The goal of the Affordable Care Act (ACA) was to achieve nearly universal health insurance coverage in the United States through a combination of insurance market reforms, mandates, subsidies, health insurance exchanges, and Medicaid expansions, most of which took effect in 2014. Daniel Zapata co-authored a research paper using data from the American Community Survey to estimate the causal effects of the ACA on health insurance coverage.
Data for this study came from the American Community Survey (ACS), administered by the Census Bureau, that samples around 1% of the US population. Researchers used a difference-in-difference-in-differences model, in which the differences came from time, state Medicaid expansion status, and local area pre-intervention uninsured rate.
Results indicated that implementing the full ACA provisions increased the number of residents with insurance by 5.9 percentage points, while states that did not expand Medicaid only saw an increase of 3.0 percentage points. Private insurance expansions from the ACA were due to increases in both employer-provided and non-group coverage. The coverage gains from the full ACA were largest for people living below the Medicaid eligibility threshold, non-whites, young adults, and unmarried individuals. Researchers found some evidence that the Medicaid expansion partially crowded out private coverage among low-income individuals. This study provides evidence about the ACA's early effects, which policymakers could use to guide future healthcare decisions.