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Peter Wakker animera un séminaire le jeudi 8 décembre à la Maison des sciences économiques, de 14h à 16h, en salle 314 sur: "Delay Sequences for Easy Measurements and Analyses of Hyperbolic Discounting and Dynamic Inconsistency in Intertemporal Choice" il s'agit d'un travail joint avec Arthur Attema, Han Bleichrodt et Kirsten Rohde Résumé: In the same way as expected utility is the classical model for decision under risk, discounted utility, introduced by Samuelson (1937), is the classical model for intertemporal preference. The model is characterized by stationarity of preference. Deviations started receiving interest when, first, empirical studies found systematic violations and, next, mainstream economics incorporated deviating models under the name hyperbolic discounting, popularized by Laibson and others. Under some assumptions, these models lead to violations of dynamic consistency and, hence, to irrational preferences. The simplest model for such deviations is quasi/hyperbolic discounting, capturing only deviations at the initial time point. A sophisticated model, generalized hyperbolic discounting of Prelec & Loewenstein, did not yet receive much attention. We introduce delay sequences for intertemporal preferences. They provide an easy way to empirically measure the extent of deviations from stationarity and, correspondingly, from rationality. They can immediately be measured empirically, needing only paper and pencil. Remarkably, they immediately reveal something as seemingly complex as the graph of the logarithm of the discounting function while needing only paper and pencil, and no computer or calculation device. The first part of this lecture is theoretical, introducing the basic idea of delay sequences and demonstrating how this gives very easy preference foundations for virtually all presently popular models of intertemporal discounting, and measures for quantifying the degree of deviation from stationarity and rationality. The second part is empirical, presenting a measurement of delay sequences of intertemporal decision makers, leading to immediate conclusions about their time attitudes.
Séminaire exceptionnel Professeur invité Centre d'Economie de la Sorbonne Vendredi 2 décembre, 17h00, Maison des Sciences Economiques, 106-112 Bd de l'Hôpital, Paris 13e (métro Campo Formio), Salle 115 : Paulo Klinger Monteiro (EPGE-FGV) Uniform Payoff Security and Nash Equilibrium in Metric Games Abstract: We introduce a condition, uniform payoff security, for games with separable metric strategy spaces and payoffs bounded and measurable in players' strategies. We show that if any such metric game, G, is uniformly payoff secure, then its mixed extension, G', is payoff secure. We also establish that if a uniformly payoff secure metric game G has compact strategy spaces, and if its mixed extension G' has reciprocally upper semicontinuous payoffs, then G has a Nash equilibrium in mixed strategies. We provide several economic examples of metric games satisfying uniform payoff security. JEL Classification: C72