Calendrier du 20 novembre 2017
Roy Seminar (ADRES)
Du 20/11/2017 de 17:00 à 18:30
Salle R1-09, Campus Jourdan, 48 boulevard Jourdan, 75014 Paris
ESPONDA Ignacio (UC Santa Barbara )
Equilibrium in Bayesian Markov Decision Processes
écrit avec Demian Pouzo
Abstract:
We provide an equilibrium framework for modeling the behavior of an agent who holds a simplified view of a dynamic optimization problem. The agent faces a Markov Decision Process, where a transition probability function determines the evolution of a state variable as a function of the previous state and the agent's action. The agent is uncertain about the true transition function and has a prior over a set of possible transition functions; this set reflects the agent's (possibly simplified) view of her environment and may not contain the true function. We define an equilibrium concept and provide conditions under which it characterizes steady-state behavior when the agent updates her beliefs using Bayes' rule. Unlike the case for static environments, however, an equilibrium approach for the dynamic setting cannot be used to characterize those steady states where the agent perceives that learning is incomplete. Two key features of our approach is that it distinguishes between the agent's simplified model and the true primitives and that the agent's belief is determined endogenously in equilibrium.
Régulation et Environnement
Du 20/11/2017 de 12:00 à 13:30
Salle R2-01, Campus Jourdan, 48 boulevard Jourdan, 75014 Paris
DUSO Tomaso (DIW (Berlin) )
The Effect of Retail Mergers on Prices and Variety: An Ex-post Evaluation
écrit avec Elena Argentesi, Paolo Buccirossi, Roberto Cervone, Alessia Marrazzo
Astract
We use an original dataset on Dutch supermarkets to assess the effect of a merger that was conditionally approved by the Dutch Competition Authority (ACM) on prices and on the depth of assortment. We adopt a difference-in-differences strategy that exploits local variation in the merger's effects and we further control for selection on observables when defining our control group. We find that the merger did not affect individual products' prices but it led the merging parties to reposition their assortment and increase average category prices. While the low-quality target stores reduced the depth of their assortment when in direct competition with the acquirer's stores, the latter increased their product variety. By analyzing the effect of the merger on category prices, we find that the target most likely dropped high price products, while the acquirer added more of them. These findings suggests that the merging firms reposition their product offerings in order to avoid cannibalization and lessen local competition. We further show that other dimensions of heterogeneity such as market concentration, whether a divestiture was imposed, and the re-branding strategy of the target stores are important to explain the post-merger dynamics. A simple theoretical model of local-market assortment competition explains most of our findings.
Paris Game Theory Seminar
Du 20/11/2017 de 11:00 à 12:00
salle 01 (rez-de-chaussée) au Centre Emile Borel de l'Institut Henri Poincaré, 11 rue Pierre et Marie Curie, Paris 5ème
CORREA José (Universidad de Chile)
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