Research Database

In this paper we describe how to optimally design a disability insurance system. The key friction in the model is imperfectly observable disability. We solve a dynamic mechanism design problem and provide a theoretical and numerical characterization of the social optimum. We then propose a simple tax system that implements an optimal allocation as a competitive equilibrium. The tax system that we propose includes only taxes and transfers that are similar to those already present in the U.S. tax code: a savings tax and an asset-tested transfer program. Using a numerical simulation, we compare our optimal disability system to the current disability system. Our results suggest a significant welfare gain from switching to an optimal system.

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 theory of economic growth in an urban environment. We show how the urban structure is the margin that eliminates local increasing returns to yield constant returns to scale in the aggregate, thereby implying a city size distribution that is well described by a power distribution with coefficient one: Zipf’s Law. Under strong assumptions our theory produces Zipf’s Law exactly. More generally, it produces the systematic deviations from Zipf’s Law observed in the data, namely, the underrepresentation of small cities and the absence of very large ones. In these cases, the model identifies the standard deviation of industry productivity shocks as the key element determining dispersion in the city size distribution. We present evidence that the dispersion of city sizes is consistent with the dispersion of productivity shocks in the data.

Models with sticky prices predict that monetary policy changes will affect relative prices and relative quantities in the short run because some prices are more flexible than others. In U.S. micro data, the degree of price stickiness differs dramatically across consumption categories. This study exploits that diversity to ask whether popular measures of monetary shocks (for example, innovations in the federal funds rate) have the predicted effects. The study finds that they do not. Short-run responses of relative prices have the wrong sign. And monetary policy shocks seem to have persistent effects on both relative prices and relative quantities, rather than the transitory effects one would expect from differences in price flexibility across goods. The findings reject the joint hypothesis that the sticky-price models typically employed in policy analysis capture the U.S. economy and that commonly used monetary policy shocks represent exogenous shifts.

Economists have offered many theories for the U.S. Great Depression, but no consensus has formed on the main forces behind it. Here we describe and demonstrate a simple methodology for determining which theories are the most promising. We show that a large class of models, including models with various frictions, are equivalent to a prototype growth model with time-varying efficiency, labor, and investment wedges that, at least on face value, look like time-varying productivity, labor taxes, and investment taxes. We use U.S. data to measure these wedges, feed them back into the prototype growth model, and assess the fraction of the fluctuations in 1929–39 that they account for. We find that the efficiency and labor wedges account for essentially all of the decline and subsequent recovery. Investment wedges play, at best, a minor role.

This article investigates U.S. interbank relationships before the Civil War using previously unknown data for Pennsylvania banks from 1851 to 1859 that disaggregate the amounts due from other banks by debtor bank. It finds that country banks, banks outside of Philadelphia and Pittsburgh, dealt almost exclusively with financial center banks. Most had a large, highly stable relationship with a single correspondent bank. The location of a country bank’s correspondent was consistent with trade patterns, particularly railroad and canal linkages. Philadelphia banks, in contrast, did not establish correspondent-type banking relationships. Further, Philadelphia’s correspondent banking market was not highly concentrated, and entry was easy.

Does the extent of competitive pressure industries face influence their productivity? We study a natural experiment conducted in the iron ore industry as a result of the collapse in world steel production in the early 1980s. For iron ore producers, whose only market is the steel industry, this collapse was an exogenous shock. The drop in steel production differed dramatically by region: it fell by about a third in the Atlantic Basin but only very little in the Pacific Basin. Given that the cost of transporting iron ore is very high relative to its mine value, Atlantic iron ore producers faced a much greater increase in competitive pressure than did Pacific iron ore producers. In response to the crisis, most Atlantic iron ore producers doubled their labor productivity; Pacific iron ore producers experienced few productivity gains.

This study describes how the U.S. government measures real consumption growth and how it tries to take account of a complicating factor: that the goods and services offered to consumers change over time; new products are introduced and old products are improved. The 1996 Boskin Commission critique of this government methodology is described, along with the changes made in response to that critique. Also described is recent research related to how real consumption growth should be measured in the presence of new and better products.