Research Database

Randomness in individual discovery disperses productivities, whereas learning from others keeps productivities together. Long-run growth and persistent earnings inequality emerge when these two mechanisms for knowledge accumulation are combined. This paper considers an economy in which those with more useful knowledge can teach others, with competitive markets assigning students to teachers. In equilibrium, students with an ability to learn quickly are assigned to teachers with the most productive knowledge. This sorting on ability implies large differences in earnings distributions conditional on ability, as shown using explicit formulas for the tail behavior of these distributions.

Using simulations from a multicountry neoclassical growth model, we analyze several post-Brexit scenarios. First, the United Kingdom unilaterally imposes tighter restrictions on FDI and trade from other EU nations. Second, the European Union retaliates and imposes the same restrictions on the UK. Finally, the United Kingdom reduces restrictions on other nations during the post-Brexit transition. Model predictions depend crucially on the policy response of multinationals’ investment in technology capital, accumulated know-how from investments in R&D, brands, and organizations used simultaneously in their domestic and foreign operations.

This essay articulates the principles and practices of New Monetarism, our label for a recent body of work on money, banking, payments, and asset markets. We first discuss methodological issues distinguishing our approach from others: New Monetarism has something in common with Old Monetarism, but there are also important differences; it has little in common with Keynesianism. We describe the principles of these schools and contrast them with our approach. To show how it works, in practice, we build a benchmark New Monetarist model, and use it to study several issues, including the cost of inflation, liquidity and asset trading. We also develop a new model of banking.

We build a variation of the neoclassical growth model in which both wealth shocks (in the sense of wealth destruction) and financial shocks to households generate recessions. The model features three mild departures from the standard model: (1) adjustment costs make it difficult to expand the tradable goods sector by reallocating factors of production from nontradables to tradables; (2) there is a mild form of labor market frictions (Nash bargaining wage setting with Mortensen-Pissarides labor markets); (3) goods markets for nontradables require active search from households wherein increases in consumption expenditures increase measured productivity. These departures provide a novel quantitative theory to explain recessions like those in southern Europe without relying on technology shocks.

We develop a pair of risk measures, health and mortality delta, for the universe of life and health insurance products. A life-cycle model of insurance choice simplifies to replicating the optimal health and mortality delta through a portfolio of insurance products. We estimate the model to explain the observed variation in health and mortality delta implied by the ownership of life insurance, annuities including private pensions, and long-term care insurance in the Health and Retirement Study. For the median household aged 51 to 57, the lifetime welfare cost of market incompleteness and suboptimal choice is 3.2% of total wealth.

We develop a new general equilibrium model of asset pricing and asset trading volume in which agents’ motivations to trade arise due to uninsurable idiosyncratic shocks to agents’ risk tolerance. In response to these shocks, agents trade to rebalance their portfolios between risky and riskless assets. We study a positive question — When does trade volume become a pricing factor? — and a normative question — What is the impact of Tobin taxes on asset trading on welfare? In our model, economies in which marketwide risk tolerance is negatively correlated with trade volume have a higher risk premium for aggregate risk. Likewise, for a given economy, we find that assets whose cash flows are concentrated on states with high trading volume have higher prices and lower risk premia. We then show that Tobin taxes on asset trade have a first-order negative impact on ex-ante welfare, i.e., a small subsidy to trade leads to an improvement in ex-ante welfare. Finally, we develop an alternative version of our model in which asset trade arises from uninsurable idiosyncratic shocks to agents’ hedging needs rather than shocks to their risk tolerance. We show that our positive results regarding the relationship between trade volume and asset prices carry through. In contrast, the normative implications of this specification of our model for Tobin taxes or subsidies depend on the specification of agents’ preferences and non-traded endowments.

What shapes the optimal degree of progressivity of the tax and transfer system? On the one hand, a progressive tax system can counteract inequality in initial conditions and substitute for imperfect private insurance against idiosyncratic earnings risk. On the other hand, progressivity reduces incentives to work and to invest in skills, distortions that are especially costly when the government must finance public goods. We develop a tractable equilibrium model that features all of these trade-offs. The analytical expressions we derive for social welfare deliver a transparent understanding of how preference, technology, and market structure parameters influence the optimal degree of progressivity. A calibration for the U.S. economy indicates that endogenous skill investment, flexible labor supply, and the desire to finance government purchases play quantitatively similar roles in limiting optimal progressivity. In a version of the model where poverty constrains skill investment, optimal progressivity is close to the U.S. value. An empirical analysis on cross-country data offers support to the theory.