Medicare currently allows beneficiaries to choose between a government-run health plan and a privately- administered program known as Medicare Advantage (MA). Because enrollment in MA is optional, conventional observational estimates of the program's impact are potentially subject to selection...

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...