall period, and other aspects of survey methodology.
Survey respondents may be covered by health insurance at the time of interview but may have experienced one or more lapses in coverage during the year before interview. Starting with Health, United States, 2006, NHIS estimates for people with health insurance coverage for all 12 months before interview, for those who were uninsured for any period up to 12 months, and for those who were uninsured for more than 12 months are added as stub variables to selected tables. (Also see Sources and Definitions, Health insurance coverage.)