Neoclassical life-cycle consumption: a textbook example

Summary.   We present a simple neoclassical life-cycle model in continuous time, in which the effects of endogenous labor supply, uncertain lifetime, and family composition on consumption and income profiles are jointly analyzed. Due to a parsimonious specification, analytical solutions for consumption growth are available for constant intertemporal elasticity of substitution preferences. Without relying on borrowing constraints, the model can generate a hump in the consumption profile, and a comovement of consumption and income during working life. Received: June 9, 1999; revised version: October 4, 1999     

A reconsideration of the problem of social cost: Free riders and monopolists

Summary. One version of the Coase Theorem is, If property rights are fully allocated, competition leads to efficient allocations. This version implies that the public goods problem can be solved by allocating property rights fully. We show that this mechanism is not likely to work well in economies with global externalities because the privatized economy is highly susceptible to strategic behavior: The free-rider problem manifests itself as a complementary monopoly problem in an associated private goods economy. Thus, our work relates the validity of the Coase Theorem to the literature on the incentives for strategic behavior in economies with complementarities. Received: 12 May 1999; revised version: 9 July 1999     

The stand-alone test and decreasing serial cost sharing

Summary. The rule of decreasing serial cost sharing defined in de Frutos [1] over the class of concave cost functions may violate the important stand-alone test. Sufficient conditions for the test to be satisfied are given, in terms of individual rationality as well as coalitional stability. These conditions restrict the shape of the cost function and the distribution of demands. Received: July 29, 1999; revised version: October 4, 1999     

A KKM-result and an application for binary and non-binary choice functions

Summary. By generalizing the classical Knaster-Kuratowski-Mazurkiewicz Theorem, we obtain a result that provides sufficient conditions to ensure the non-emptiness of several kinds of choice functions. This result generalizes well-known results on the existence of maximal elements for binary relations (Bergstrom [4]; Walker [16]; Tian [15]), on the non-emptiness of non-binary choice functions (Nehring [12]; Llinares and Sánchez [9]) and on the non-emptiness of some classical solutions for tournaments (top cycle and uncovered set) on non-finite sets. Received: December 29, 1999; revised version: October 18, 2001     

The government spending and private consumption: a panel cointegration analysis

In this article, whether an increase in government spending will crowd out the private consumption is re-examined. This article augments the empirical literature by extending this issue to panel data. The empirical framework applies the panel cointegration model, dynamic OLS (DOLS), proposed by Kao and Chiang [On the estimation and inference of a cointegrated regression in panel data. Working Paper, Economics Department, Syracuse University, 1999.]. Evidence from 24 OECD countries indicates a significant degree of substitutability between government spending and private consumption when the real disposable income is included, which rejects the permanent income hypothesis. The existence of crowding out renders the Keynesian plea for expansionary fiscal policy unconvincing.     

What do uncertainty-averse decision-makers believe?

Summary. This paper introduces the concept of firm belief, which is proposed as a new epistemic model for a wide class of preferences. In particular, firm beliefs are shown to have the following desirable properties: (i) they are derived from preferences according to a plausible rule of epistemic inference; (ii) they satisfy standard logical properties; and (iii) tractable representations of firm belief are available for all (suitably continuous) biseparable preferences [13, 14], including the Choquet expected utility [30] and maxmin expected utility [16] classes. We also use firm belief to construct a generalization of Nash equilibrium for (two-player) normal form games. Received: December 14, 1999; revised version: February 26, 2001     

An alternative proof of the nonemptiness of the private core

Summary. We focus on the private core [19] of an economy with a finite number of agents with differential information, a continuum of states and an infinite number of commodities. We state a nonemptiness result for the private core and provide a proof based on a fixed-point argument. Received: October 4, 1999; revised version: June 7, 2000     

Learning with noiseless information and payoff-relevant signals

Summary. In models of active learning or experimentation, agents modify their actions to affect the distribution of a signal that provides information about future payoffs. A standard result in the experimentation literature is that agents experiment, if at all, to increase information. This finding is a direct consequence of Blackwell's theorem: one experiment is more informative than another if and only if all expected utility maximizers prefer to observe the first. Blackwell's theorem presupposes, however, that the observed signal only conveys information and does not directly affect future payoffs. Often, however, signals are directly payoff relevant, a phenomenon that we call signal dependence. For example, if a firm is uncertain about its demand and uses today's sales as a signal of tomorrow's demand, then that signal may also directly affect tomorrow's profit if the good is durable or if consumers form consumption habits. Datta, Mirman and Schlee [9] and Bertocchi and Spagat [4] show that, if the signal is payoff relevant, experimentation may indeed reduce information. Here we show that, despite the inapplicability of Blackwell's Theorem, agents always experiment to increase information if the information structure is noiseless: given the true value of the unknown parameter, the signal realization is deterministic. We then apply our framework to analyze Lazear's [16] model of retail clearance sales, a model with both signal dependence and noiseless information. Received: February 19, 1999; revised version: August 11, 1999     

Adverse selection under ignorance

Summary. We examine an adverse selection relationship in which the principal may ignore the ex ante distribution of the agent's types. The principal's behavior is described by a disutility function that covers the standard minimax regret and minimax loss criteria. We show that the incentive compatible and individually rational mechanism, which minimizes the maximal (or the minimal) principal's disutility over a set of priors, requires the efficient agents to realize the corresponding first-best actions and may demand actions lower than the first-best ones from less efficient agents. We also analyze the qualitative differences between the case in which the principal considers regrets and the case in which he considers losses. Received: 19 October 1998; revised version: 9 November 1999     

Unobserved components in an error-correction model of consumption for Southern European countries

In this paper we show how the potential misspecification of the consumption function can be ameliorated by approximating any unmodelled long run variation with an unobserved component in the form of a time-varying trend. This methodology is applied to Greek, Portuguese and Spanish consumption functions during the post-second World war period. The empirical evidence suggests that there are many determinants of long-run consumption in these countries, in addition to income and inflation, and these unobserved long-run effects are captured by a nonstationary stochastic component. The long-run elasticity of consumption with regards to the unobserved component is greater than unity in all countries. First version received: January 1999/Final version received: June 2000     

The equivalence of the Dekel–Fudenberg iterative procedure and weakly perfect rationalizability

Summary. Two approaches have been proposed in the literature to refine the rationalizability solution concept: either assuming that a player believes that with small probability her opponents choose strategies that are irrational, or assuming that their is a small amount of payoff uncertainty. We show that both approaches lead to the same refinement if strategy perturbations are made according to the concept of weakly perfect rationalizability, and if there is payoff uncertainty as in Dekel and Fudenberg [J. of Econ. Theory 52 (1990), 243–267]. For both cases, the strategies that survive are obtained by starting with one round of elimination of weakly dominated strategies followed by many rounds of elimination of strictly dominated strategies. Received: 10 December 1998; revised version: 26 April 1999     

Equilibrium prices in a random exchange economy with dependent agents

Summary. This paper presents a model of a Walrasian exchange economy in which the preferences and endowments of the agents are random. Stochastic interaction among the agents is formally described in terms of dependency neighborhoods. The main result is a characterization of the distribution of market-clearing prices in a large economy. Received: April 23, 1999; revised version: May 6, 1999     

The role of lender behavior in international project finance

Summary. A sovereign borrower seeks to raise funds internationally to finance a fixed-size project, which no single lender can finance alone. Lenders cannot lend more than their endowments, which are private information. A coordination failure arises; therefore, some socially desirable projects may not be financed, even if ex post feasible. There are multiple equilibria, and a conflict exists between lenders about which equilibrium to coordinate on. When endowments are volatile, some lenders prefer an equilibrium in which the project is financed with probability , even if ex post feasible. The government eliminates such equilibria by offering a sufficiently high return, only if endowment volatility is small. Received: June 1, 1999; revised version: December 4, 2000     

Y2K

This paper studies, within a general equilibrium model, the dynamics of Year 2000 (Y2K)-type shocks: anticipated, permanent losses in output whose magnitude can be lessened by investing resources in advance. The implied dynamics replicate three observed characteristics of those triggered by the Y2K bug. (1) Precautionary investment: Investment in solving the Y2K problem begins before the year 2000. (2) Investment delay: Although economic agents have been aware of the Y2K problem since the 1960s, investment did not begin until recently. (3) Investment acceleration: As the new millennium approaches, the amount of resources allocated to solving the Y2K problem increases. In addition, the model predicts that Y2K investment peaks at the end of 1999. Journal of Economic Literature Classification Numbers: E22, E32     

Private consumption behaviour, liquidity constraints and financial deregulation in France: a nonlinear analysis

This paper examines the effect of financial deregulation on consumption expenditure in France during the period 1970–1993. A nonlinear model for consumption which allows for liquidity constraints through a time-varying parameter dependent on a proxy for financial deregulation is estimated using nonlinear instrumental variables. It is concluded that in France financial deregulation has significantly reduced liquidity constraints faced by consumers, allowing a higher percentage of the population to smooth consumption over time. Evidence is also provided that the intertemporal elasticity of substitution is not significantly different from zero at conventional nominal levels of significance. First version received: January 1997/final version received: May 1999     

Coping with ignorance: unforeseen contingencies and non-additive uncertainty

Summary. In real-life decision problems, decision makers are never provided with the necessary background structure: the set of states of the world, the outcome space, the set of actions. They have to devise all these by themselves. I model the (static) choice problem of a decision maker (DM) who is aware that her perception of the decision problem is too coarse, as for instance when there might be unforeseen contingencies. I make a “bounded rationality' assumption on the way the DM deals with this difficulty, and then I show that imposing standard subjective expected utility axioms on her preferences only implies that they can be represented by a (generalized) expectation with respect to a non-additive measure, called a belief function. However, the axioms do have strong implications for how the DM copes with the type of ignorance described above. Finally, I show that some decision rules that have been studied in the literature can be obtained as a special case of the model presented here (though they have to be interpreted differently). Received: December 16, 1999; revised version: March 22, 2000     

Comparing international consumption patterns

When attempting to identify empirical regularities in consumption patterns, their tremendous diversity across countries represents both a major opportunity and challenge. For example, consumers in rich countries devote less than 20% of their budget to food, while this rises to more than 50% in the poorest countries. This paper uses a major new database released in Selvanathan and Selvanathan (Selvanathan EA, Selvanathan S (2003) International Consumption Comparisons: OECD versus LDC. World Scientific, Singapore) to explore several related issues, including the extent to which the consumption basket is diversified and how this changes with income, whether a simple utility-maximising model is capable of explaining the diversity of consumption patterns internationally, the measurement of the extent to which tastes differ across countries, and how the world can be partitioned into groups of countries with minimal within-group heterogeneity of tastes on the basis of the revealed preference of consumers.

Changes in the structure of earnings during the Polish transition

We document changes in the structure of earnings during the economic transition in Poland. We find that inequality in labor earnings increased substantially from 1988 to 1996. A common view is that the reallocation of workers from a public sector with a compressed wage distribution, to a private sector with much higher wage inequality, accounts for the bulk of increased earnings inequality during transition (see, e.g., the models of Aghion and Commander (1999) [Aghion, Philippe, Commander, Simon, 1999. On the dynamics of inequality in the transition. Economics of Transition 7, 275–2898.] and Commander and Tolstopiatenko (1998) [Commander, Simon, Tolstopiatenko, Andrei, 1998. The role of unemployment and restructuring in the transition. In: Commander, Simon (Ed.), Enterprise Restructuring and Unemployment in Models of Transition. The World Bank, Washington, pp. 169–192.]). However, our decomposition of the sources of the increase in inequality suggests that this compositional effect accounts for only 39% of the increase. Fully 52% of the increase is due to the increase in the variance of wages within sectors. That is, earnings inequality within both the private and public sectors grew substantially, and by similar amounts. This is consistent with prior work suggesting that even state-owned enterprises in Poland moved towards competitive wage setting as they restructured (see, e.g., Pinto et al. (1993) [Pinto, Brian, Belka, Marek, Krajewski, Stefan, 1993. Transforming state enterprises in Poland: evidence on adjustment by manufacturing firms. Brookings papers on Economic Activity, 213-70.] Commander and Dhar (1998) [Commander, Simon, Dhar, Sumana, 1998. Enterprises in the Polish transition. In Simon Commander (Ed.), Enterprise Restructuring and Unemployment in Models of Transition. The World Bank, Washington, pp. 109-142.]).A substantial part of the increase in earnings inequality was between group, due largely to increased education premiums. However, changes in inequality within education–experience–gender groups account for about 60 percent of the increase in overall earnings inequality. The increases in within-group inequality were very different across skill groups, with much larger increases for highly educated workers. These patterns hold in both the private and public sectors, although increases in education premiums were somewhat greater in the private sector.     

Further issues in forecasting primary energy consumption

The series of papers by Marchetti [8, 9, 10] and Graham and Senge [4] (published in this journal between 1977 and 1980) represents a useful alternative approach to the problems of energy demand forecasting and primary energy substitution. The learning system approach seems a most appropriate investigative framework, given the aggregated treatment of the energy supply-demand system. It is also interesting for its attempt to establish a link between the structure of the primary energy markets and the 50–60 year cycles of basic innovations.This paper seeks to illustrate further conclusions from the reported research findings, by considering additional energetic criteria. These additional criteria—energy concentration (or quality) and energy accessibility—appear to reinforce the linkage between innovation waves and primary energy substitution patterns, though we modify the interpretation placed on this connection. Furthermore, the additional criteria lead to alternative conclusions about future energy supply, namely that previously discarded energy sources may be revisited and may retain some of their earlier market share.     

Optimal investment and consumption with return predictability and execution costs

We provide a closed-form solution to an optimal investment and consumption problem for a constant absolute risk aversion (CARA) agent, who faces execution costs when trading correlated risky assets with return predictability. The optimal investment strategy indicates that the agent should trade gradually toward a dynamic aim portfolio, which is an adjusted Merton portfolio with modifications to account for the persistence of the return-predicting signals and the execution costs. The optimal consumption strategy is quadratic in the return-predicting signals and linear in the agent's wealth. Our numerical studies show that the execution costs diminish the importance of asset return predictability on the agent's optimal investment strategy, thereby confirming the conjecture raised by Liu (2004). In addition, the presence of the intermediate consumption leads to a more aggressive aim portfolio than the case without consumption.