NBER Publications by Joachim Winter

We study the Medicare Part D prescription drug insurance program as a bellwether for designs of private, non-mandatory health insurance markets that control adverse selection and assure adequate access and coverage. We model Part D enrollment and plan choice assuming a discrete dynamic decision process that maximizes life-cycle expected utility, and perform counterfactual policy simulations of the effect of market design on participation and plan viability. Our model correctly predicts high Part D enrollment rates among the currently healthy, but also strong adverse selection in choice of level of coverage. We analyze alternative designs that preserve plan variety.

Medicare Part D provides prescription drug coverage through Medicare approved plans offered by private insurance companies and HMOs. In this paper, we study the role of current prescription drug use and health risks, related expectations, and subjective factors in the demand for prescription drug insurance. To characterize rational behavior in the complex Part D environment, we develop an intertemporal optimization model of enrollment decisions. We generally find that seniors' choices respond to the incentives provided by their own health status and the market environment as predicted by the optimization model. The proportion of individuals who do not attain the optimal choice is small, but the margin for error is also small since enrollment is transparently optimal for most eligible senio...

Population aging and pension reform will have profound effects on international capital markets. First, demographic change alters the time path of aggregate savings within each country. Second this process may be amplified when a pension reform shifts old-age provision towards more pre-funding. Third, while the patterns of population aging are similar in most counries, timing and initial conditions differ substantially. Hence, to the extent that capital is internationally mobile, population aging will induce capital flows between countries. All three effects influence the rate of return to capital and interact with the demand for capital in production and with labor supply. In order to quantify these effects, we develop a computational general equilibrium model. We feed this multi-country...