I take advantage of regulatory and pricing dynamics in Medicare Part D to empirically explore interactions among adverse selection, switching costs, and regulation. I first document novel evidence of adverse selection and switching costs within Part D using detailed administrative data. I then...

This article describes the anatomy of health insurance. It begins by considering the optimal design of health insurance policies. Such policies must make tradeoffs appropriately between risk sharing on the one hand and agency problems such as moral hazard (the incentive of people to seek more...

The United States and other nations rely on consumer choice and price competition among competing health plans to allocate resources in the health sector. A great deal of research has examined the efficiency consequences of adverse selection in health insurance markets, less attention has been...

Individual choice over health insurance policies may result in risk-based sorting across plans. Such adverse selection induces three types of losses: efficiency losses from individuals being allocated to the wrong plans; risk sharing losses since premium variability is increased; and losses from...

This paper uses data on health insurance choices by employees of Harvard University to examine the effect of alternative pricing rules on market equilibrium. In the mid-1990s, Harvard moved from a system of subsidizing more expensive insurance to a system of contributing an equal amount to each...

Revealed-preference measures of willingness to pay (WTP) capture the value of insurance only against the risk that remains when choosing insurance. This paper provides a method to translate observed market WTP and cost curves into an ex-ante value of insurance that can analyze the impact of...

Risk adjustment of payments to health plans is fundamental to regulated competition among private insurers, which serves as the basis of national health policy in many countries. To date, estimation and evaluation of a risk adjustment model has been a two-step process. In a first step, the...

Moral hazard and adverse selection create inefficiencies in private health insurance markets and understanding the relative importance of each factor is critical for policy. We use claims data from a large firm to isolate moral hazard from plan selection. Previous studies have attempted to...

Health insurance markets face two forms of adverse selection problems. On the demand side, adverse selection leads to plan price distortions and inefficient sorting of consumers across health plans. On the supply side, adverse selection creates incentives for plans to inefficiently distort...

Standard policies to correct market power and selection can be misguided when these two forces co-exist. Using a calibrated model of employer-sponsored health insurance, we show that the risk adjustment commonly used by employers to offset adverse selection often reduces the amount of...