I develop a model of a randomized experiment with a binary intervention and a binary outcome. Potential outcomes in the intervention and control groups give rise to four types of participants. Fixing ideas such that the outcome is mortality, some participants would live regardless, others would...

The LATE monotonicity assumption of Imbens and Angrist (1994) precludes "defiers," individuals whose treatment always runs counter to the instrument, in the terminology of Balke and Pearl (1993) and Angrist et al. (1996). I allow for defiers in a model with a binary instrument and a binary...

Current mammography guidelines reflect evidence that mammography could be harmful on average through the overdiagnosis of breast cancers that would not eventually cause symptoms in the long term. To inform targeting within these guidelines, I investigate whether some women are more likely to...

The extent to which consumers respond to marginal prices for medical care is important for policy. Using recent data and a new censored quantile instrumental variable (CQIV) estimator, I estimate the price elasticity of expenditure on medical care. The CQIV estimator allows the estimates to vary...

A fundamental concern for researchers who analyze and design experiments is that the experimental result might not be externally valid for all policies. Researchers often attempt to assess external validity by comparing data from an experiment to external data. In this essay, I discuss...

I aim to shed light on why emergency room (ER) utilization increased following the Oregon Health Insurance Experiment but decreased following a Massachusetts policy. To do so, I unite the literatures on insurance and treatment effects. Under an MTE model that assumes no more than the LATE...

I examine treatment effect heterogeneity within an experiment to inform external validity. The local average treatment effect (LATE) gives an average treatment effect for compliers. I bound and estimate average treatment effects for always takers and never takers by extending marginal treatment...

Young people with private health insurance sometimes transition to the public health insurance safety net after they get sick, but popular sources of cross-sectional data obscure how frequently these transitions occur. We use longitudinal data on almost all hospital visits in New York from 1995...

I examine the impact of state policy decisions on the early impact of the ACA using data through the first half of 2014. I focus on the individual health insurance market, which includes plans purchased through exchanges as well as plans purchased directly from insurers. In this market, at least...

Insurance induces a well-known tradeoff between the welfare gains from risk protection and the welfare losses from moral hazard. Empirical work traditionally estimates each side of the tradeoff separately, potentially yielding mutually inconsistent results. I develop a nonlinear budget set model...