Robert Hest
MPP , Senior Research Fellow

p 612-624-5507
e hestx005@umn.edu

Recent Publication Round-Up: The 2021 Medicaid Undercount

Research has consistently shown that surveys that measure health insurance coverage underestimate the number of people enrolled in Medicaid; this is known as the “Medicaid undercount.” SHADAC researchers have long monitored and investigated the magnitude, causes, and effects of the Medicaid undercount across surveys such as the American Community Survey (ACS) and Current Population Survey Annual Social and Economic Supplement (CPS ASEC) and its prevalence across states and populations.

Two recent SHADAC publications investigate the large increase in the size of the undercount in the 2021 ACS, providing new information and guidance for data users:

The first, “Medicaid Undercount Doubles, Likely Tied to Enrollee Misreporting of Coverage,” describes the large increase in the undercount in the ACS, using longitudinal data from the CPS ASEC to analyze the extent to which the increase in the undercount may be tied to an increase in Medicaid enrollees’ misreporting of coverage due to the pandemic-era Medicaid continuous coverage requirement.

The second, “Tracking the Medicaid Undercount in the 2021 ACS Coverage Data,” presents state variation in the 2021 ACS’ undercount, how analytic choices such as health insurance coverage hierarchies and misaligned analytic universes (i.e., all persons vs. noninstitutionalized persons) can affect the apparent size of the undercount, and best practices for using 2021 ACS coverage data in light of the increased undercount.

SHADAC continues to monitor and investigate the Medicaid undercount in surveys of health insurance coverage. The undercount will remain an active area of interest as survey estimates of 2022 health insurance coverage are released later this year and as the “unwinding” of the Medicaid continuous coverage requirement begins this spring.