The State Children's Health Insurance Program (SCHIP) was established under the Balanced Budget Act of 1997 and provides federal funds to states to expand health insurance coverage to uninsured low-income children. States use SCHIP money to develop separate child health programs, expand their Medicaid programs, or both. Both Medicaid and CHIP are means-tested government health insurance programs.

As the Field Representative's Manual for 1999 forward notes, the name for the CHIP 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 CHIP program was called the "Healthy Families Program."

The choices included:

• 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 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.

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.

In addition to HICHIPE, IPUMS NHIS contains the following recoded insurance variables: HIHSE (Covered by Indian Health Service: Recode); HIPRIVATEE (Covered by private health insurance: Recode); HIMILITE (Covered by military health insurance: Recode); HIMCAIDE (Covered by Medicaid: 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).