• Oregon and Medicaid – how the debate has changed

    I’ve spoken to a number of people in the media today about the Oregon Medicaid study. On the whole, they asked excellent questions, and made me think about my own interpretation of the results. They also forced me to think about how I would be speaking about the study if the results had been amazing. Would I still “quibble” about power?

    Here’s the thing. If they had shows statistically significant improvements in health outcomes, I’d be impressed. If they had shown statistically significant harms, I’d be concerned. Non-significance doesn’t tell us that much, especially if the study is underpowered.

    But am I being fair? Consistent? Some have accused me of changing course. So I looked back at what I’d written previously, when I said “we could even start talking causality”. Here’s what I said:

    But I’d like to reiterate that this was a randomized controlled trial. An RCT is pretty much the best way to prove causality, especially if it’s well done. So if you wanted to prove that Medicaid causes bad outcomes (as many do), this would be the way to prove it.

    Not too long ago, ACA opponents were claiming that Medicaid was bad for health. Some even claimed it killed people. So I was eager to see if an RCT would find that. The initial results were positive and statistically significant. So I concluded:

    Randomized controlled trials on this scale happen rarely. We’re still talking about the RAND health insurance experiment, which occurred decades ago. Here’s one that shows that Medicaid is both good for health and provides a significant financial benefit for it’s recipients. Since it’s an RCT, we can even start talking causality.

    There’s no such studies or evidence showing the opposite, that Medicaid is bad for health. We’ll see if that talking point goes away.

    There is still no evidence that Medicaid is bad for health. But if anyone has moved the goalposts, it’s the people claiming that now Medicaid must prove it improves health, instead of just not harming people. I stand by everything I said before. I think I’ve been pretty consistent.


    • The Oregon Experiment does not show Medicaid is bad for health. I doubt that that Medicaid is such a horrific program that it is bad for patients’ health.

      But today my Congressman, a medical doctor, cited a different study in an email in order to suggest that Medicaid is bad for health. He tells his constituents that this study shows “those on Medicaid were 13% more likely to die than those with no insurance at all.”

      Let me avoid mentioning the name of this Congressman, who happens to be a medical doctor.

      • There are so many of these studies. They are not showing causation. That requires a more more careful research design.

      • I’ll out him. We’re talking about William Cassidy (R-LA). But more to the point, it would be surprising if people on Medicaid weren’t more likely to die than those not. After all, Medicaid is restricted to groups that tend to be at greater risk (the poor, young and on their own, etc.). As Austin notes, showing causation requires careful study design.

      • I would argue that the risk of death for Medicaid patients is probably the same as the risk of death for everyone else: 100%.

    • You wouldn’t need to “quibble” about power if there were statistically significant results because power would be irrelevant at that point! I know you know this, but I hope you explained it to these people.

    • It’s the intersection of hard science and social science that is the controversy here. Social science might explain why people see a doctor, or eat too many hamburgers and french fries, but only the hard science can explain why people are sick, or get better, worse, or die. An economist might explain why people save, or work, don’t work, or save, but she isn’t going to make conclusions about the connection between these human behaviors and the health of the subjects studied. Moreover, the potential for mischief at the intersection of social science and hard science is great, because conclusions reached have much greater credibility – we expect differing conclusions from different social scientists but only one conclusion from hard scientists. With social science, we will never reach finality because human behavior is determined by so many variables. With hard science, we expect to reach finality because the laws of nature are inviolate (even if so complex that it’s impossible to really know them all). This isn’t a criticism of social science or collaboration between social scientists and hard scientists, but a reminder that the two view the world differently and the results of their collaboration can be useful but limited.

    • It is still too early. It is evidence but very little evidence never the less it is in keeping with the findings of Robin Hanson.