FIGURE B.2 Probability of being uninsured for population under age 65, by state, 2001.

SOURCE: Fronstin, 2002, estimates based on March 2001 Current Population Survey.

each of which gives a different picture of uninsurance: persons who report being uninsured at the time of the survey, or a point estimate (average 15 percent uninsured rate for persons under age 65, or about 4.5 million people); persons reporting uninsured status at any time in the previous 12 months (average 21 percent uninsured rate, 6.2 million people); and persons uninsured for the entire 12 months preceding the survey interview (12 percent, or 3.6 million people) (Brown et al., 2002). Many more people experience being uninsured for relatively short times than are captured in the point estimates made on the basis of data from the Census Bureau’s annual CPS (IOM, 2001a; Short, 2001). The median duration of an uninsured spell is between five and six months (Bennefield, 1998). Both the length and the frequency of uninsured periods vary with the source of coverage and among different populations. For example, persons covered under individual policies are more likely to experience an uninsured period compared to persons with employment-based coverage, and persons experiencing long periods of uninsurance are more likely to be lower income (earning less than 200 percent of the federal poverty level [FPL]) (IOM, 2001a).

Estimates of uninsured rates are available for regions or counties within most states. These estimates have been developed using a few different approaches. This