A positive correlation between insurance coverage and ex post risk can be an indicator for private information in insurance markets. However, this test fails if agents have heterogeneous risk attitudes. We propose a new test that conditions on unobserved types of individuals who differ in their...

We present a graphical framework for analyzing both theoretical and empirical work on selection in insurance markets. We begin by using this framework to review the "textbook" adverse selection environment and its implications for insurance allocation, social welfare, and public policy. We then...

I use the Medicare Part D prescription drug insurance market to examine the dynamics of firm interaction with consumers on an insurance exchange. Enrollment data show that consumers face switching frictions leading to inertia in plan choice, and a regression discontinuity design indicates...

The Affordable Care Act (ACA) will dramatically alter health insurance markets and the sources through which individuals obtain coverage. As the ACA is implemented, it is essential to monitor the intended and the unintended consequences of these regulations. To evaluate the changes in health...

Standardization of complex products is touted as improving consumer decisions and intensifying price competition, but evidence on standardization is limited. We examine a natural experiment: the standardization of health insurance plans on the Massachusetts Health Insurance Exchange....

We examine whether and to what extent consolidation in the U.S. health insurance industry is leading to higher employer-sponsored insurance premiums. We make use of a proprietary, panel dataset of employer-sponsored healthplans enrolling over 10 million Americans annually between 1998 and 2006...

We describe recent advances in the empirical analysis of insurance markets. This new research proposes ways to estimate individual demand for insurance and the relationship between prices and insurer costs in the presence of adverse and advantageous selection. We discuss how these models permit...

A major provision of the Affordable Care Act was the creation of Health Insurance Marketplaces, which began operating for the 2014 plan year. Although enrollment initially grew in these markets, enrollment has fallen recently amid insurer exits and rising premiums. To better understand these...

This paper investigates the existence and nature of equilibrium in a competitive insurance market under adverse selection with endogenously determined information structures. Rothschild-Stiglitz (RS) characterized the self-selection equilibrium under the assumption of exclusivity, enforcement of...

Some states have not adopted the Affordable Care Act (ACA) Medicaid expansions due to concerns that the expansions may impair access to care and utilization for those who are already insured. We investigate such negative spillovers using a large panel of Medicare beneficiaries. Across many...