Efficiency and prices in economies of overlapping generations

In a general economy of overlapping generations, I introduce a notion of uniform inefficiency, corresponding to the occurrence of a Pareto improvement with a small uniform destruction of resources [G. Debreu, The coefficient of resource utilization, Econometrica 19 (1951) 273-292]. I provide a necessary and sufficient condition for uniform inefficiency in terms of prices at a competitive equilibrium: an allocation is uniformly inefficient if and only if the relative price of the aggregate endowment in a given period into the aggregate endowment up to that period does not vanish over periods of trade, a sort of Modified Cass Criterion [D. Cass, On capital overaccumulation in the aggregative neoclassical model of economic growth: a complete characterization, J. Econ. Theory 4 (1972) 200-223]. Minimal assumptions on fundamentals are needed for such a complete characterization. Furthermore, proofs reduce to simple and short direct arguments. Finally, I verify that uniform inefficiency is preserved under perturbations, a property that might fail for the canonical notion of inefficiency. Remarkably, an allocation is uniformly inefficient if and only if a non-vanishing redistribution, like a social security mechanism, is welfare improving.     

A characterization of inefficiency in stochastic overlapping generations economies

In this paper, we provide a characterization of interim inefficiency in stochastic economies of overlapping generations. With respect to the established body of results in the literature, we allow for sequentially incomplete markets and we remove the hypothesis of two-period horizons, by considering longer, though uniformly bounded, horizons for generations. The characterization exploits a suitably Modified Cass Criterion, based entirely on observable prices and independent of the length of the horizons of generations. For sequentially incomplete markets, we introduce a notion of unambiguous inefficiency, separating the inefficient intertemporal allocation of resources from incomplete risk-sharing. Unambiguous inefficiency reduces to inefficiency when markets are sequentially complete. Furthermore, our analysis shows that the hypothesis of two-period horizons is purely heuristic in establishing a criterion for inefficiency.     

Consumption dynamics in general equilibrium: A characterisation when markets are incomplete

We introduce a methodology for analysing infinite horizon economies with two agents, one good, and incomplete markets. We provide an example in which an agent's equilibrium consumption is zero eventually with probability one even if she has correct beliefs and is marginally more patient. We then prove the following general result: if markets are effectively incomplete forever then on any equilibrium path on which some agent's consumption is bounded away from zero eventually, the other agent's consumption is zero eventually—so either some agent vanishes, in that she consumes zero eventually, or the consumption of both agents is arbitrarily close to zero infinitely often. Later we show that (a) for most economies in which individual endowments are finite state time homogeneous Markov processes, the consumption of an agent who has a uniformly positive endowment cannot converge to zero and (b) the possibility that an agent vanishes is a robust outcome since for a wide class of economies with incomplete markets, there are equilibria in which an agent's consumption is zero eventually with probability one even though she has correct beliefs as in the example. In sharp contrast to the results in the case studied by Sandroni (2000) [29] and Blume and Easley (2006) [8] where markets are complete, our results show that when markets are incomplete not only can the more patient agent (or the one with more accurate beliefs) be eliminated but there are situations in which neither agent is eliminated.     

The existence, uniqueness, and optimality of the terminal wealth depletion time in life-cycle models of saving under uncertain lifetime and borrowing constraint

In life-cycle models of saving under uncertain lifetime and borrowing constraint, the consumer's wealth must be depleted before the maximum lifetime. This paper investigates the existence, uniqueness, and optimality of the terminal wealth depletion time. It is proved that the optimal terminal wealth depletion time, if such exists, must be unique. If the equation that determines the optimal terminal wealth depletion has multiple solutions, then the location of the optimal solution will depend on the configuration of the solutions. An optimality test is developed to verify whether a candidate solution for the terminal wealth depletion time is indeed optimal. The paper introduces a method new to economics, the Dubovitskii-Milyutin adjoint equation, to analyze the properties of the optimal control problem.     

SUNSPOT EQUILIBRIA IN A PRODUCTION ECONOMY: DO RATIONAL ANIMAL SPIRITS CAUSE OVERPRODUCTION?*

We study a standard two‐period economy with one nominal bond and one firm. The firm finances the input with the nominal bond in the first period and its profits are distributed to the shareholders in the second period. We show that in the neighbourhood of each efficient equilibrium, a sunspot equilibrium also exists. It is shown that the equilibrium interest rate is lower than the efficient level and that there is overproduction in the sunspot equilibrium, under some conditions. However, there is no sunspot equilibrium if the profit share of the firm can be traded as well as the bond.     

WELFARE GAINS AND LOSSES IN SUNSPOT EQUILIBRIA*

We study a standard two period exchange economy with one nominal asset. As is well known, there is a continuum of sunspot equilibria around each efficient equilibrium. A sunspot equilibrium is inefficient but some households may gain in sunspot equilibria relative to the efficient equilibrium. We show that a household's equilibrium utility level is either locally maximized or locally minimized at the efficient equilibrium, and derive a condition which identifies whether or not a household's utility is locally minimized or maximized.     

Asset prices, debt constraints and inefficiency

We consider (possibly non-stationary) economies with endogenous solvency constraints under uncertainty over an infinite horizon, as in Alvarez and Jermann (2000) [5]. A sort of Cass Criterion (Cass, 1972 [10]) completely characterizes constrained inefficiency under the hypothesis of uniform gains from risk-sharing (which is always satisfied in stationary economies when the autarchy is constrained inefficient). Uniform gains from risk-sharing also guarantee a finite value of the intertemporal aggregate endowment at a constrained optimum. Hence, no equilibrium exhibits a null interest rate in the long run. Finally, constrained inefficiency occurs if and only if there exists a feasible redistribution producing a welfare improvement at all contingencies.     

Heterogeneity, returns to scale, and collective action

Abstract .  I analyze the effects of resource inequality and valuation heterogeneity on the provision of public goods with increasing or decreasing returns to scale in production. The existing literature typically takes the agents' characteristics as given and known to the researcher. In contrast, this paper compares collective action provision across groups of agents with resources and valuations for the public good drawn from different known joint distributions. Specifically, I characterize the expected equilibrium public good level as function of various distributional properties and moments. A resource-valuation distribution that first-order stochastically dominates another distribution always results in higher expected public good provision level, independent of the production technology. With decreasing returns to scale in the public good production, higher resource inequality results in higher expected provision. With increasing returns the same result holds when the mean resource level is relatively low, but expected provision decreases in inequality when the mean resource level is high. A parallel result holds for agents' valuations.     

The interaction between monetary and fiscal policies in Turkey: An estimated New Keynesian DSGE model

This paper estimates a New Keynesian open economy DSGE model for Turkey by using Bayesian estimation technique for the period of 2002:q1–2009:q3. It studies fiscal and monetary policy interactions and their role in stabilisation of the economy using a small-scale model following the methodology outlined in Lubik and Schorfheide (2007). The general features of the model can be summarised as follows: Calvo style nominal price rigidities, perfect exchange rate pass-through, complete international asset markets, rule of thumb price setters and distortionary taxation.     

Double dividend,dynamic Laffer effects and public abatement

In a very stylized endogenous growth economy with pollution and public abatement activities and without any production externality, we show that the government may exploit dynamic Laffer effects to achieve a double dividend through an environmental tax reform, while fulfilling its commitment to provide an exogenously specified sequence of expenditures in the form of lump-sum transfers to consumers.     

Bubble-free policy feedback rules

We consider a broad class of linear dynamic stochastic rational-expectations models made of a finite number N of structural equations for N+1 endogenous variables and to be closed by one policy feedback rule. We design, for any model of this class and any stationary VARMA solution of that model, a “bubble-free” policy feedback rule ensuring that this solution is not only the unique stationary solution of the closed model, but also its unique solution. We apply these results to locally linearisable models of the monetary transmission mechanism and obtain interest-rate rules that not only ensure the local determinacy of the targeted equilibrium in the neighbourhood of the steady state considered, but also prevent the economy from gradually leaving this neighbourhood.     

Barro-Gordon revisited: Reputational equilibria with inferential expectations

We incorporate inferential expectations into the Barro-Gordon model (Barro and Gordon, 1983a) of time inconsistency and consider reputational equilibria. The range of sustainable equilibria shrinks as the private sector becomes more belief-conservative.     

The impact of prudence on optimal prevention revisited

We re-examine the link between absolute prudence and self-protection activities. We show that the level of effort chosen by an agent with decreasing absolute prudence is larger than the optimal effort chosen by a risk-neutral agent if the degree of absolute prudence is less than a threshold that is utility-independent and empirically verifiable.     

On the optimality of not allocating

We show that the commitment to not allocate may be exploited by a seller/social planner to increase the expected social surplus that can be achieved in the sale of an indivisible unit.     

Decentralization of Pareto optima in economies with public projects,nonessential private goods and convex costs

Summary In the theory of economies with public goods one usually considers the case in which private goods are essential, i.e., each agent receives a fixed minimum level of utility if he consumes no private goods, irrespective of the public goods consumed. This paper develops the second welfare theorem for economies with public projects and possibly inessential private goods. As a corollary we also derive conditions under which valuation equilibria exist.hank Dolf Talman and an anonymous referee for many useful remarks and annotations of a previous draft of this paper.     

Fundamentals, information, and international capital flows: A welfare analysis

In the recent discussion surrounding the design of a new international financial architecture, enhancing transparency has widely been proposed as a policy essential for increasing the efficiency of international capital markets. This paper uses a simple two-country (two-agent) general equilibrium model with incomplete markets and production to explore the welfare consequences of an increase in public information about country-specific fundamentals (increase in transparency). An improvement in the quality of information has two effects on the ex ante welfare of individual countries: A direct effect that increases the efficiency of global capital allocation and welfare, and an indirect general equilibrium effect that increases asset price volatility and may decrease welfare. When the degree of risk-aversion is low, at least one country will gain from an increase in information quality. If the degree of risk-aversion is high, then there are robust examples of economies for which an increase in information hurts all countries. The paper also discusses how certain institutional arrangements (international derivative markets, international agency) could ensure that all countries gain from better information by providing insurance against information-induced asset price risk.