Some thoughts about the Oregon Health Study - which is being dissed by MR here and here.
First off the comparison of this study to Reinhart and Rogoff is way off base. Reinhart and Rogoff were recalcitrant in sharing their data. Had they been more forthcoming in the first place it is possible that someone would have pointed out the Excel error much earlier. Instead they left all the researchers puzzled over their attempts to replicate their findings. This is NOTHING like Reinhart Rogoff.
What if they had found positive effects? Then I think the debate would have shifted to size effects and whether the results were meaningful in any sense. The critics are leaping to the "no result" finding as a way to justify their opposition. They would probably have leaped to a positive result by pointing out the lack of meaningful results regardless.
RCTs are pretty useless in this debate. Think of their outcomes - blood pressure, hypertension and cholesterol levels. How can having insurance by itself promote better outcomes? To actually change these outcomes, insurance holders have to actually change their behavior. There is a lot of behavioral economics evidence out there to argue against anyone actually doing anything about this regardless of health insurance status.
This is an example of RCTs taking away the analysts' ability to think straight. Retrospection would have predicted the null effect. The low income population makes them even more constrained in their ability to affect lifestyle changes that would positively affected the outcome measures. I have some doubt as to whether even a high income population would have been able to affect the lifestyle changes necessary to have a detectable effect.
This is an example of RCT measuring the wrong outcome. We only measure what we can see or even worse - what is easiest to measure. By some kind of fluke these are the outcomes that are hardest to change. I have to change my diet, my exercise regimen, my sleep habits, and so forth. If this is hard for a middle class person how much harder would it be for a low income group?
Effects of the recession on health? Is it possible that the stress of the recession and the job market is driving the results in both treatment and control?
This randomized study should have been titled something like "How much do people take their doctors' advice in changing their lifestyles? An analysis of low income population using Medicaid lotteries" or something similar. Would the findings have made any headlines then?
Alternatively, if the study participants were given medications to treat their hypertension, cholesterol, etc. then the study would have been about the efficacy of drugs on the low income population. Or perhaps prescription drug compliance among the low income population.
The comeback "You still buy health insurance don't you?" is a reasonable response contrary to what Tyler Cowen thinks. And this returns to the possibility that the benefits of ACA and expansion of Medicaid was oversold. Why do we buy health insurance - surely not to become healthier. We buy insurance to preserve the status quo, i.e. I don't want my health to get worse and if it gets worse then at least I can do something about it. I have health insurance and I can go to the doctor. And when we think about health we generally don't think in terms of cholesterol or blood pressure. We think of actual illnesses, pain, discomfort, etc. and again evidence from behavioral economics may be useful here.
What is going here I think is that possibly and perhaps in fact, very likely that supporters of ACA felt they had to justify the expansion of Medicaid by some evidence based reason and like their opponents who will grab at anything they can to fight against it they fell onto the belief that health insurance improves overall health - not specific illnesses, but overall health because it was easier to measure in an RCT.
Instead of making arguments for ACA on grounds of equity and perhaps even a right to adequate care and a right not to impose the costs of emergency room visits on others, etc. they have backed themselves into a corner with this null finding.