So many things happened in Massachusetts. Here are just two:
From “The Impact of the Massachusetts Health Care Reform on Health Care Use among Children,” by Sarah Miller:
I find that the Massachusetts reform had a substantial effect on children’s insurance coverage. In particular, the reform reduced enrollment in noncomprehensive public-health programs and increased private insurance coverage. Office visits and checkups increased while emergency room use fell, consistent with the hypothesis that insurance induces substitution away from hospital emergency rooms and toward primary care. After the reform, the fraction of children reported to have forgone medical care because of costs fell to almost zero and reported health quality increased. Overall, these results suggest that the reform improved both the composition of health services used and health outcomes for children.
From “How Did Health Care Reform in Massachusetts Impact Insurance Premiums?” by John A. Graves and Jonathan Gruber:
Premium growth in Massachusetts was by no means an outlier relative to changes observed in other states. For example, the value for Massachusetts [employer-sponsored group] family plans is in the center of the distribution and is only three percentage points below the US average. Similarly, the value for [employer-sponsored group] single plans is 1.8 percentage points above the US average. In each case, the difference is much less than a standard deviation.
By comparison, we find that when we consider growth in nongroup premiums, Massachusetts was a clear outlier relative to the rest of the United States. […] In contrast to ESI premiums , the values for single and family plans in Massachusetts are in the far left tail of the distribution. In other words, relative to other states, nongroup premiums grew at much lower rates in Massachusetts after reform. In fact, the value for single plans in Massachusetts (−40 percent) is 2.2 standard deviations below the US average, and for family plans (−21 percent) it is 1.2 standard deviations below. And unlike the group premium results, the results for nongroup are substantially lower than for other states—no other state had single nongroup premium growth fall by more than in Massachusetts, and only one state (North Carolina) did so for family plans.