Research Database

We provide a theoretical treatment of temporal aggregation in models that exhibit long-term endogenously-generated steady growth; hence generalizing our previous analysis (Econometrica 62, 1994, pp. 635–56). We introduce the property of steady-growth invariance—that the long-term growth of the continuous-time economy not be affected by the discretization—which imposes consistency restrictions on the joint formulation of preferences and stock accumulation of the discrete-time approximation. We establish, under mild conditions, these restrictions in the form of necessary and sufficient conditions on the discretization.

In a general equilibrium setting, we study versions of the proposal to pay interest on reserves at the market rate. We argue that the proposal makes the demand for total reserves indeterminate whether interest is paid on total reserves or on required reserves only. One consequence is that tax financing of the proposal gives rise to a continuum of equilibria, equilibria which differ in real returns and consumption allocations. Another consequence is that an attempt to finance the proposal through earnings on the central bank’s portfolio either gives rise to an equilibrium with a zero nominal interest rate or fails to give rise to an equilibrium.

We modify a standard SIR epidemiological model to allow for testing and asymptomatic agents. We explore cross country variation's ability to allow for identification of key parameters of the model: the fatality rate and the evolution over time of the normalized transmission rate. We first show that as long as tests are applied only to agents who exhibit symptoms, those parameters cannot be identified. We briefly discuss which additional information may allow for identification. Finally, we also describe conditions under which the normalized transmission rate can be computed with very high accuracy, and how cross country evidence can be used to evaluate the effect of lockdowns on evolution of the effective transmission rate over time.

In a finite-trader version of the Diamond-Dybvig (1983) model, the symmetric, ex-ante efficient allocation is implementable by a direct mechanism (i.e., each trader announces the type of his own ex-post preference) in which truthful revelation is the strictly dominant strategy for each trader. When the model is modified by formalizing the sequential-service constraint (cf. Wallace, 1988), the truth-telling equilibrium implements the symmetric, ex-ante efficient allocation with respect to iterated elimination of strictly dominated strategies.

Consider an economy in which various types of labor are used to produce consumption, but not all types of labor are useful for upgrading the stock of organization capital–that is, for replacing old projects with more productive new projects. When news induces consumers to want to save more, low-quality projects are destroyed across all sectors of the economy, even though the economy is set to increase its stock of new projects. Labor that can be used to create new projects becomes more expensive and labor that cannot becomes cheap. Average wages may not change at all, and the employment of workers who cannot invest in new projects will decline. If physical capital complements the inputs of these workers, investment in physical capital tends to move together with their employment. These results are derived analytically for a prototype economy that has the essential ingredients of empirically relevant equilibrium models of firm heterogeneity.

This paper puts forward a method of policy simulation with an existing macroeconometric model under the maintained assumption that individuals form their expectations rationally. This new simulation technique grows out of Lucas' criticism that standard econometric policy evaluation permits policy rules to change but doesn't allow expectations mechanisms to respond as economic theory predicts they will. This technique is applied to versions of the St. Louis Federal Reserve model and the FRB-MIT-Penn model to simulate the effects of different constant money growth policies. I shall briefly summarize the current practice of policy evaluation and the Lucas critique in the first section. The second section includes an explanation of the method I propose. The third section includes the two illustrative applications. In the conclusion, I cannot resist the temptation to offer some opinions about the use and usefulness of econometric models.

This paper is motivated by a variety of empirical observations on the comovements of currency velocity, inflation, and the relative size of the “credit services” sector. By the credit services sector we mean the part of banking and credit sector which provides alternative means of transactions to using currency as well as other services which help people economize on currency. We incorporate the credit services sector into a monetary growth model. Our model makes two specific and new contributions. The first is to show that direct quantitative evidence on the welfare cost of low inflation using measures of the relative size of an appropriately defined credit services sector for the U.S.—essentially the cost incurred by banks and credit unions in providing demand deposit and credit card services—is consistent with the welfare cost measured using an estimated money demand curve following the classic analysis of Bailey (1956) and the more recent analysis of Lucas (1993). Both of these measures amount to about 0.5 percent of GNP. The second contribution is in providing welfare cost of inflation estimates over a range of inflation rates which have some new features. We find that the total welfare cost of inflation remains bounded at about 5 percent of consumption.

This thesis consists of a series of essays on the theory of exchange under uncertainty. The first essay examines the welfare implications of futures markets in the context of complete markets for contingent claims. It is shown that in a C-good, S-state world the equilibrium allocations resulting from the operation of pre-state noncontingent futures markets and post-state spot markets may be Pareto optimal. This proposition turns on the fact that a futures contract can be interpreted as a security whose state-specific return is the post-state spot price. If the matrix of spot prices has rank S, then, with futures and spot markets, agents can achieve the same allocations over states as with complete markets for contingent claims.

This paper studies the relationship between the existence and optimality of a monetary steady-state and the nonoptimality of nonmonetary steady-states. We construct a sequence of stationary overlapping generations economies with longer and longer lived generations in which all agents maximize a discounted sum of utilities with a common discount rate. Under some assumptions the following result is established: If the discount rate is greater (less) than the population growth rate, then eventually every nonmonetary steady-state is optimal (non-optimal) and a monetary steady-state does not exist (exists and is optimal).

The qualitative dynamics of a discrete time version of a deterministic, continuous time, nonlinear macro model formulated by Haavelmo are fully characterized. The methods of symbolic dynamics and ergodic theory are shown to provide a simple, effective means of analyzing the behavior of the resulting one-parameter family of first-order, deterministic, nonlinear difference equations. A complex periodic and random "aperiodic" orbit structure dependent on a key structural parameter is present, which contrasts with the total absence of such complexity in Haavelmo's continuous time version. Several implications for dynamic economic modelling are discussed.

This study estimates the effects of allowing bank holding companies (BHCs) to enter several lines of financial business not now permitted. A simulation technique is used to estimate the risk and return of hypothetical financial corporations after merger between a BHC and a large firm in each of these industries: securities, real estate, life insurance, property and casualty insurance, and insurance agencies. The study concludes that a merger between a BHC and a life insurance company may decrease the probability of bankruptcy for the merged firm relative to the BHC alone. This result does not hold true, however, for BHC mergers with firms in the other industries. In particular, BHC mergers with securities or real estate firms are found to increase the probability of bankruptcy.

In this paper, we build a model of the transition following large-scale economic reforms that predicts both a substantial drop in output and a prolonged pause in physical investment as the initial phase of the optimal transition following the reform. We model reform as a change in policy which induces agents to close existing enterprises using old technologies of production and to open up new enterprises adopting new technologies of production. The central idea of our paper is that it is costly to close old enterprises and open new enterprises because, in doing so, information capital built up about old enterprises is lost and time must pass before information capital about new enterprises can be acquired. Thus, an acceleration of the pace of industry evolution leads in the short run to a net loss of information capital, a drop in productivity, a recession, and a fall in physical investment. We calibrate our model of industry evolution, information capital, and transition to match micro data on industry evolution in the United States and macro data from the United States, Japan, and the former communist countries of Europe. We find that the loss of information capital that accompanies a major acceleration in the pace of industry evolution in an economy leads initially to a decade of recession and a five year pause in physical investment before the benefits of reform are realized.

We analyze the secular decline in interstate migration in the United States between 1991 and 2011. Gross flows of people across states are about 10 times larger than net flows, yet have declined by around 50 percent over the past 20 years. We argue that the fall in migration is due to a decline in the geographic specificity of returns to occupations, together with an increase in workers’ ability to learn about other locations before moving there, through information technology and inexpensive travel. These explanations find support in micro data on the distribution of earnings and occupations across space and on rates of repeat migration. Other explanations, including compositional changes, regional changes, and the rise in real incomes, do not fit the data. We develop a model to formalize the geographic-specificity and information mechanisms and show that a calibrated version is consistent with cross-sectional and time-series patterns of migration, occupations, and incomes. Our mechanisms can explain at least one-third and possibly all of the decline in gross migration since 1991.

This study describes recent attempts to solve what Lucas has called the "problem of economic development"—the problem of accounting for the great disparity in per-capita output across countries. The study examines a number of economic development theories, including the neoclassical theory of growth, which relies on cross-country differences in physical capital per person to explain the disparity, and newer theories, which stress cross-country differences in human capital, or education. It is argued that these models cannot account for observed per-capita output diversity. More promising theories are those that stress differences in incentives for entrepreneurs to create businesses (i.e., business capital) and adopt new technologies.

Both Chile and Mexico experienced severe economic crises in the early 1980s, yet Chile recovered much faster than Mexico. This study analyzes four possible explanations for this difference and rules out three, explanations based on money supply expansion, real wage and real exchange rate declines, and foreign debt overhangs. The fourth explanation is based on government policy reforms in the two countries. Using growth accounting and a calibrated growth model, the study determines that the only policy reforms promising as explanations are those that primarily affect total factor productivity, or how inputs are used, not the inputs themselves. Interpreting historical evidence with economic theory, the study concludes that the crucial difference between Chile and Mexico in the 1980s and 1990s is earlier government policy reforms in Chile, particularly reforms in policies affecting the banking system and bankruptcy procedures.

The existence of fixed points for monotone maps on spaces of measures is established. The case of monotone Markov processes is analyzed and a uniqueness and global stability condition is developed. A comparative statics result is presented and the problem of approximation to the invariant distribution is discussed. The conditions of the theorems are verified for the cases of Optimal Stochastic Growth and Industry Equilibrium.

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.

In this paper we analyze the rate of convergence to a balanced path in a class of endogenous growth models with physical and human capital. We show that such rate depends locally on the technological parameters of the model, but does not depend on those parameters related to preferences. This result stands in sharp contrast with that of the one-sector neoclassical growth model, where both preferences and technologies determine the speed of convergence to a steady-state growth path.

This paper, originally published in the fall 1979 Quarterly Review, explains why unfettered markets cannot determine a price at which the currency of one country exchanges for that of another. In effect, any price will work—something which is not true in other markets. The paper then argues that the only feasible regimes for these special markets are floating exchange rates with capital controls or fixed exchange rates with monetary and budget policy coordination.

AK growth models predict that permanent changes in government policies affecting investment rates should lead to permanent changes in a country’s GDP growth. Charles Jones (1995) sees no evidence for this prediction in data for 15 OECD countries after World War II: rates of investment, especially for equipment, have risen while GDP growth rates have not. This article provides evidence supporting the AK models’ prediction. Data back to the 19th century show a strong positive relationship between investment rates and growth rates and short-lived deviations from trends. A strong positive relationship also exists between average rates of investment and growth in postwar data for a large cross-section of countries. To account for the short-run deviations in rates that Jones highlights, the model he used is extended to allow policies to affect not only investment/output ratios but also capital/output ratios and labor/leisure decisions.