Research Database

Does the pattern of social connections between individuals matter for macroeconomic outcomes? If so, where do these differences come from and how large are their effects? Using network analysis tools, we explore how different social network structures affect technology diffusion and thereby a country's rate of growth. The correlation between high-diffusion networks and income is strongly positive. But when we use a model to isolate the effect of a change in social networks, the effect can be positive, negative, or zero. The reason is that networks diffuse ideas and disease. Low-diffusion networks have evolved in countries where disease is prevalent because limited connectivity protects residents from epidemics. But a low-diffusion network in a low-disease environment needlessly compromises the diffusion of good ideas. In general, social networks have evolved to fit their economic and epidemiological environment. Trying to change networks in one country to mimic those in a higher-income country may well be counterproductive.

We propose a simple method to help researchers develop quantitative models of economic fluctuations. The method rests on the insight that many models are equivalent to a prototype growth model with time-varying wedges which resemble productivity, labor and investment taxes, and government consumption. Wedges corresponding to these variables—efficiency, labor, investment, and government consumption wedges—are measured and then fed back into the model in order to assess the fraction of various fluctuations they account for. Applying this method to U.S. data for the Great Depression and the 1982 recession reveals that the efficiency and labor wedges together account for essentially all of the fluctuations; the investment wedge plays a decidedly tertiary role, and the government consumption wedge, none. Analyses of the entire postwar period and alternative model specifications support these results. Models with frictions manifested primarily as investment wedges are thus not promising for the study of business cycles. (See Additional Material for a response to Christiano and Davis (2006).)

No abstract available.

Intuitively, a patient trader should be able to make his trading partners compete to reveal whatever information is relevant to their transactions with him. This possibility is examined in the context of a model resembling that of Gale (1986). The main result is that, under assumptions having to do with asset structure and spanning, incentive-compatible elicitation of trading partners’ knowledge is feasible.

A classic result in the theory of implicit contract models with asymmetric information is that “underemployment” results if and only if leisure is an inferior good. We introduce household production into the standard implicit contract model and show that we can have underemployment at the same time that leisure is a normal good.

In this paper we develop a model in which a country faces a balance of payments crisis if constraints on its international borrowing bind. We use the model to describe the dynamics of the trade balance, capital account, and balance of payments of a country that borrows to finance consumption following sweeping macroeconomic and structural reforms and then hits constraints on its international borrowing. We compare the predictions of this theoretical example with events in Mexico from 1987 through 1995.

Our thesis is that poor countries are poor because they employ arrangements for which the equilibrium outcomes are characterized by inferior technologies being used, and being used inefficiently. In this paper, we analyze the consequences of one such arrangement. In each industry, the arrangement enables a coalition of factor suppliers to be the monopoly seller of its input services to all firms using a particular production process. We find that the inefficiencies associated with this monopoly arrangement can be large. Whereas other studies have found that inefficiencies induced by monopoly are at most a few percent of output, we find that eliminating this monopoly arrangement could well increase output by roughly a factor of 3 without any increase in inputs.

We examine entry across 113 national markets in 16 different industries using a comprehensive data set of French manufacturing firms. The data are unique in indicating how much each firm exports to each destination. Looking across all manufacturers: (1) Firms differ substantially in export participation, with most selling only at home; (2) The number of firms selling to multiple markets falls off with the number of destinations with an elasticity of –2.5; (3) Decomposing French exports to each destination into the size of the market and French share, variation in market share translates nearly completely into firm entry while about 60 percent of the variation in market size is reflected in firm entry. Looking within each of 16 industries we find little variation in these patterns. We propose that any successful model of trade and market structure must confront these facts.

The Pareto-like tail of the size distribution of firms can arise from random growth of productivity or stochastic accumulation of capital. If the shocks that give rise to firm growth are perfectly correlated within a firm, then the growth rates of small and large firms are equally volatile, contrary to what is found in the data. If firm growth is the result of many independent shocks within a firm, it can take hundreds of years for a few large firms to emerge. This paper describes an economy with both types of shocks that can account for the thick-tailed firm size distribution, high entry and exit rates, and the relatively young age of large firms. The economy is one in which aggregate growth is driven by the creation of new products by both new and incumbent firms. Some new firms have better ideas than others and choose to implement those ideas at a more rapid pace. Eventually, such firms slow down when the quality of their ideas reverts to the mean. As in the data, average growth rates in a cross section of firms will appear to be independent of firm size, for all but the smallest firms.