Expansion of government health care programs like Medicaid is sold with the explicit argument that expansion will cover the uninsured. However, expansion may also cause people who are already insured to cancel their insurance or let it lapse so that they can take advantage of a less expensive to them government program. Academic studies of the size of the crowd-out effect arrive at a variety of conclusions ranging from Lo Sasso and Buchmueller’s estimate of a 50 percent crowd-out rate for SCHIP to an 8 percent rate for Dague et al.
Wisconsin runs its own population survey of health coverage. It samples from all Wisconsin households with landline phones (weights adjusted to represent what is known of the cell only population). The response rate is 47 percent, and 2,462 households were interviewed in 2011.
Here are two graphs showing what the survey has found over the last decade. What is most striking is that if the overall rate of coverage has increased, the increase is small. The increase in public coverage of children of about 25 percentage points mirrors a similar loss in private coverage; and the same effect ― but slightly smaller ― is observed in working-age adults.
Whether one likes what has happened to the split between public and private coverage presumably depends upon one’s ideological commitment to government run health care, perspectives on the relative costs of running private or public coverage, perceptions about quality in the two systems, and the equity of various public and private financing mechanisms.