We implement an empirical test for selection into health insurance using changes in coverage induced by the introduction of mandated health insurance in Massachusetts. Our test examines changes in the cost of the newly insured relative to those who were insured prior to the reform. We find that...

In April 2006, the state of Massachusetts passed legislation aimed at achieving near universal health insurance coverage. A key provision of this legislation, and of the national legislation passed in March 2010, is an individual mandate to obtain health insurance. Although previous researchers...

Prior studies suggest that, with elastically supplied inputs, free entry may lead to an inefficiently high number of firms in equilibrium. Under input scarcity, however, the welfare loss from free entry is reduced. Further, free entry may increase use of high-quality inputs, as oligopolistic...

Market provision of impure public goods such as insurance retirement savings and education is common and growing as policy makers seek to offer more choice and gain efficiencies. This approach induces an important trade-off between improved surplus from matching individuals to products and...

Group testing increases efficiency by pooling patient specimens and clearing the entire group with one negative test. Optimal grouping strategy is well studied in one-off testing scenarios with reasonably well-known prevalence rates and no correlations in risk. We discuss how the strategy...

COVID-19 has created a dual set of stresses on health care systems worldwide: a rise in expensive intensive care services and a dramatic decline in elective services. The U.S. government has responded with both grant and loan programs to help health care providers weather the storm. But the...

In numerous high stakes markets skilled experts play a key role in facilitating consumer choice of complex products. New artificial intelligence (AI) technologies are increasingly being used to augment expert decisions. We study the role of technology and expertise in the market for health...

An event study generates only a lower bound on the full effect of an event unless researchers know the probability that investors assigned to the event before it occurred. We develop two model-free methods for recovering the market's priced-in probability of events. These methods require running...

We study the welfare effects of offering choice over financial coverage levels--"vertical choice''--in regulated health insurance markets. Though the efficient level of coverage, which trades off the value of risk protection and the social cost from moral hazard, likely varies across consumers,...

The regulated insurance exchanges set up in the Affordable Care Act (ACA) were designed to deliver affordable, efficient health coverage through private insurers. It is crucial to study the complex industrial organization (IO) of these exchanges in order to assess their impacts to date, during...