For those who think all decisions should be made the way a business would make them, R.O.I. is as American as apple pie – elemental, sweet and satisfying. In this mode of deliberation, projected – or better yet proven – Return On Investment separates the “go” projects from the “no-go” ones. The higher the R.O.I. the better, and the more certain we can be about it, the more prudent the investment is considered

Harvard researchers painstakingly examined data and published in the New England Journal of Medicine the conclusion that expanding Medicaid decreased rates of delayed care (a proxy for cost savings), increased rates of self-reported “excellent” or “very good” health status, and flat-out saved lives (known in research-speak as “a significant reduction in adjusted all-cause mortality”). The data came from expansions in Arizona, Maine and New York and the results in those states were meticulously compared and contrasted with non-expansion results in Pennsylvania, Nevada, New Mexico and New Hampshire.

This is compelling evidence, work that corroborates the Oregon experience. No study is perfect – there is always the issue of correlation vs. causation that cannot be ignored in population studies – but the methods, the credentials and the conclusions have earned the respect of health economists and more conservative-leaning organizations, as reported in the New York Times and other outlets.

In the pantheon of valued R.O.I.’s, “deaths prevented” would have to be pretty high on the list. On the scale of proven vs. projected, state-specific data compared to similar states and corroborated by contrasting states seems to stand up to scrutiny.

If R.O.I is your apple pie, then Medicaid expansion is your horse in Arizona’s upcoming budget race.