The number of uninsured Americans is large and growing over time, yet there continues to be debate about exactly how many Americans are uninsured. Researchers use data from several different national surveys to estimate the number of uninsured people in America and discrepancies in their estimates are common.  This brief compares estimates of health insurance coverage from four national health surveys sponsored by the federal government, identifies the differences in their estimates of uninsurance, and identifies  common themes.  Updated September 2013.

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