The CPS estimates are based on ERIU tabulations of data collected by the U.S. Census Bureau in the Current Population Survey (CPS) Annual Social and Economic Supplement, conducted in March of 2002. CPS estimates of the uninsured are intended to represent persons who are uninsured throughout calendar year 2001. A person is considered insured if they were covered at any time during that calendar year; individuals insured for only one month are counted as insured. CPS estimates of the uninsured should be interpreted with caution. Respondents are asked to report on a time period that begins roughly 15 months prior to the time of the interview. Some respondents are likely to have trouble remembering back this far, while others may be confused by the time frame and respond instead about current coverage status. Studies that have examined and compared CPS estimates with data from other surveys suggest that CPS estimates of the uninsured are much closer to "point in time" than true full-year estimates.
The SIPP estimates are ERIU tabulations of data collected by the U.S. Census Bureau in the Survey of Income and Program Participation (SIPP) 2001 panel, which began in January 2001. The SIPP interviews respondents every four months over a period of roughly 4 years. The 2001 tabulations are based on responses to the first three interviews (waves) of the 2001 panel, covering a 12-month period that corresponds with calendar year 2001 for one of the four rotation groups. Respondents report whether they were covered by specific sources of public or private health insurance (Medicare, Medicaid, SCHIP, other public, employment-based private, other private health insurance). Respondents are considered uninsured if they respond "no" to all of the coverage options; they are not asked directly if they are uninsured. Respondents are considered uninsured if they respond "no" to all of the coverage options; they are not asked directly if they are uninsured. The "point in time" estimate reflects health insurance status in the 12th survey month. The "all year uninsured" estimate includes those without health insurance for all 12 months. The "ever uninsured" includes those reporting no health insurance for at least one month and for as many as 12 months.
discussion of issues related
to counting the uninsured
and Characterizing the Uninsured," (Adobe
PDF) by Pamela Farley Short,
and ERIU Research
Highlight 1: A Revolving
Door: How Individuals Move
In and Out of Health Insurance
Coverage (Adobe PDF)
Notes on CPS Data Source and Variables (PDF)
Notes on SIPP Data Source and Variables (PDF)