"Under the assumption of no unmeasured confounders, a large literature exists on methods that can be used to estimating average treatment effects (ATE) from observational data and that spans regression models, propensity score adjustments using stratification, weighting or regression and even...

"This paper investigates the impact of Medicare HMO penetration on the medical care expenditures incurred by Medicare fee-for-service enrollees. We find that increasing penetration leads to reduced health care spending on fee-for-service beneficiaries. In particular, a one percentage point...

"Prices in government and employer-sponsored health insurance markets only partially reflect insurers' expected costs of coverage for different enrollees. This can create inefficient distortions when consumers self-select into plans. We develop a simple model to study this problem and estimate...

"Patient sorting can confound estimates of the returns to physician human capital. This paper compares nearly 30,000 patients who were randomly assigned to clinical teams from one of two academic institutions. One institution is among the top medical schools in the country, while the other...