title: What fraction of Medicaid enrollees have private insurance coverage at the time of enrollment? Estimates from administrative data.
abstract: We use administrative data from Wisconsin to determine the fraction of new Medicaid enrollees who have private health insurance at the time of enrollment in the program. Through the linkage of several administrative data sources not previously used for research, we are able to observe coverage status directly for a large fraction of enrollees and indirectly for the remainder. We provide strict bounds for the percentages in each status and find that the percentage of new enrollees with private insurance coverage at the time of enrollment lies between 16 percent and 29 percent, and the percentage that dropped private coverage in favor of public insurance lies between 4 percent and 18 percent. Our point estimates indicate that, among all new enrollees, 21 percent had private health insurance at the time of enrollment and that 10 percent dropped this coverage. Our results show substantially lower rates than previous studies of crowd-out following public health insurance expansions and significant rates of dual coverage, whereby new enrollees into public insurance retain their previously held private insurance coverage.
authors.affiliation: Texas A&M University, College Station, TX USA dague@tamu.edu.
authors.forename: Laura
authors.initials: L
authors.lastname: Dague
authors.affiliation: Georgetown University, Washington, DC, USA National Bureau of Economic Research, Cambridge, MA, USA.
authors.forename: Thomas
authors.initials: T
authors.lastname: DeLeire
authors.affiliation: University of Wisconsin, Madison, WI, USA.
authors.forename: Donna
authors.initials: D
authors.lastname: Friedsam
authors.affiliation: University of Illinois at Chicago, IL, USA.
authors.forename: Lindsey
authors.initials: L
authors.lastname: Leininger
authors.affiliation: Mayo Clinic, Rochester, MN, USA.
authors.forename: Sarah
authors.initials: S
authors.lastname: Meier
authors.affiliation: University of Wisconsin, Madison, WI, USA.
authors.forename: Kristen
authors.initials: K
authors.lastname: Voskuil
mesh_terms: D000368:Aged; D006801:Humans; D019458:Insurance Coverage / Q000706:statistics & numerical data*; D007348:Insurance, Health / Q000706:statistics & numerical data*; D008484:Medicaid / Q000191:economics*; D013221:State Health Plans / Q000706:statistics & numerical data*; D014481:United States; D014922:Wisconsin
keywords: Medicaid; SCHIP; crowd-out