Research Database

Many view the period after the Second Industrial Revolution as a paradigmatic example of a transition to a new economy following a technological revolution and conjecture that this historical experience is useful for understanding other transitions, including that after the Information Technology Revolution. We build a model of diffusion and growth to study transitions. We quantify the learning process in our model using data on the life cycle of U.S. manufacturing plants. This model accounts quantitatively for the productivity paradox, the slow diffusion of new technologies, and the ongoing investment in old technologies after the Second Industrial Revolution. The main lesson from our model for the Information Technology Revolution is that the nature of transition following a technological revolution depends on the historical context: transition and diffusion are slow only if agents have built up through learning a large amount of knowledge about old technologies before the transition begins.

Typical incomplete markets models in international economics make two assumptions. First, households are not able to fully insure themselves against country-specific shocks. Second, there is a representative household within each country, so that households are fully insured against idiosyncratic shocks. We assume instead that cross-household risk-sharing is limited within countries, but cross-country risk-sharing is complete. We consider two types of limited risk-sharing: domestically incomplete markets (DI) and private information-Pareto optimal (PIPO) risk-sharing. We show that the models imply distinct restrictions between the cross-sectional distributions of consumption and real exchange rates. We evaluate these restrictions using household-level consumption data from the United States and the United Kingdom. We show that the PIPO restriction fits the data well when households have a coefficient of relative risk aversion of around 5. The analogous restrictions implied by the representative agent model and the DI model are rejected at conventional levels of significance.

I develop an asset-pricing model in which financial assets are valued for their liquidity—the extent to which they are useful in facilitating exchange—as well as for being claims to streams of consumption goods. The implications for average asset returns, the equity-premium puzzle and the risk-free rate puzzle, are explored in a version of the model that nests the work of Mehra and Prescott (1985).

A distinction is drawn between outside money—money that is either of a fiat nature or backed by some asset that is not in zero net supply within the private sector—and inside money, which is an asset backed by any form of private credit that circulates as a medium of exchange.

We investigate how trading frictions in asset markets affect portfolio choices, asset prices and efficiency. We generalize the search-theoretic model of financial intermediation of Duffie, Gârleanu and Pedersen (2005) to allow for more general preferences and idiosyncratic shock structure, unrestricted portfolio choices, aggregate uncertainty and entry of dealers. With a fixed measure of dealers, we show that a steady-state equilibrium exists and is unique, and provide a condition on preferences under which a reduction in trading frictions leads to an increase in the price of the asset. We also analyze the effects of trading frictions on bid-ask spreads, trade volume and the volatility of asset prices, and find that the asset allocation is constrained-inefficient unless investors have all the bargaining power in bilateral negotiations with dealers. We show that the dealers’ entry decision introduces a feedback that can give rise to multiple equilibria, and that free-entry equilibria are generically inefficient.

Most economic activity occurs in cities. This creates a tension between local increasing returns, implied by the existence of cities, and aggregate constant returns, implied by balanced growth. To address this tension, we develop a general equilibrium theory of economic growth in an urban environment. In our theory, variation in the urban structure through the growth, birth, and death of cities is the margin that eliminates local increasing returns to yield constant returns to scale in the aggregate. We show that, consistent with the data, the theory produces a city size distribution that is well approximated by Zipf’s Law, but that also displays the observed systematic under-representation of both very small and very large cities. Using our model, we show that the dispersion of city sizes is consistent with the dispersion of productivity shocks found in the data.

Monetary policy instruments differ in tightness—how closely they are linked to inflation—and transparency—how easily they can be monitored. Tightness is always desirable in a monetary policy instrument; when is transparency? When a government cannot commit to follow a given policy. We apply this argument to a classic question: Is the exchange rate or the money growth rate the better monetary policy instrument? We show that if the instruments are equally tight and a government cannot commit to a policy, then the exchange rate’s greater transparency gives it an advantage as a monetary policy instrument.

Why do growth and net exit rates of establishments decline with size? What determines the size distribution of establishments? This paper presents a theory of establishment dynamics that simultaneously rationalizes the basic facts on economy-wide establishment growth, net exit, and size distributions. The theory emphasizes the accumulation of industry-specific human capital in response to industry-specific productivity shocks. It predicts that establishment growth and net exit rates should decline faster with size and that the establishment size distribution should have thinner tails in sectors that use human capital less intensively or physical capital more intensively. In line with the theory, the data show substantial sectoral heterogeneity in U.S. establishment size dynamics and distributions, which is well explained by variation in physical capital intensity.

Theoretical advances in macroeconomics made in the last three decades have had a major influence on macroeconomic policy analysis. Moreover, over the last several decades, the United States and other countries have undertaken a variety of policy changes that are precisely what macroeconomic theory of the last 30 years suggests. The three key developments that have shaped macroeconomic policy analysis are the Lucas critique of policy evaluation due to Robert Lucas, the time inconsistency critique of discretionary policy due to Finn Kydland and Edward Prescott, and the development of quantitative dynamic stochastic general equilibrium models following Finn Kydland and Edward Prescott.