Knowledge that Transforms

Available from Centro de Informacion y Documentacion Cientifica CINDOC. Joaquin Costa, 22. 28002 Madrid. SPAIN / CINDOC - Centro de Informaciòn y Documentaciòn Cientìfica

A definition of extended memory is provided, generalizing the ideas of long memory and persistence, based on the properties of forecasts over long horizons. Specification of nonlinear models with variables having extended memory is considered in terms of the balance of an equation and it is suggested that many more types of misspecification can occur than with usual situations and could produce important specification errors. Tests of linearity and standard methods of nonlinear modeling are briefly considered and advice is given on circumstances in which they can be used. Copyright 1995 by The Econometric Society.

We examine the second order properties of various quantities of interest in the partially linear regression model. We obtain a stochastic expansion with remainder op(n -2/4), where ,u < 1/2, for the standardized semiparametric least squares estimator, a standard error estimator, and a studentized statistic. We use the second order expansions to correct the standard error estimates for second order effects, and to define a method of bandwidth choice. A Monte Carlo experiment provides favorable evidence on our method of bandwidth choice.

This paper proposes a model of the process by which players learn to play repeated coordination games, with the goal of understanding the results of some recent experiments.In those experiments the dynamics of subjects' strategy choices and the resulting patterns of discrimination among equilibria varied systematically with the rule for determining payoffs and the size of the interacting groups, in ways that are not adequately explained by available methods of analysis.The model suggests a possible explanation by showing how the dispersion of subjects' beliefs interacts with the learning process to determine the probability distribution of its dynamics and limiting outcome.

The authors present three distinct approaches to perfect and proper equilibria for infinite normal form games. In the first two approaches, players 'tremble' in the infinite game playing full support approximate best responses to others' strategies. In the strong approach, a tremble assigns high probability to the set of pure best responses; in the weak approach, it assigns high probability to a neighborhood of this set. The third, limit-of-finite approach applies traditional refinements to sequences of successively larger finite games. Overall, the strong approach to equilibrium refinement most fully respects the structure of infinite games. Copyright 1995 by The Econometric Society.

We analyze optimal mechanisms in environments where sellers are privately informed about quality. A methodology is provided for deriving conditions that are necessary and sufficient to determine when two simple trading environments maximize either social or private surplus. The commonly used auction mechanism is frequently inefficient in procurement environments. Often, the optimal mechanism is simply to order potential suppliers and to tender take-it-or-leave-it offers to each sequentially. We completely characterize the environments in which either mechanism is optimal. In doing so, we develop a general methodology that determines when and if a given trading institution is optimal.

A new asymptotic theory of regression is introduced for possibly nonstationary time series. The regressors are assumed to be generated by a linear process with martingale difference innovations. The conditional variances of these martingale differences are specified as autoregressive stochastic volatility processes with autoregressive roots that are local to unity. The author finds conditions under which the least squares estimates are consistent and asymptotically normal. A simple adaptive estimator is proposed which achieves the same asymptotic distribution as the generalized least squares estimator without requiring parameter assumptions for the stochastic volatility process. Copyright 1995 by The Econometric Society.

Rubinstein's alternating-offers bargaining model is enriched by assuming that players' payoffs in disagreement periods are determined by a normal form game. It is shown that such a model can have multiple perfect equilibria, including inefficient ones, provided that players are sufficiently patient. Delay is possible even though there is perfect information and the players are fully rational. The length of delay depends only on the payoff structure of the disagreement game and not on the discount factor. Not all feasible and individually rational payoffs of the disagreement game can be supported as average disagreement payoffs. Indeed, some negotiation games have a unique perfect equilibrium with immediate agreement.

[This study demonstrates the possibility of ergodically chaotic optimal accumulation in the case in which future utilities are discounted arbitrarily weakly. For this purpose, we use a two-sector model with Leontief production functions and construct a condition under which the optimal transition function is unimodal and expansive. We demonstrate that the set of parameter values satisfying that condition is nonempty no matter how weakly the future utilities are discounted.]