For 1997 to 1999, those who did not answer the initial question affirmatively are coded NIU (not in universe) for follow-up questions on insurance characteristics. Beginning in 2000, the response "no insurance" was included as a valid response to the initial question. Thus, for 2000 forward, the universe for follow-up questions on insurance coverage type and details was "all persons" (including those with an affirmative response to HINONE or "no insurance").

In essence, for 1976 to 1996, Medicaid was defined as a health insurance program that provides medical assistance to persons in need. The Field Representative's Manuals for 1997 forward defined Medicaid as "a medical assistance program that provides health care coverage to low income and disabled persons. The Medicaid program is a joint federal-state program which is administered by the States."

1976For 1976, HIPUBCOV indicates Medicaid coverage or welfare received, with the information ascertained indirectly from responses about the person's reasons for not having private insurance or Medicare. Such indirect measurement of public coverage tends to be less accurate than direct questions about coverage, with a bias towards fewer affirmative responses for public coverage.

• Which of these statements (Hand card) best describes why -- is not covered by any (private) health insurance plan? Any other reasons? Response categories: Care received through Medicaid or Welfare

• Does anyone in the family now receive assistance through the "Aid to Families with Dependent Children" program, sometimes called "AFDC" or "ADC"?

• Does anyone in the family now receive the "Supplemental Security Income" or "SSI"?

• Does anyone in the family now have a Medicaid {or (name)} card?

In addition, the following questions were asked in these survey years:
1980

• Which of those statements describes why -- is not covered by any health insurance plan? Any other reason? Response categories: Care received through Medicaid or Welfare.

• Is anyone in the family now covered by any other public assistance program that pays for health care?

• In (month), was anyone in the family covered by Medicaid or (local name)?

• Did -- receive Aid to Families with Dependent Children, sometimes called AFDC or ADC, or some other type of assistance payments in (month)?

• In (month), was anyone in the family covered by any OTHER public assistance program (other than Medicaid) that pays for health care?

• In (month), did anyone in the family receive public assistance or welfare payments from the state or local welfare office?

• In (month), was anyone in the family covered by Medicaid?

• In (month), was anyone in the family covered by any OTHER public assistance program (other than Medicaid) that pays for health care? Do NOT include use of public or free clinics if that is the only source of care.

• In (month), did anyone in the family receive public assistance or welfare payments from the state or local welfare office?

• In (month), did anyone in the family receive Supplemental Security Income or SSI?

• Did -- receive Aid to Families with Dependent Children, sometimes called AFDC or ADC, or some other type of assistance payments in (month)?

• Private health insurance (2004 forward)

• Private health insurance plan from employer or workplace (1997-2003)

• Private health insurance plan purchased directly (1997-2003)

• Private health insurance plan through a State or local government program or community program (1998-2003)

• Medicare (1997 forward)

• Medi-Gap (1997 forward)

• Medicaid (1997 forward)

• CHIP (Children's Health Insurance Program) (1999 forward)

• Military Health Care/VA (1997-2003)

• Military Health Care (CHAMPUS/TRICARE/CHAMP-VA) (1997 forward)

• Indian Health Service (1997 forward)

• State-sponsored health plan (1997 forward)

• Other government program (1997 forward)

• Single Service Plan (e.g., dental, vision, prescriptions) (1999 forward)

• No coverage of any type (2000 forward)

Respondents could pick more than one type of insurance, and interviewers were instructed to mark all that applied.

During the course of data editing, the NCHS discovered many errors in the responses to questions about insurance coverage. This might be shown, for example, by a mismatch between the verbatim name of an insurance plan and the type of insurance coverage the person selected from categories on a flashcard. Beginning in 1997, plan names were used to back-edit responses to verify the accuracy of insurance type. (See the variable description for HINOTCOVE for a description of this back-editing process.)