Codes and Frequencies
For sample adults and sample children, HIMCAIDE indicates whether the person currently has health insurance coverage through Medicaid. Prior to 2019, this variable was available for all persons.
Medicaid pays for medical assistance to low-income families with dependent children and to aged, blind, or permanently and totally disabled individuals with incomes insufficient to meet the costs of medical services.
The program became law in 1965. Medicaid is administered by state agencies and is jointly funded by the federal, state, and, sometimes, local governments. Eligibility requirements for this means-tested program vary across states. Most recipients of public welfare income programs such as TANF (Temporary Assistance to Needy Families) and SSI (Supplemental Security Income) are eligible for Medicaid coverage. In some states, other persons qualify, such as needy unemployed persons who have children and who are not receiving cash assistance, and medically needy persons whose income and assets are too low to cover their medical costs. Many Medicaid recipients are inmates of medical institutions, such as low-income elderly persons in nursing homes. Such institutionalized persons are not included in the NHIS sample, which covers the civilian non-institutionalized population of the United States.
The Field Representative's Manual for 1997-2018 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."
As the Manuals noted, the name for the Medicaid program varies across states. Interviewers were supplied with cards listing "State Names for Medicaid, CHIP, State-/Local-Sponsored, and Other Health Insurance Programs" in their state.
These linked broad categories of insurance that were studied in the survey to recognizable public health insurance program names. For example, in 1999, the California Medicaid program was called the "Medi-Cal" or "Medi-Cal Managed Care" or "The Two-Plan Model."
HIMCAIDE is a recoded variable created by the National Center for Health Statistics (NCHS) and was included in the original NHIS public use data. HIMCAIDE, like other recoded health insurance variables in these data, is based on responses to a series of questions and by editing carried out by the NCHS.
Data Collection Process
In the survey for 1997 forward, interviewers first asked, "Are you covered by health insurance or some other kind of health care plan?" Respondents were instructed to "Include health insurance obtained through employment or purchased directly as well as government programs like Medicare and Medicaid that provide medical care or help pay medical bills." In 1997-2003 the survey form instructed interviewers to only read the preceding statement "if necessary."
Individuals who had an affirmative response to the preceding question were asked, "What kind of health insurance or health care coverage do you have?" Respondents selected the appropriate response from a card listing various types of insurance coverage.
- 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) (1997-2018)
- Military related health care: TRICARE (CHAMPUS)/VA health care/CHAMP-VA (2019 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) (1999-2018)
- 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.
Instruction regarding single service plans changed over time.
Respondents were consistently instructed to exclude private plans that "only provide extra cash while hospitalized." In 1997-1998 respondents were also instructed to "EXCLUDE private plans that ... pay for only one type of service (nursing home care, accidents, or dental care)." Between 1999 and 2018, "Single Service Plan" was added as a possible response, and, consequently, the instructions were changed to read, "INCLUDE those [private plans] that pay for only one type of service (nursing home care, accidents, or dental care)." Beginning in 2019, respondents were asked three separate questions to determine if they had single service plans for dental services, vision services, and/or prescriptions.
Follow-up questions collected information about the names of coverage plans and confirmed the lack of any type of coverage for the uninsured.
In follow-up questions, interviewers recorded the names of up to four private health insurance plans. If the person was reported as covered by CHIP (beginning in 2000), by a state-sponsored health plan, or by another public program (other than Medicaid) that paid for health care, the interviewer recorded the name of that plan. The placement and wording of these questions about the names of specific government health care plans varied across years.
For persons initially reported as not having health care coverage of any kind, interviewers asked whether the person had Medicare coverage, Medicaid coverage, coverage via a Medicaid program or non-Medicaid state-sponsored health insurance program with the appropriate name for the state, CHAMPUS or CHAMPVA coverage, or any private insurance. For those who acknowledged any such coverage, the interviewer repeated the series of questions mentioned above to determine the specific type of coverage.
During the course of data editing, the NCHS discovered many errors in the responses to questions about insurance coverage. Often, respondents misclassified the type of insurance they had.
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 the categories on the card.
Accordingly, the NCHS created a series of recoded insurance variables. For these recoded insurance variables, such as HIMCAIDE, the data are back-edited, taking into account such factors as the proper classification of the verbatim names of insurance plans and responses to questions about why insurance coverage had stopped. The NCHS strongly advises analysts to use these recoded insurance variables as a more reliable source of information about the types of insurance coverage than is provided by respondents' original and unedited answers about their insurance type.
In addition to HIMCAIDE, IPUMS NHIS contains the following recoded insurance variables: HICHIPE (Covered by Children's Health Insurance Program: Recode); HIPRIVATEE (Covered by private health insurance: Recode); HIMILITE (Covered by military health insurance: Recode); HIHSE (Covered by Indian Health Service: Recode); HIMCAREE (Covered by Medicare: Recode); HISTATEE (Covered by other state-sponsored health plan: Recode); HIOTHGOVE (Covered by other government program: Recode); and HINOTCOVE (No coverage of any type: Recode).
The basic meaning and universe for this variable are consistent over time. Comparability may, however, be limited by changes in the questions used to gather the information used for back-editing the data, by changes in the back-editing procedures used by the NCHS, and by the 2019 redesign.
The NHIS questionnaire was substantially redesigned in 2019 to introduce a different data collection structure and new content. For more information on changes in terminology, universes, and data collection methods beginning in 2019, please see the user note.
- 1997-2018: All persons.
- 2019-2022: Sample adults age 18+ and sample children age 0-17.