Under-Reporting of Medi-Cal and Welfare in the March Current Population Survey: An Analysis of Matched Survey-Administrative Data

Jacob A. Klerman, RAND
Jeanne Ringel, RAND

The March Current Population Survey (CPS) is a standard data set for the analysis of issues related to welfare program participation, Medicaid participation, and health insurance coverage. Unfortunately, CPS estimates of the number of program participants are well below administrative data totals and there is some evidence that the difference is growing. To improve understanding of these issues, with the cooperation of the Census Bureau and the State of California, we matched administrative data from California's Medicaid system (Medi-Cal, including cash assistance) to March CPS data for 1990-2000, by Social Security Number (SSN). For those individuals who provided an SSN, we consider the congruence of the survey data and the administrative data, and in particular how reporting error varies across sub-groups and through time. Finally, we consider the implications of the matched analysis for other analyses using the CPS.