Misclassification of Medicaid Participation by Dual Eligibles: Evidence From the Medicare Current Beneficiary Survey

Previous studies show that survey-based reports of Medicaid participation are measured with error, but no prior study has examined measurement error in an important segment of the Medicaid population-low-income adults enrolled in Medicare. Using the Medicare Current Beneficiary Survey, we examine whether respondent self-reports of Medicaid enrollment match administrative records and present several key findings. First, among low-income Medicare beneficiaries, the false negative rate is 11.5% when the self-report is interpreted as full Medicaid and 3.7% when the self-report is interpreted as full or partial Medicaid. Second, the likelihood of a false negative report is systematically associated with respondent traits. Third, systematic measurement error results in biased coefficient estimates in models of Medicaid participation defined from self-reports, and the bias is more significant when the researcher interprets self-reports as full Medicaid coverage only. Researchers should use caution when interpreting survey reports as pertaining to full Medicaid coverage only.

Automated summary

The study found that there is a measurement error in self-reports of Medicaid participation among low-income Medicare beneficiaries, with a significant false negative rate. Additionally, the likelihood of false negative reports is systematically associated with respondent traits. The researchers also warn about biased coefficient estimates when interpreting survey reports as pertaining to full Medicaid coverage only.