Representing complete and incomplete subjective linear preferences on random numbers

We show that preferences on random numbers which satisfy certain natural properties can be represented, in the setting of topological vector spaces, by a suitable family of continuous previsions which is, in a sense, unique. Moreover, for most commonly used spaces of random numbers, we establish that one can derive these preferences, via an expectation operator, from a suitable family of probabilities (whether or not finitely additive). Mathematics Subject Classification (2000): 06A06, 62C05, 91B06 Journal of Economic Literature Classification: D11, D81     

Reduced Form Auctions Revisited

This note uses the Theorem of the Alternative to prove new results on the implementability of general, asymmetric auctions, and to provide simpler proofs of known results for symmetric auctions. The tradeoff is that type spaces are taken to be finite.     

Human Capital and Growth Cycles

This paper studies the dynamic interaction between human capital accumulation and economic growth. Capital market imperfections and an indivisibility in human capital investment prevent poor agents from accumulating skills, the acquisition of which positively affects technological progress. More productive technologies in turn require more sophisticated qualification and involve higher training costs. The equilibrium dynamics can be characterized by the joint evolution of productivity growth, the schooling costs, and the income distribution. Under our assumptions, individual incomes follow a non-linear Markov chain. This non-linearity generates endogenous fluctuations of schooling activities and the rate at which productivity improvements occur. We thank an anonymous referee for many helpful suggestions. Support from the German Research Foundation (DFG) under grant KA1519/2-2 is gratefully acknowledged.     

Effective regulation versus tacit collusion in the long-distance market: an empirical analysis

Regulatory decisions often must be made in an atmosphere of uncertainty, and arguments presented by the affected parties frequently add to, rather than resolve, that uncertainty. Here, we examine several of the deregulatory decisions affecting the long-distance market that were rendered by the FCC over the two-decade period following the divestiture of AT&T. Our purpose is to provide empirical evidence relevant to some of the arguments regarding market conditions that were presented during that period. Findings suggest that some of the more prominent allegations are not supported by the data.      

On a clear day you might see an environmental Kuznets curve

We shed some new light on the Environmental Kuznets curve (EKC) and show how it can be viewed as a particular form of equilibrium relationship, where technology and preference parameters determine the shape of the curve. In contrast to most of the literature on the EKC, we estimate a theoretically consistent model on long-run data (Swedish sulfur emission, covering the period 1900–2002). Furthermore, we test and date structural change. The model suggests four regimes, 1900–1918, 1919–1933, 1934–1967 and 1968–2002, generating four rather different patterns for pollution over time. The policy-conclusions are consonant with Pearce’s general view about the EKC: there is no theoretical presumption that it has an inverted U shape, nor should any country try to “grow out of the environmental problems” without analyzing the benefits and costs of so doing.     

Recursive utility with unbounded aggregators

A new framework is presented for the study of the existence and uniqueness of solutions to the Koopmans’ equation in the unbounded case, that is based on the contraction mapping approach. In the bounded below case with bounded consumption streams, uniqueness of the solution in the whole class of weak-star continuous utility functions is obtained. When the aggregator is unbounded below and/or consumption streams are unbounded, existence of a weak-star continuous solution is shown, and a simple criterium to check the sufficient conditions for existence is provided. Juan Pablo Rincón-Zapatero and Carlos Rodríguez-Palmero gratefully acknowledge financial support by the Ministerio de Educación y Ciencia and FEDER funds under Research Projects MTM2005-06534 and SEJ2005-08709/ECON, respectively, and by Consejería de Educación de la Junta de Castilla y León under Research Projects VA99/04 and VA017B05, respectively. This paper has substantially benefited from the comments of an anonymous referee. Particular and special thanks are due to Robert Becker for his very helpful comments and valuable suggestions.     

Aid, Agriculture and Poverty in Developing Countries

The authors make two contributions to the debate on aid‐effectiveness, illustrating that for impact on poverty what matters is not just the level but also the composition and stability of aid. One specific implication of this for aid policy is that aid most effectively reduces poverty if it supports public (and other) expenditures which are supportive of agricultural development. Regression analysis confirms that these are not only direct expenditure on agriculture, but also on education and infrastructure, and military expenditure has a negative impact. Three factors appear to be particularly conducive to the development of stable pro‐poor expenditure patterns (and in particular pro‐agriculture expenditure patterns). These are expenditure strategies which protect the poor against risk, the development of stable relations between governments and aid donors, and long‐term political commitment to pro‐poor strategies by government. The argument is pursued partly by panel‐data econometric analysis of developing countries as a whole, and partly by case studies of sustained and non‐sustained green revolutions in heavily aid‐dependent countries in Africa.     

Stock-flow matching and the performance of the labor market

We estimate outflow equations for vacancies and unemployed workers in Britain, departing from the stock-based analysis of matching in two ways. First, we deal with the temporal aggregation problem that arises when discrete time data are used to describe continuous time processes. Second, we allow for a stock-flow matching mechanism in which the stock of traders on one side of the market matches with the flow of traders on the other side. Our estimates are in line with the predictions of stock-flow matching in terms of higher exit rates of flows and of matching combinations between labor market stocks and flows. Furthermore, employer search effectiveness did not seem to decline between the 1960s and the 1990s. Nevertheless, some deterioration in worker search effectiveness is detected, however less severe than that implied by previous, stock-based work.     

On the impact of leverage constraints on asset prices and trading volume

Abstract. Researchers have used stylized facts on asset prices and trading volume in stock markets (in particular, the mean reversion of asset returns and the correlations between trading volume, price changes and price levels) to support theories where agents are not rational expected utility maximizers. This paper shows that this empirical evidence is in fact consistent with a standard infinite horizon – perfect information – expected utility economy where some agents face leverage constraints similar to those found in todays financial markets. In addition, and in sharp contrast to the theories above, we explain some qualitative differences that are observed in the price-volume relation on stock and on futures markets. We consider a continuous-time economy where agents maximize the integral of their discounted utility from consumption under both budget and leverage constraints. Building on the work by Vila and Zariphopoulou (1997), we find a closed form solution, up to a negative constant, for the equilibrium prices and demands in the region of the state space where the constraint is non-binding. We show that, at the equilibrium, stock holdings volatility as well as its ratio to stock price volatility are increasing functions of the stock price and interpret this finding in terms of the price-volume relation. We would like to thank the editor and two anonimous referees for valuable substantive comments. Our gratitude also to Franklin Allen, Kerry Back, Domenico Cuoco, Xavier Freixas, Sanford Grossman, Michel Habib, Lutz Hendricks, Richard Kihlstrom, Fernando Restoy, Mary Thomson, Jean-Luc Vila, participants to seminars at Birkbeck College, Carnegie-Mellon, Columbia, ESSEC, HEC, IAE, INSEAD, London Business School, London School of Economics, McGill, Michigan, National University of Singapore, Pompeu Fabra, North Carolina, Washington-St-Louis, Wharton, the Jornadas de Economía Financiera BBV, and the Meetings of the Society for Economic Dynamics and Control and the American Finance Association. Special thanks are due to Süleyman Basak for his enthusiastic support and many helpful suggestions. The usual disclaimer applies. We gratefully acknowledge the support of the BBV and Caja de Madrid Foundations and CREF (both authors) and of the Spanish Ministry of Education under DGICYT grant no. PB93-0388 (first author).