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National Information Center on Health Services Research and Health Care Technology (NICHSR)

Estimating the Uninsured Population
The number of people who do not have health insurance is an important indicator of access to the health care system. There are several measures that can be used. [For more detailed information see the Census Bureau’s website discussion of sources of this data.]

Selecting which measures to use can have an effect on the actual number cited, but more importantly, different estimates provide more or less detail about the kinds of people who lack health insurance.

The definition of “coverage” also differs. For example, should the number lacking health insurance include anyone who did not have health coverage during a calendar year as uninsured or should it be limited to those who lacked health insurance during the entire year?

  • The Census Bureau conducts an annual survey [the March supplement to the Current Population Survey] that asks people if they have health insurance coverage. It also collects similar information in a related survey [The Survey of Income and Program Participation.]
  • The Census Bureau has also created an experimental method to model the distribution of the uninsured. This procedure attempts to estimate the number of people in each state and county who lack health insurance.
  • This information is also collected on surveys conducted by the National Center for Health Statistics.
  • CDC’s Behavioral Risk Factor Surveillance System also collects this data on surveys conducted by state governments.
  • The Agency for Healthcare quality and research also collects detailed information about health insurance and its use.