The Measurement of Medicaid Coverage in the SIPP

This article studies the accuracy of reported Medicaid coverage in the Survey of Income and Program Participation (SIPP) using administrative records from the State of California. Overall, we estimate that the SIPP underestimates Medicaid coverage in the California population by about 10%. The probability of correctly reporting coverage for those actually covered by Medicaid is around 85%, and is even higher for low-income children. The probability that people who are not covered by Medicaid incorrectly report that they are covered is about 1.3% for the population as a whole, but is higher (up to 7%) for low-income children.