nep-mic New Economics Papers
on Microeconomics
Issue of 2019‒08‒19
twelve papers chosen by
Jing-Yuan Chiou
National Taipei University

  1. Dynamic Information Design with Diminishing Sensitivity Over News By Jetlir Duraj; Kevin He
  2. On Selecting the Right Agent By Geoffroy de Clippel; Kfir Eliaz; Daniel Fershtman; Kareen Rozen
  3. Boolean Representations of Preferences under Ambiguity By Frick, Mira; Iijima, Ryota; Le Yaouanq, Yves
  4. Costless Information and Costly Verification: A Case for Transparency By Deniz Kattwinkel; Jan Knoepfle
  5. Competing to Persuade a Rationally Inattentive Agent By Vasudha Jain; Mark Whitmeyer
  6. Pure Nash Equilibria and Best-Response Dynamics in Random Games By Ben Amiet; Andrea Collevecchio; Marco Scarsini
  7. A strategic product for belief functions By Ronald Stauber
  8. Patterns of Competitive Interaction By Armstrong, Mark; Vickers, John
  9. Dynamic Vertical Foreclosure By Chiara Fumagalli; Massimo Motta
  10. Ignorance is bliss: a game of regret By Claudia Cerrone; Francesco Feri; Philip R. Neary
  11. Communication with Forgetful Liars By Philippe Jehiel
  12. Multiplayer Bandit Learning, from Competition to Cooperation By Simina Br\^anzei; Yuval Peres

  1. By: Jetlir Duraj; Kevin He
    Abstract: A benevolent sender communicates non-instrumental information over time to a Bayesian receiver who experiences gain-loss utility over changes in beliefs ("news utility"). We show how to inductively compute the optimal dynamic information structure for arbitrary news-utility functions. With diminishing sensitivity over the magnitude of news, contrary to piecewise-linear news-utility models, one-shot resolution of uncertainty is strictly suboptimal under commonly used functional forms. We identify additional conditions that imply the sender optimally releases good news in small pieces but bad news in one clump. By contrast, information structures featuring the opposite skewness - i.e., delivering bad news gradually - are never optimal. A sender lacking commitment power can only credibly convey partial good news when the receiver is sufficiently loss averse. With diminishing sensitivity but no loss aversion, the babbling equilibrium is essentially unique. Contrary to the commitment case, a sender without commitment may generate higher equilibrium news-utility for receivers with higher loss aversion.
    Date: 2019–07
  2. By: Geoffroy de Clippel; Kfir Eliaz; Daniel Fershtman; Kareen Rozen
    Abstract: Each period, a principal must assign one of two agents to some task. Profit is stochastically higher when the agent is qualified for the task. The principal cannot observe qualification. Her only decision is which of the two agents to assign, if any, given the public history of selections and profits. She cannot commit to any rule. While she maximizes expected discounted profits, each agent maximizes his expected discounted selection probabilities. We fully characterize when the principal's first-best payoff is attainable in equilibrium, and identify a simple strategy profile achieving this first-best whenever feasible. We propose a new refinement for dynamic mechanisms (without transfers) where the designer is a player, under which we show the principal's next-best, when the first-best is unachievable, is the one-shot Nash. We show how our analysis extends to variations on the game accommodating more agents, caring about one's own performance, cheap talk and losses.
    Keywords: Dynamic allocation, mechanism design without transfers, mechanism design without commitment
    JEL: D82 D86
    Date: 2019–08
  3. By: Frick, Mira (Yale University); Iijima, Ryota (Yale University); Le Yaouanq, Yves (LMU Munich)
    Abstract: We propose a class of multiple-prior representations of preferences under ambiguity where the belief the decision-maker (DM) uses to evaluate an uncertain prospect is the outcome of a game played by two conflicting forces, Pessimism and Optimism. The model does not restrict the sign of the DM\'s ambiguity attitude, and we show that it provides a unified framework through which to characterize different degrees of ambiguity aversion, as well as to represent context-dependent negative and positive ambiguity attitudes documented in experiments. We prove that our baseline representation, Boolean expected utility (BEU), yields a novel representation of the class of invariant biseparable preferences (Ghirardato, Maccheroni and Marinacci, 2004), which drops uncertainty aversion from maxmin expected utility (Gilboa and Schmeidler, 1989), while extensions of BEU allow for more general departures from independence.
    Keywords: multiple priors; ambiguity; dual-self models;
    JEL: D81
    Date: 2019–07–30
  4. By: Deniz Kattwinkel; Jan Knoepfle
    Abstract: A principal has to take a binary decision. She relies on information privately held by a completely biased agent. The principal cannot incentivize with transfers but can learn the agent's information at a cost. Additionally, the principal privately observes a signal correlated with the agent's type. Transparent mechanisms are optimal: unlike in standard results with correlation, the principal's payoff is the same as if her signal was public. They take a simple cut-off form: favorable signals ensure the agent's preferred action. Signals below this cut-off lead to the nonpreferred action unless the agent appeals. An appeal always triggers type verification.
    Keywords: Mechanism Design without Transfers, Costly Verification, Robust Mechanism Design, Transparency
    JEL: D61 D82 K40
    Date: 2019–07
  5. By: Vasudha Jain; Mark Whitmeyer
    Abstract: Firms strategically disclose product information in order to attract consumers, but recipients often find it costly to process all of it, especially when products have complex features. We study a model of competitive information disclosure by two senders, in which the receiver may garble each sender's experiment, subject to a cost increasing in the informativeness of the garbling. As long as attention costs are not too low, there is an interval of prior means over which it is an equilibrium for both senders to offer full information, which interval expands as attention costs grow. Information on one sender substitutes for information on the other, which allows the receiver to nullify the profitability of a deviation. We thus provide a novel channel through which competition encourages information disclosure.
    Date: 2019–07
  6. By: Ben Amiet; Andrea Collevecchio; Marco Scarsini
    Abstract: Nash equilibria are a central concept in game theory and have applications in fields such as economics, evolutionary biology, theoretical computer science, and many others. Mixed equilibria exist in any finite game, but pure equilibria may fail to exist. We consider the existence of pure Nash equilibria in games where the payoffs are drawn at random. In particular, we consider games where a large number of players can each choose one of two possible actions, and the payoffs are i.i.d. with the possibility of ties. We provide asymptotic results about the random number of pure Nash equilibria, such as fast growth and a central limit theorem. Moreover, we establish a new link between percolation models and game theory to shed light on various aspects of Nash equilibria. Through this connection, we describe in detail the geometry of Nash equilibria and show that, when the probability of ties is small, a best-response dynamics reaches a Nash equilibrium with a probability that quickly approaches one as the number of players grows. We show a multitude of phase transitions depending on a single parameter of the model, that is, the probability of having ties.
    Date: 2019–05
  7. By: Ronald Stauber
    Abstract: The term “belief function” is generally used to refer to a class of capacities that can be viewed as representing ambiguity averse preferences. This paper introduces a definition of equilibrium for normal-form games with ambiguous beliefs, where belief functions are used to describe strategic uncertainty. To capture independence of strategies and beliefs, a novel notion of a “strategic product integral” is introduced for belief functions, based on the Möbius transform of a capacity, and shown to be different from the Choquet integral of an appropriate product capacity. A characterization of the integral in terms of maxmin expected utility expressed relative to elements of the cores of the respective belief functions, is also presented. The resulting equilibrium notion relies on the Möbius transform to embed objectively chosen probabilistic mixed strategies into ambiguous beliefs of opponents about these strategies, while incorporating stronger consistency requirements than those imposed by previous definitions of equilibria under ambiguity. Classification-C72, D81
    Keywords: Belief functions; Product capacities; Equilibrium under ambiguity; Strategic uncertainty
    Date: 2019–04
  8. By: Armstrong, Mark; Vickers, John
    Abstract: We explore patterns of competitive interaction by studying mixed-strategy equilibrium pricing in oligopoly settings where consumers vary in the set of suppliers they consider for their purchase. In the case of "nested reach" we find equilibria, unlike those in existing models, in which price competition is segmented: small firms offer only low prices and large firms only offer high prices. We characterize equilibria in the three-firm case using correlation measures of competition between pairs of firms. We then contrast them with equilibria in the parallel model with capacity constraints. A theme of the analysis is how patterns of consumer consideration matter for competitive outcomes.
    Keywords: Bertrand-Edgeworth competition, price dispersion, consideration sets, mixed strategies, captive customers
    JEL: D43 D83 L11 L13 L15
    Date: 2019–07
  9. By: Chiara Fumagalli; Massimo Motta
    Abstract: This paper shows that vertical foreclosure can have a dynamic rationale. By refusing to supply an efficient downstream rival, a vertically integrated incumbent sacrifices current profits but can exclude the rival by depriving it of the critical profits it needs to be successful. In turn, monopolising the downstream market may prevent the incumbent from losing most of its future profits because: (a) it allows the incumbent to extract more rents from an efficient upstream rival if future upstream entry cannot be discouraged; or (b) it also deters future upstream entry by weakening competition for the input and reducing the post-entry profits of the prospective upstream competitor.
    Keywords: Inefficient foreclosure, Refusal to supply, Scale economies, Exclusion, Monopolisation
    JEL: K21 L41
    Date: 2018
  10. By: Claudia Cerrone (Max Planck Institute for Research on Collective Goods, Bonn); Francesco Feri (Royal Holloway, Department of Economics); Philip R. Neary (Royal Holloway, Department of Economics)
    Abstract: Existing models of regret aversion assume that individuals can make an ex-post comparison between their choice and a foregone alternative. Yet in many situations such a comparison can be made only if someone else chose the alternative option. We develop a model where regret-averse agents must decide between the status quo and a new risky option that outperforms the status quo in expectation, and learn the outcome of the risky option, if unchosen, with a probability that depends on the choices of others. This turns what was previously a series of single-person decision problems into a coordination game. Most notably, regret can facilitate coordination on the status quo { an action that would not be observed if the agents were acting in isolation or had standard preferences. We experimentally test the model and find that regret-averse agents behave as predicted by our theory.
    Keywords: regret aversion, coordination games, information
    JEL: C72 C92 D81 D91
    Date: 2019–07
  11. By: Philippe Jehiel (PJSE - Paris Jourdan Sciences Economiques - UP1 - Université Panthéon-Sorbonne - ENS Paris - École normale supérieure - Paris - INRA - Institut National de la Recherche Agronomique - EHESS - École des hautes études en sciences sociales - ENPC - École des Ponts ParisTech - CNRS - Centre National de la Recherche Scientifique, PSE - Paris School of Economics, UCL - University College of London [London])
    Abstract: I consider multi-round cheap talk communication environments in which, after a lie, the informed party has no memory of the content of the lie. I characterize the equilibria with forgetful liars in such settings assuming that a liar.s expectation about his past lie coincides with the equilibrium distribution of lies aggregated over all possible realizations of the states. The approach is used to shed light on when the full truth is almost surely elicited, when multiple lies can arise in equilibrium, and when inconsistencies trigger harmful consequences.
    Keywords: forgetful liars,lie detection,analogy-based expectations,cheap talk
    Date: 2019–07
  12. By: Simina Br\^anzei; Yuval Peres
    Abstract: The stochastic multi-armed bandit problem is a classic model illustrating the tradeoff between exploration and exploitation. We study the effects of competition and cooperation on this tradeoff. Suppose there are $k$ arms and two players, Alice and Bob. In every round, each player pulls an arm, receives the resulting reward, and observes the choice of the other player but not their reward. Alice's utility is $\Gamma_A + \lambda \Gamma_B$ (and similarly for Bob), where $\Gamma_A$ is Alice's total reward and $\lambda \in [-1,1]$ is a cooperation parameter. At $\lambda = -1$ the players are competing in a zero-sum game, at $\lambda = 1$, they are fully cooperating, and at $\lambda = 0$, they are neutral: each player's utility is their own reward. The model is related to the economics literature on strategic experimentation, where usually the players observe each other's rewards. In the discounted setting, the Gittins index reduces the one-player problem to the comparison between a risky arm, with a prior $\mu$, and a predictable arm with success probability $p$. The value of $p$ where the player is indifferent between the arms is the Gittins index $g(\mu,\beta) > m$, where $m$ is the mean of the risky arm and $\beta$ the discount factor. We show that competing players explore less than a single player: there is $p^* \in (m, g(\mu, \beta))$ so that for all $p > p^*$, the players stay at the predictable arm. However, the players are not completely myopic: they still explore for some $p > m$. On the other hand, cooperating players explore more than a single player. Finally, we show that neutral players learn from each other, receiving strictly higher total rewards than they would playing alone, for all $ p\in (p^*, g(\mu,\beta))$, where $p^*$ is the threshold above which competing players do not explore. We show similar phenomena in the finite horizon setting.
    Date: 2019–08

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