• Medicaid undercount;
  • validation study;
  • survey and administrative data;
  • uninsurance;
  • health insurance coverage


To synthesize evidence on the accuracy of Medicaid reporting across state and federal surveys.

Data Sources

All available validation studies.

Study Design

Compare results from existing research to understand variation in reporting across surveys.

Data Collection Methods

Synthesize all available studies validating survey reports of Medicaid coverage.

Principal Findings

Across all surveys, reporting some type of insurance coverage is better than reporting Medicaid specifically. Therefore, estimates of uninsurance are less biased than estimates of specific sources of coverage. The CPS stands out as being particularly inaccurate.


Measuring health insurance coverage is prone to some level of error, yet survey overstatements of uninsurance are modest in most surveys. Accounting for all forms of bias is complex. Researchers should consider adjusting estimates of Medicaid and uninsurance in surveys prone to high levels of misreporting.