Andrew Goodman-Bacon

Department of Economics
Vanderbilt University
2301 Vanderbilt Place
Nashville, TN 37235-1819
Tel: 615/875-8431

E-Mail: EmailAddress: hidden: you can email any NBER-related person as first underscore last at nber dot org
NBER Program Affiliations: DAE , CH , HE
NBER Affiliation: Faculty Research Fellow
Institutional Affiliation: Vanderbilt University

NBER Working Papers and Publications

June 2019Federalizing Benefits: The Introduction of Supplemental Security Income and the Size of the Safety Net
with Lucie Schmidt: w25962
In 1974, Supplemental Security Income (SSI) federalized cash welfare programs for the aged, blind, and disabled, imposing a national minimum benefit. Because of pre-existing variation in generosity, SSI differentially raised payment levels in states below its benefit floor, but had no effect in states that paid above it. We show that SSI increased disability participation in states with the lowest pre-SSI benefits, but shrank non-disability cash transfer programs. For every four new SSI recipients, three came from other welfare programs. Each dollar of per capita SSI income increased total per capita transfer income by just over 50 cents.
September 2018Difference-in-Differences with Variation in Treatment Timing
The canonical difference-in-differences (DD) model contains two time periods, “pre” and “post”, and two groups, “treatment” and “control”. Most DD applications, however, exploit variation across groups of units that receive treatment at different times. This paper derives an expression for this general DD estimator, and shows that it is a weighted average of all possible two-group/two-period DD estimators in the data. This result provides detailed guidance about how to use regression DD in practice. I define the DD estimand and show how it averages treatment effect heterogeneity and that it is biased when effects change over time. I propose a new balance test derived from a unified definition of common trends. I show how to decompose the difference between two specifications, and I apply i...
December 2016The Long-Run Effects of Childhood Insurance Coverage: Medicaid Implementation, Adult Health, and Labor Market Outcomes
This paper exploits the original introduction of Medicaid (1966-1970) and the federal mandate that states cover all cash welfare recipients to estimate the effect of childhood Medicaid eligibility on adult health, labor supply, program participation, and income. Cohorts born closer to Medicaid implementation and in states with higher pre-existing welfare-based eligibility accumulated more Medicaid eligibility in childhood but did not differ on a range of other health, socioeconomic, and policy characteristics. Early childhood Medicaid eligibility reduces mortality and disability and, for whites, increases extensive margin labor supply, and reduces receipt of disability transfer programs and public health insurance up to 50 years later. Total income does not change because earnings replace ...
October 2014The War on Poverty's Experiment in Public Medicine: Community Health Centers and the Mortality of Older Americans
with Martha J. Bailey: w20653
This paper uses the rollout of the first Community Health Centers (CHCs) to study the longer-term health effects of increasing access to primary care. Within ten years, CHCs are associated with a reduction in age-adjusted mortality rates of 2 percent among those 50 and older. The implied 7 to 13 percent decrease in one-year mortality risk among beneficiaries amounts to 20 to 40 percent of the 1966 poor/non-poor mortality gap for this age group. Large effects for those 65 and older suggest that increased access to primary care has longer-term benefits, even for populations with near universal health insurance.

Published: Martha J. Bailey & Andrew Goodman-Bacon, 2015. "The War on Poverty's Experiment in Public Medicine: Community Health Centers and the Mortality of Older Americans," American Economic Review, American Economic Association, vol. 105(3), pages 1067-1104, March. citation courtesy of

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