For example, the Center for Medicare and Medicaid (CMS) published a listing of insurance plans contracting with Medicaid in each state in a 2009 report entitled, "2009 National Summary of State Medicaid Managed Care Programs." Users may want to review other documents from the CMS for further information on such payment arrangements.

Persons with three or more plans have a "yes" response in HIPRIVGT2 (available for 2004 forward). Analysis by IHIS staff indicates that a very small number of persons (less than 0.2 percent of the total number of individuals with private health insurance per year for 2004 to 2009) had three or more private insurance plans.

For 1997 to 1999, only people with an affirmative answer to this initial question have responses to follow-up questions about their kind of health insurance and the details of coverage; for 1997 to 1999, those who did not say "yes" 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").

For 1997 forward, the NHIS Field Representative Manuals defined private health insurance to be any type of health insurance, including Health Maintenance Organizations (HMOs), other than the public programs of Medicare, Medicaid, Military health care/VA, CHAMPUS/TRICARE/CHAMP-VA, Indian Health Service, state-sponsored health plans, and health insurance from other government programs (including CHIP, the Children's Health Insurance Plan, for 1999 forward).

For 2001 forward, the Manuals indicated that insurance coverage through COBRA (the Consolidated Omnibus Budget Reconciliation Act of 1985) or by
TCC (Temporary Continuation of Coverage) should be classified as private health insurance (obtained through an employer or workplace).

For 1997 forward, the definition of private insurance remained largely the same, and consistently excluded single service plans. Over a longer time span, the definition and data collection process for private insurance changed greatly (as is documented in the User Notes on "Changes in the Definition of Private Insurance" and "Changes in the Data Collection Process").

The categories of self or family (living in the household), employer or union, someone outside the household, Medicare, and Medicaid were available for all years. For 1999 forward, respondents could report payment by the Children's Health Insurance Program. From 1998 forward, the category "state or local government or community program" was used in place of the 1997 category of "government program."