The U.S. Census Bureau's American Community Survey (ACS) undercounted Medicaid beneficiaries by about 7.7% through 2016, according to research published by Health Services Research. The research compared ACS counts to administrative counts in expansion states and non-expansion states before and after 2014. The Census-guided data is used in budgets and to distribute federal financial assistance. The ACS count suggested that Medicaid expansion increased means‐tested coverage in the full population by three percentage points. However, administrative records showed that expansion increased means-tested coverage in the full population by five percentage points. In . . .