Knowledge that Transforms

Double moral hazard in continuous time generates the familiar warranty pattern with full coverage for an initial block of time. The more complete the warranty, the better the producer's durability incentives and the worse the consumer's maintenance incentives. Using continuous time highlights the need for some warranty bound to avoid reaching the first-best as an unreasonable limit. Early in the paper, an exogenous bound is used, while later the bound arises endogenously from the possibility of abuse and repair. A quadratic example shows that the warranty's duration depends on the relative severity of the two moral hazard problems.

This paper explores the role of complementarities and incomplete markets in economic growth. We analyze the evolution of an economy composed of a countable set of industries. Individual industries exhibit non-convexities in production and are linked by localized technological complementarities. These complementarities, when strong enough, produce multiple equilibria in long-run economic activity. The equilibria have a simple probabilistic structure that demonstrates how local interactions can affect the aggregate equilibrium. The model generates interesting cross-sectional and intertemporal dynamics as coordination problems become the source of aggregate and individual industry volatility. The model also illustrates how the growth of leading sectors can cause a takeoff to a high aggregate production equilibrium.

The costs of hiring a worker generally differ in size from the firing costs. This article investigates optimal labour demand schedules for production and non-production workers of firms that operate under uncertainty and face asymmetric costs of adjusting their workforce. In the empirical part generalised methods of moments (GMM) estimates of the structural parameters of the Euler conditions for production and non-production workers are presented, together with specification and structural stability tests, using time series data of the Netherlands and U.K. manufacturing sectors. We find that asymmetric adjustment costs play an important role in the explanation of unbalanced labour demand between upward and downward movements of the business cycle. Moreover, hiring costs exceed firing costs of production workers, whereas firing costs exceed hiring costs of non-production workers.

We apply the White information matrix (IM) test to the linear regression model with autocorrelated errors. A special case of one component of the test is found to be identical to the Engle Lagrange multiplier (LM) test for autoregressive conditional heteroskedasticity (ARCH). Given Chesher's interpretation of the IM test as a test for parameter heterogeneity, this establishes a connection among the IM test, ARCH and parameter variation. This also enables us to specify conditional heteroskedasticity in a more general and convenient way. Other interesting by-products of our analysis are tests for the variation in conditional and static skewness which we call tests for “heterocliticity”.

The paper examines, within the framework of a multi-dimensional one-step forward-looking model, a special category of rational expectations equilibria. Their support is infinite with two accumulation points (steady states); the stochastic motion of the system is of random-walk type. A general strategy for an existence proof—associated with the study of a dynamical system—stresses necessary conditions. In a simple overlapping-generations model, the proof is made complete—no backwards bending labour supply is required in the pure sunspot case. By continuity, heteroclinic random walk equilibria are also shown to exist when shocks are real.

This paper is an attempt to identify some of the factors that affect the evolution of market structure in a model of dynamic competition between two firms. The stochastic evolution of the state of competition depends on the respective effort rates of the firms. The question is whether the current leader works harder than the laggard—does the ‘gap’ between firms tend to increase or decrease? We show that several effects are at work. The state tends to evolve in the direction where joint payoffs are greater. Since joint payoffs are related to joint product-market profits less joint effort costs, there are two classes of effect: the joint-profit effect and various joint-cost effects. The latter result in part from the pattern of profits, and in part from endpoint effects that give relief from efforts. Asymptotic expansions illuminate these influences. Moreover, we show by numerical simulation that there is another kind of joint-cost effect. The pattern of joint effort costs can influence the pattern of evolution of market structure, and the evolution of the pattern of market structure can influence the pattern of efforts, in a mutually self-reinforcing manner. In particular, there may be equilibria in which this last effect means that the laggard works harder than the leader even though all the other effects work in favour of the leader.

A simple dynamic model of rational learning through market interaction by asymmetrically informed risk-neutral agents, uncertain about a valuation parameter but whose pooled information reveals it, is presented. The model is a variation of the classical partial equilibrium model of learning in rational expectations in which the market price is informative about the unknown parameter only through the actions of agents. It is found that learning from market prices and convergence to the rational expectations equilibrium is slow, at the rate 1/√n1/3 (where n is the number periods of market interaction), whenever the average precision of private information in the market is finite. Convergence obtains at the standard rate 1/√n if there is a positive mass of perfectly informed agents. Comparative static results on more refined measures of the speed of convergence with respect to basic technological and informational parameters are also provided.

This paper characterizes pure-strategy and dominant-strategy Nash equilibrium in non-cooperative games which may have discontinuous and/or non-quasiconcave payoffs. Conditions called diagonal transfer quasiconcavity and uniform transfer quasiconcavity are shown to be necessary and, with conditions called diagonal transfer continuity and transfer upper semicontinuity, sufficient for the existence of pure-strategy and dominant-strategy Nash equilibrium, respectively. The results are used to examine the existence or non-existence of equilibrium in some well-known economic games with discontinuous and/or non-quasiconcave payoffs. For example, we show that the failure of the existence of a pure-strategy Nash equilibrium in the Hotelling model is due to the failure of an aggregator function to be diagonal transfer quasiconcave—not the failure of payoffs to be quasiconcave, as has been elsewhere conjectured.

This paper presents a simple general equilibrium model of optimal taxation in which both private agents and the government can default on their debt. As a benchmark we consider Ramsey equilibria in which the government can precommit to its policies at the beginning of time, but in which private agents can default. We then consider sustainable equilibria in which both government and private agent decision rules are required to be sequentially rational. We completely characterize the set of sustainable equilibria. In particular, we show that when there is sufficiently little discounting and government consumption fluctuates enough, the Ramsey allocations and policies (in which the government never defaults) can be supported by a sustainable equilibrium.

The paper explicitly models price competition in financial markets in which prices are quoted by competing dealers before future demand is observed. The strategic behaviour of informed insiders and uninformed liquidity traders implies that a growing number of market makers leads to a higher risk exposure for the individual market maker which induces higher individual bid-ask-spreads and higher transaction costs for the liquidity traders. Under certain conditions liquidity traders would prefer a monopolistic market maker rather than several competing market makers. The results hold under various assumptions on the strategy space of the market makers.