Why is 5% a big number when we’re looking at catastrophic medical bills, but too small to measure when it comes to diabetes? Because the change in catastrophic medical bills was very large; big enough for the study to pick up.

If it was so irrational for researchers to expect to detect a similar effect on objective measures of physical health, then why did literally 0% of the experts predict that this would be the result of this study? I’m talking about academic luminaries like Jonathan Gruber, in many ways the architect of Obamacare, who was involved in this study and pronounced the results “disappointing”. Not to mention Austin Frakt and Aaron Carroll, the economists who have led the argument that there’s nothing to see here except better financial health. In 2011, Frakt and Carroll were confidently predicting that this study would prove the link between insurance and physical health.

The information that they are now using to declare this study underpowered–the size of the study, and the general incidence of things like hypertension in people between the ages of 18-65–were available back then. Why, then, did they think this study would vindicate their belief in the healing power of health insurance?Because they thought that the improvement in hypertension, cholesterol, and blood sugar control would be bigger. It wasn’t. That is big news.