Matthew Yglesias twitters "Do rightwingers really believe that US health insurance has no mortality-curbing impact?" Austin Frakt suggests that I am somehow in the grip of this ridiculous belief, and goes onto say that the state of knowledge is beyond the point where we need to understand the size of the effect.
I question the description of myself and Tyler Cowen as "rightwingers"--conservatives hate a good third of my positions at least.
But to answer the question anyway, I thought I'd made it clear, but apparently not: I think it is possible that the lack of insurance has no effect on aggregate mortality statistics. I do not think that this is likely, but I think it's possible. What I think is likely is that the effect is not that large, because if it were large, it would be very surprising to see so little effect on the mortality of an elderly population with a high mortality rate, or to have a study that samples 600,000 people and finds no effect.
Mostly what I think is that the statistics are really, really flawed. Not because the authors are bad social scientists, but because this stuff is so hard to tease out. Natural experiments are rare, and data sets often hard to come by.
This is about how I feel about the minimum wage. My intuition is that demand curves slope downward, so if you raise the price of labor, employers are likely to consume less of it. But if you can get a study like Card and Krueger, than the effect simply can't be that large--at least, within the range that the US usually plays with the minimum wage. I don't think it's particularly good public policy, because too much of it goes to middle class teenagers and the like, and even small disemployment effects are dangerous for vulnerable populations. But I don't think it's super-terrible public policy either.
I'm much more convinced by the benefits of health insurance for certain subpopulations, particularly people with diseases we're very good at treating. HIV seems to pretty convincingly respond to offering public treatment--which also has a pretty compelling public health rationale. (I don't want to hear anything about spears mounted on steering wheels, thank you very much). Medicaid expansions provide some pretty good natural experiments, IMHO, indicating that you can improve infant mortality. Poor people with hypertension get better blood pressure control pretty consistently.
But this doesn't imply a large effect in the macro data if we extended health coverage, precisely because not that many people under the age of 65 die of things we can treat. That whole age group is only about a quarter of deaths, and some of them are from things like metastatic cancer or auto deaths, in which more health care coverage can at best eke out moderate further improvements. (That may not be true in the future. It is now, sadly.)
Obviously, this matters. If 45,000 people die a year, this makes a more urgent case for overlooking the drawbacks of single payer than if 1,000 people die a year--there are probably more cost-effective ways to control those deaths.
But that is far from the whole calculation. The mortality question is really important, but it doesn't touch non-mortality outcomes, which are even harder to measure comprehensively. It doesn't touch on the financial questions raised by medical bankruptcies--I think they're overstated by the Himmelstein/Woolhandler crowd, but that doesn't mean I think they don't exist. It doesn't address the social justice questions. It just says, this is probably not the best grounds upon which to make the case for national health care, because we don't have a good handle on the number.
What it might do is point us towards the shape of expansions. To the extent that the data make a strong case, it might point to more modest interventions: prenatal and infant care. Tuberculosis and HIV. Certain kinds of chronic conditions (hypertension is really relatively cheap to treat, and very important, although as with diabetes compliance is apparently a giant problem even when there aren't cost barriers). I'd probably support most of these.
But the core question for me is not whether there's any effect--I'm willing to consider the possibility there isn't, but I tend to assume there is. The question is, how big? Because if it exists, but it's too small to measure, it might not be the issue our government should be most focused on. Particularly when you consider that there are costs, as well as benefits, to a national health care system.