Medicaid undercount and bias to estimates of uninsurance: new estimates and existing evidence.
OBJECTIVE
To examine whether known Medicaid enrollees misreport their health insurance coverage in surveys and the extent to which misreports of lack of coverage bias estimates of uninsurance.


METHODS
Primary survey data from the Medicaid Undercount Experiment.


METHODS
Analyze new data from surveys of Medicaid enrollees in California, Florida, and Pennsylvania and summarize existing research examining bias in coverage estimates due to misreports among Medicaid enrollees.


METHODS
Subjects were randomly drawn from Medicaid administrative records and were surveyed by telephone.


CONCLUSIONS
Cumulative evidence shows that a small percentage of Medicaid enrollees mistakenly report being uninsured, resulting in modest upward bias in estimates of uninsurance. A somewhat larger percentage of enrollees report having some other type of coverage than no coverage, biasing Medicaid enrollment estimates downward but not biasing estimates of uninsurance significantly upward. Implications for policy makers' confidence in survey estimates of coverage are discussed.
School of Public Health, University of Minnesota, 2221 University Avenue SE #345, Minneapolis, MN 55414, USA.
Kathleen Thiede
KT
Call
Gestur
G
Davidson
Michael
M
Davern
Rebecca
R
Nyman
D000293:Adolescent; D000328:Adult; D015982:Bias; D003625:Data Collection; D006801:Humans; D007348:Insurance, Health / Q000706:statistics & numerical data*; D008484:Medicaid; D017057:Medically Uninsured / Q000706:statistics & numerical data*; D008875:Middle Aged; D014481:United States