Medicaid demonstrations aren't properly evaluated. Randomized trials could fix that

Section 1115 waivers in the Medicaid program are meant to be experiments for states to test coverage approaches that don't meet federal requirements. However, most of those evaluations fall far short, lacking the rigorous study design needed to properly evaluate them, according to a new commentary in the New England Journal of Medicine. The evaluations usually use before-and-after comparisons and difference-in-difference analyses, both of which contain numerous methodological limitations. Moreover, the Government Accountability Office has found these evaluations often contain small sample sizes and no comparison groups. They also fail to test certain hypotheses and report all outcomes.