Via Megan, here is an excellent discussion of the study, here is one excerpt:
In summary, based on statistically insignificant effects of coverage from the Oregon Experiment: (1) The effects that are closest to statistical significance are that coverage would increase the rate of smoking and damage the cardiovascular prognosis of sick people; (2) the best estimated net effect on total population cardiovascular health is extraordinarily tiny; (3) this effect would be achieved by making the sick sicker, while very slightly improving the health of already healthy people ; and (4) this effect is almost certainly unattractive on a risk-adjusted basis. This is not a series of effects that makes a very attractive argument for an increase in health from the experiment.
…When interpreting the physical health results of the Oregon Experiment, we either apply a cut-off of 95% significance to identify those effects which will treat as relevant for decision-making, or we do not. If we do apply this cut-off (as the authors did; as is consistent with accepted practice for medical RCTs; and as is what I believe to be a good way to make decisions based on experiments), then we should agree with the authors’ conclusion that the experiment “showed that Medicaid coverage generated no significant improvements in measured physical health outcomes in the first 2 years.” If, on the other hand, we wish to consider non-statistically-significant effects, then we ought to conclude that the net effects were unattractive, mostly because coverage induced smoking, which more than offset the risk-adjusted physical health benefits provided by the incremental utilization of health services.
Do read the whole thing, there are many more points of interest. For instance “Almost half the people offered free health insurance coverage didn’t bother to send back the application to get it.”