Knowledge that Transforms

We study a general implementation problem for exchange economies with a continuum of players and private information, and test the robustness of the results for sequences of approximating finite economies. Assuming that the designer knows the distribution of the characteristics in the economy we consider continuous and unique implementation in both its equilibrium and dominant strategies versions and obtain results for general self-selective (first- and second-best) allocations. An upper hemicontinuity property of Bayesian equilibria of approximating economies for continuous mechanisms is demonstrated. Using this, we can, for example, conclude that if a given continuous mechanism implements uniquely a Walrasian allocation in the continuum economy then all Bayesian equilibria of large approximation economies will (with probability close to one) yield an allocation which is almost ex-post Pareto optimal.

This paper presents a dynamic asset-pricing model under asymmetric information. Investors have different information concerning the future growth rate of dividends. They rationally extract information from prices as well as dividends and maximize their expected utility. The model has a closed-form solution to the rational expectations equilibrium. We find that existence of uninformed investors increases the risk premium. Supply shocks can affect the risk premium only under asymmetric information. Information asymmetry among investors can increase price volatility and negative autocorrelation in returns. Less-informed investors may rztionally behave like price chasers.

This paper studies the stability of competitive equilibria in a model of aggregate employment when the representative agent uses a least-squares forecasting procedure. It is shown that the Pareto inferior low employment steady state is always unstable under least-squares learning, even if it is stable under perfect foresight. The high employment steady state is stable under learning if and only if it is saddle point stable under perfect foresight. This weakens multiple equilibrium theories of coordination failure that purport to explain persistently high unemployment. The Pareto superior high employment steady state will be the focal point of individual forecasting.

This paper examines the reflection problem that arises when a researcher observing the distribution of behaviour in a population tries to infer whether the average behaviour in some group influences the behaviour of the individuals that comprise the group. It is found that inference is not possible unless the researcher has prior information specifying the compisition of reference groups. If this information is available, the prospects for inference depend critically on the population relationship between the variables defining reference groups and those directly affecting outcomes. Inference is difficult to implossible if these variables are functionally dependent or are statistically independent. The prospects are better if the variables defining reference groups and those directly affecting outcomes are moderately related in the population.

This paper analyses life-cycle consumption plans and distinguishes between temporal risk aversion and intertemporal substitution. The results assume that felicity functions are quadratic and that income follows a linear model with normally distributed errors. Stochastic dynamic programming then yields closed-loop linear decision rules. Certainty equivalence no longer holds, but instead households play a min-max strategy against nature. One finds a rationale for precautionary saving and a larger sensitivity of changes in consumption to income innovations.

A time-varying stochastic devaluation risk is introduced in a model of exchange rate target zones. The model produces realistic patterns of covariation between exchange rates and interest rate differentials, which previous target zone models have been unable to do. A “drift adjustment” method to estimate devaluation expectations from data is suggested.

We investigate the consequences of imposing additivity on community preferences. We show that there are important implications of additive community preferences that are not implied by the additivity of a single consumer's preferences. In particular, we show that imposing additivity on community preferences implies the existence of a representative consumer with a utility function in the CES family. We demonstrate the restrictive nature of these implications with three examples. Our interpretation of the results is that single consumer models are unable to adequately represent important features of multi-consumer economies.

This paper shows in two ways that the degree to which free-riding diminishes the performance of deterministic partnerships may be less than has been generally thought. First, a necessary and sufficient condition is provided for a partnership to sustain full efficiency. It implies that many non-trivial partnerships sustain efficiency, such as generic ones with finite action spaces, and neoclassical ones with Leontief technologies. Second, approximate efficiency is shown to be achievable in a large class of partnerships, including ones with smooth and monotonic production and disutility functions. Approximate efficiency is achieved by mixed-strategy equilibria: one partner takes, with small probability, an inefficient action. The degree to which efficiency is approximated is restricted only by the amount of liability the partners can bear. Nonetheless, their equilibrium payments are not arbitrarily large.