Another literature review on the relationship between health insurance and mortality and health outcomes has been posted on Ezra Klien’s blog. This one is by Stan Dorn, the author of the Urban Institute study that estimated 18,000 deaths could be blamed on lack of insurance. It is a nice complement to the review provided by Michael McWilliams.
In particular, Dorn goes further than McWilliams in his critique of Richard Kronick’s study upon which McArdle’s conclusions are largely based. This may interest readers of this blog, some of whom have asked for more critique of Kronick.
[T]he main point of Kronick’s study is that some of the earlier research may have overstated the effect of insurance on mortality by omitting important variables. Kronick’s study had its own problems because, as his paper alludes, he was not able to address a critically important methodological issue—namely, that people in poor health are more likely to seek health insurance, which obscures any positive relationship between health insurance and health status. Studies that adjust for this factor have found a statistically and quantitatively significant relationship between lack of insurance and increased mortality risk.
Note what has transpired here. McArdle has characterized Kronick’s study as “what may be the largest and most comprehensive analysis yet done of the effect of insurance on mortality.” That sounds very convincing, as if the Kronick study is the definitive word on this matter. In fact, no single study can be. There is no such thing in social science. Every study, including Kronick’s has some limitations. Even a large and comprehensive analysis can suffer from an important methodological limitation, as Dorn believes Kronick’s does.
Therefore, one needs to base conclusions on a body of work. And as Dorn and McWilliams have both found, among recent studies in this area the evidence is greater than three-to-one in favor of an insurance-health outcome link, including mortality. To reach her conclusions, McArdle ignored the entirety of the research in favor of a small number of studies unrepresentative of the whole.