A groundbreaking study by some of the nation's top health economists "gives the clearest answer yet to a key question" that, surprisingly, we don't have much good data on, says Anna Wilde Mathews in The Wall Street Journal: "How are people affected by gaining health insurance?" Due to budget constraints, Oregon held a lottery in 2008 for 10,000 slots in its Medicaid program, creating a randomly selected pool of newly insured low-income residents, and a control group to compare them against — the "gold standard "of scientific research. And it turns out that the Medicaid recipients were not only happier, but healthier, too. The issue is particularly relevant because, under President Obama's Affordable Care Act (ACA), a huge influx of Medicaid participants and other newly insured citizens will enter the U.S. health care system in 2014. Does this Oregon study prove that health insurance make you healthier?

Not surprisingly, yes: The study found that people with Medicaid aren't just better off than people without insurance, they're "a lot better off," says Jonathan Cohn at The New Republic. They go to the doctor more often, report feeling much healthier and happier than the control group, and are financially better off. Much of this should be "a no-brainer," but it wasn't to the "cadre of conservative writers" who have been arguing that Medicaid and President Obama's health care reforms are useless.
"Attention conservatives: Yes, Medicaid works"

The study doesn't prove much, actually: "ObamaCare" supporters want this paper to justify their leap-of-faith expansion of Medicaid, but it "does not provide the vindication they seek," says Michael F. Cannon at National Review. The study doesn't meet their burden of proof that Medicaid not only improves health, but also does so "at a lower cost to taxpayers than alternative policies," like lowering taxes. Also, much of the purported gains among these Medicaid recipients appear to be psychological.
"Oregon's verdict on Medicaid"

The research is persuasive, but not perfect: "There are limits to what you can extrapolate from one, single-year study of 10,000 Medicaid recipients in Oregon," says Ray Fisman at Slate. Still, this represents "the best evidence we've got" on how insurance affects mental and physical health, and the initial verdict is that the impact "is enormous, and delivered at relatively low cost." The shocking increase in happiness alone makes "Medicaid ridiculously good value for money."
"Does health coverage make people healthier?"