TightWind is written by Kyle Baxter. Stay Hungry. Stay Foolish.

One interesting side-story to the Oregon Medicaid study story is that the researchers initially published positive results for Medicaid. As a result, looking at how pundits responded to those initial findings and today’s final findings is… interesting. Peter Suderman’s done a good job of it:

Aaron Carroll, an influential health policy blogger at The Incidental Economist, emphasized the rigor of the study. “I’d like to reiterate that this was a randomized controlled trial,” he wrote. “An RCT is pretty much the best way to prove causality, especially if it’s well done.” And because it’s an RCT, he concluded, “we can even start talking causality.” Ezra Klein published a column touting the study with the headline, “Amazing Fact! Science Proves Health Insurance Works.” He explained why the randomized study was so valuable: “The gold standard in research is a study that randomly chooses who gets a new treatment and who doesn’t. That way, you know your results are unaffected by differences in the two populations you are studying.”

Now, well, it’s all a little less clear. “The problem with the Oregon study,” Klein wrote this morning,” …is we don’t really know what we’re learning.” Carroll, who was ready to start talking causality when the first study was published, is now counseling caution. “So chill, people. This is another piece of evidence. It shows that some things improved for people who got Medicaid. For others, changes weren’t statistically significant, which isn’t the same thing as certainty of no effect. For still others, the jury is still out.”

I like Klein and Carroll’s caution today. I just wish they had it when the results were, um, a bit more friendly to their prior beliefs, too.