Key points
- The National Health Interview Survey (NHIS) collects data about health insurance.
- Health insurance is a complex topic, so participants' answers are sometimes inconsistent.
- NHIS uses follow-up questions to capture the most accurate information.
Overview
The National Health Interview Survey (NHIS) collects a wide range of various health information, including information about health insurance coverage. Information about health insurance is collected from one adult and one child (if present) in each household through the adult and child questionnaires. Find more information about the health insurance questions on the NHIS Health Insurance Data page.
Editing health insurance data
Health insurance is a complex topic. Questions related to health insurance can be difficult for NHIS participants to answer accurately. This can lead to answers with conflicting information provided by the same participant. When this happens, NHIS uses follow-up questions to determine which answers are most accurate. If follow-up answers suggest that the original responses were incorrect, NHIS edits those original responses.
The opportunity to clarify and revise responses makes NHIS estimates of health insurance coverage different from other NHIS estimates. For this topic only, some of the data can be reassigned to a different type of coverage or reclassified as "insured" or "uninsured."
Follow-up questions
NHIS collects health insurance plan names, information about people without coverage, and information about coverage from the Health Insurance Marketplace and state-based exchanges. These data can be used with external sources to edit the reported source of coverage.
Participants (respondents) are asked to provide the specific plan name if they report having:
- Private insurance coverage
- Coverage under Medicare Advantage (Part C)
- Coverage under Medicaid, CHIP, or any other state- or government-sponsored plan
Respondents' insurance plan names are manually coded to indicate specific coverage. Plan names may identify coverage as something different than what was reported by respondents. For example, a respondent stated they have a private comprehensive plan but provided the name as "Medicaid." That person would be coded as having Medicaid coverage rather than private coverage.
Respondents who report no coverage for themselves or the sample child are then asked:
- How long each family member has the child been without coverage?
- Reasons why the child stopped being covered (for those uninsured for less than 3 years)?
- Reasons the child still does not have health insurance?
Sometimes the responses to these questions indicate that a person actually might have coverage. This results in a small fraction of those who were originally classified as uninsured being assigned a type of coverage.
To learn about how NHIS collects exchange-based coverage information, read the rules for evaluating and assigning exchange-based coverage.
Health insurance coding manual
NHIS uses a coding manual to assign specific codes to different health insurance plan types. The manual lists names of private health insurance plans and public programs and plans. The manual includes information from many commercial and government sources. NHIS updates it annually.
NHIS has developed coding manuals for more than 50 years. Since 1962, NHIS has maintained a list of all "Blue" plans (Blue Cross and Blue Shield) for editing NHIS data. NHIS revised the list in 1963 because of mergers, separations, and name changes.
The current manual contains between 4,000 and 5,000 plan names. Plan names are organized by state. The coding manual identifies each plan by its registered name and includes a code to identify features of the plan.
The current sources of information for health insurance plan coding include resources provided by other agencies and groups. Sources also include publicly available information that the National Center for Health Statistics (NCHS) has collected in internal resources.
Information from external sources
- HMO/PPO Directory (Grey House Publishing)
- Centers for Medicaid and Medicare Services
- AIS Directory of Health Plans (MMIT Network)
- Listing of Medigap Plans from CSG Actuarial
- National Association of Insurance Commissioners
- Medicare Advantage Plans (Robert Wood Johnson Foundation and Centers for Medicare and Medicaid Services)
- Guide to Federal Benefits
- Exchange Issuer and Exchange Plan name list (Robert Wood Johnson Foundation)
Information compiled by NCHS
- Medicaid Managed Care Plan list (compiled by NCHS from internet searches)
- Names of other public programs (compiled from internet searches)
Recoding
The editing process generates a series of new variables including:
- Indicators of coverage type
- For private plans, a code describing the coverage provided by up to two private plans reported for each sample adult and sample child respondent.
- MEDICARE_A
- MEDICAID_A[C]
- PRIVATE_A[C]
- CHIP_A[C]
- IHS_A[C]
- MILCARE_A[C]
- OTHPUB_A[C]
- OTHGOV_A[C]
- NOTCOV_A[C]
NOTCOV_A and NOTCOV_C reflect the definition of noncoverage as used in Health, United States. That definition considers people who have only Indian Health Service coverage to be uninsured.
Analysts are strongly advised to use the above recodes for estimates of types of health care coverage and NOTCOV_A and NOTCOV_C to derive estimates of uninsurance.
If users want to count IHS as coverage or create any other definition of uninsurance, they may also use the health insurance codes above.
For those users who wish to review the originally reported health insurance coverage types prior to editing and back-coding, they are available in the HIKIND01_A through HIKIND10_A, MCAREPRB_A and MCAIDPRB_A for adults, and HIKIND01R_C, HIKIND04_C through HIKIND08_C, HIKIND09R, MCAIDPRB_C variables for children.
Early Release insurance data
The NHIS Early Release Program provides quarterly tables, biannual reports, and preliminary microdata files ahead of the full release of survey data. Users can access health insurance coverage data in advance of the annual release of NHIS data.
NCHS developed a streamlined version of the usual final editing process to produce the NHIS Early Release reports. This alternative method still attempts to determine accurate coverage sources but does not assign detailed codes to individual health plans. The streamlined editing uses both automated and partially automated procedures with limited, targeted manual review.
Learn more about the NHIS Early Release Program.