Whether you like or dislike the Affordable Care Act, it helps to understand the distinction between statistical significance and practical importance.
Taxpayers want to know whether the government programs they pay for actually make a difference, so measurement is a critical part of policy evaluation. That’s where econometric and statistical analysis comes in: gather data under various policy implementations and try to measure the differences.
Take the act’s major expansion of Medicaid benefits, going to able-bodied adults living at or below 133 percent of the poverty line (without regard to asset ownership), which will occur in most states at the beginning of next year. Will the expansion make adults healthier?
An important study, published in The New England Journal of Medicine in May, set out to help answer the question by examining an Oregon-specific Medicaid expansion in 2008. In their short summary of conclusions, the authors wrote, “Medicaid coverage generated no significant improvements in measured health outcomes.” Opponents of the Medicaid expansion quote that sentence, telling us that we might not want to expand a health program that doesn’t actually make people healthier. Proponents of the expansion acknowledge the conclusion, too, and try to help readers find encouraging results elsewhere in the study.