On the Composition of Committees

This article is concerned with the role of committees in collectivedecision making processes in a world where agents must be motivatedto collect information. Committees improve the quality of decisionmaking by providing information and by coordinating the collectionof information. We address two types of questions. First, howdoes the composition of a committee affect final decisions?Second, what is the optimal composition of a committee fromthe decision maker's point of view? As to the latter question,we show that the cost of information collection plays an importantrole. If this cost is low, then the preferences of the committeemembers should be aligned to those of the decision maker. Memberswith similar preferences as the decision maker collect the properpieces of information. Moreover, manipulation of informationdoes not occur if the preferences of the decision maker andthe members are consonant. If the cost of searching is high,then the committee should be composed of members with polarizedpreferences. Outliers have a strong incentive to search forinformation.     

The value of a stochastic information structure

Upon observing a signal, a Bayesian decision maker updates her probability distribution over the state space, chooses an action, and receives a payoff that depends on the state and the action taken. An information structure determines the set of possible signals and the probability of each signal given a state. For a fixed decision problem, the value of an information structure is the maximal expected utility that the decision maker can get when the observed signals are governed by this structure. Thus, every decision problem induces a preference order over information structures according to their value. We characterize preference orders that can be obtained in this way. We also characterize the functions defined over information structures that measure their value.     

New product launch: herd seeking or herd preventing?

A decision maker offers a new product to a number of potential adopers. He does not know the value of the product, but adopers receive some private information about it. We study how the decision maker may influence learning among adopers by manipulaing the launch sequence when both the decision maker and adopers can learn about the value of the product from previous adoption decisions. The conditions under which the decision maker prefers a sequential launch to a simultaneous launch depend on adopers?? prior beliefs about the value of the product and adoption costs. We derive the decision maker??s optimal launch sequence and study how it endogenizes informational herding.     

PARTISAN ADVOCATES

This paper studies the problem of an uninformed decision maker who acquires expert advice prior to making a decision. I show that it is less costly to hire partisan agents than impartial agents, especially under advocacy, and that the decision maker prefers partisan advocacy to other forms of institutions. I also extend the literature, originating with Dewatripont and Tirole ( 1999 ), to a setting with contracts that condition on information provided and not just the decision made.     

Emotional Temperature,Probabilistic Choice and the Optimal Power of Incentives*

From the time of Plato it has been assumed that emotions cloud rational thinking. Fully rational individuals were supposed to be completely free of emotions. Modern psychological research challenged this paradigm. One of the insights of this research is that though emotions indeed interfere with the ability to evaluate the objective consequences of choices, they also allow the decision maker to feel the difference in utility arising from those choices. In this article, I formalise this intuition by introducing the concept of emotional temperature. I show that there exists a positive optimal emotional temperature, which leads to an irreducible probability of suboptimal choice. I apply the model to characterise the optimal contracts under moral hazard, assuming that the emotional temperature of the decision maker increases when the contract provides more powerful incentives. A more general point the article makes is that a mechanism designer needs to be aware that the mechanism will not only affect incentives but also the degree of rationality of the agents.     

Minimax regret with imperfect ex-post knowledge of the state

We consider decision problems under complete ignorance and extend the minimax regret principle to situations where, after taking an action, the decision maker does not necessarily learn the state of the world. For example, if the decision maker only learns what the outcome is, then all she knows is that the actual state is one of the (possibly several) states that yield the observed outcome under the chosen action. We refer to this situation as imperfect ex-post information. We show that, given a choice between more information and less information, the decision maker prefers the latter. We also extend the framework to encompass the possibility of less than the extreme degree of pessimism that characterizes the minimax regret criterion.     

Implementation with partial provability

We extend implementation theory by allowing the social choice function to depend on more than just the preferences of the agents and allowing agents to support their statements with hard evidence. We show that a simple condition on evidence is necessary for the implementation of a social choice function f when the preferences of the agents are state independent and sufficient for implementation for any preferences (including state dependent) with at least three agents if the social planner can perform small monetary transfers beyond those called for by f. If transfers can be large, f can be implemented in a game with perfect information when there are at least two players under a boundedness assumption. For both results, transfers only occur out of equilibrium. The use of evidence enables implementation which is robust in the sense that the planner needs little information about agents? preferences or beliefs and agents need little information about each others? preferences. Our results are robust to evidence forgery at any strictly positive cost.     

The art of conversation: eliciting information from experts through multi-stage communication

We examine the strategic interaction between an informed expert and an uninformed decision maker, extending the analysis of Crawford and Sobel (Econometrica 50 (1982) 1431). We modify their model to allow for more extensive communication between the two parties and show that face-to-face communication between the expert and the uninformed decision maker followed by a written report from the expert leads to improved information transmission. In (almost) all cases, there exists an equilibrium in our modified model that ex ante Pareto dominates all of the equilibria identified by Crawford and Sobel. This remains true even if the expert's bias is so great that in their model no information would be disclosed.     

Anti-herding and strategic consultation

In this paper I analyze how careerist decision makers aggregate and use information provided by others. I find that decision makers who are motivated by reputation concerns tend to ‘anti-herding’, i.e., they excessively contradict public information such as the prior or others’ recommendations. I also find that some decision makers may deliberately act unilaterally and not consult advisers although advice is costless. Moreover, advisers to the decision maker may not report their information truthfully. Even if the advisers care only about the outcome, they bias their recommendation since they anticipate inefficient anti-herding behavior by the decision maker.     

Stock Analysts: Experts on Whose Behalf?

Investors rely on the opinions of experts to help us pick stocks. Whether one buys stocks through a 401(k) plan, or manage the mutual fund for individuals investing in the 401(k) the decision maker utilizes expert opinion. Those experts are supposed to be stock analysts. Recent scandals like Enron have caused these analysts to be much maligned. We will examine the role of those analysts, their motivations and the amount of useful information they provide.     

Optimal voting schemes with costly information acquisition

A group of individuals with identical preferences must make a decision under uncertainty about which decision is best. Before the decision is made, each agent can privately acquire a costly and imperfect signal. We discuss how to design a mechanism for eliciting and aggregating the collected information so as to maximize ex-ante social welfare.We first show that, of all mechanisms, a sequential one is optimal and works as follows. At random, one agent at a time is selected to acquire information and report the resulting signal. Agents are informed of neither their position in the sequence nor of other reports. Acquiring information when called upon and reporting truthfully is an equilibrium.We next characterize the ex-ante optimal scheme among all ex-post efficient mechanisms. In this mechanism, a decision is made when the precision of the posterior exceeds a cut-off that decreases with each additional report. The restriction to ex-post efficiency is shown to be without loss when the available signals are sufficiently imprecise. On the other hand, ex-post efficient mechanisms are shown to be suboptimal when the cost of information acquisition is sufficiently small.     

A Bayesian Approach to Uncertainty Aversion

The Ellsberg paradox demonstrates that people's beliefs over uncertain events might not be representable by subjective probability. We show that if a risk averse decision maker, who has a well defined Bayesian prior, perceives an Ellsberg type decision problem as possibly composed of a bundle of several positively correlated problems, she will be uncertainty averse. We generalize this argument and derive sufficient conditions for uncertainty aversion.     

Sequential decisions with tests

We consider a principal-agent problem where the principal wishes to be endorsed by a sequence of agents, but cannot truthfully reveal type. In the standard “herding” model, the agents learn from each other's decisions, which can lead to cascades on a given decision when later agents' private information is swamped. We augment the standard model to allow the principal to subject herself to a test designed to provide public information about her type. She must decide how tough a test to attempt from a continuum of test types, which involves trading off the higher probability of passing an easier test against the greater impact from passing a tougher test. We find that the principal will always choose to be tested, and will prefer a tough test to a neutral or easy one.     

Compensations in Information Collecting Situations: A Cooperative Approach

This paper addresses the question of how to compensate people who provide relevant information to a decision maker who faces uncertainty. Several compensation rules for the decision maker are suggested and these are studied in a cooperative environment.     

Thinking Ahead: The Decision Problem

We propose a model of costly decision making based on time-costs of deliberating current and future decisions. We model an individual decision-maker's thinking process as a thought-experiment that takes time, and lets the decision maker 'think ahead' about future decision problems in yet unrealized states of nature. By formulating an intertemporal, state-contingent, planning problem which may involve costly deliberation in every state of nature, and by letting the decision maker deliberate ahead of the realization of a state, we attempt to capture the basic observation that individuals generally do not think through a complete action plan. Instead, individuals prioritize their thinking and leave deliberations on less important decisions to the time or event when they arise.     

Pigouvian pricing and stochastic evolutionary implementation

We study the implementation of efficient behavior in settings with externalities. A planner would like to ensure that a group of agents make socially optimal choices, but he only has limited information about the agents’ preferences, and can only distinguish individual agents through the actions they choose. We describe the agents’ behavior using a stochastic evolutionary model, assuming that their choice probabilities are given by the logit choice rule. We prove that there is a simple price scheme with the following property: regardless of the realization of preferences, a group of agents subjected to the price scheme will spend the vast majority of time in the long run behaving efficiently. The price scheme defines a game that may possess multiple equilibria, but we are able to obtain a unique and efficient selection from this set because of the stochastic nature of the agents’ choice rule. We conclude by comparing the performance of our price scheme with that of VCG mechanisms.     

Merger negotiations and ex-post regret

We consider a setting in which two potential merger partners each possess private information pertaining both to the profitability of the merged entity and to stand-alone profits, and we investigate the extent to which this private information makes ex-post regret an unavoidable phenomenon in merger negotiations. To this end, we consider ex-post incentive compatible mechanisms, which use both players' reports to determine whether or not a merger will take place and what each player will earn in each case. When the outside option of at least one player is known, the efficient merger decision can be implemented by such a mechanism under plausible budget-balance requirements. When neither outside option is known, we show that the potential for regret-free implementation is much more limited, unless the budget balance condition is relaxed to permit money-burning in the case of false reports.     

Persuasion,binary choice,and the costs of dishonesty

We study the strategic interaction between a decision maker who needs to take a binary decision but is uncertain about relevant facts and an informed expert who can send a message to the decision maker but has a preference over the decision. We show that the probability that the expert can persuade the decision maker to take the expert’s preferred decision is a hump-shaped function of his costs of sending dishonest messages.     

Approximate tâtonnement processes

Summary We introduce a probabilistic model for price adjustment in an exchange economy which approximates the classical Walras tâtonnement process while avoiding many of its unrealistic features. The model is decentralized in that the trades permitted to an agent and the resulting price changes depend only on the commodity vector currently held by that agent, and not on the commodity vectors held by the other agents in the economy. Our results will show that the Walras tâtonnement process can be decentralized without changing its behavior on the macroeconomic scale. Our model has a finite set of commodities, a market maker who adjusts prices, and a large finite set of agents who trade only with the market maker. Each agent has a demand function depending on his commodity vector and the price vector. At each discrete time, one agent is chosen at random and exchanges his current commodity vector for his demand vector. Then the market maker adjusts the price vector by an amount which depends on the selected agent's commodity vector and the current price. Prices are adjusted rapidly enough to avoid prolonged trading at the wrong price, but slowly enough so that a substantial price change will depend on a significant simple of agents. The main result shows that with probability arbitrarily close to one the price will rapidly approach and then remain close to an equilibrium value, following a path which is close to the price path of the corresponding tâtonnement process.     

The role of externalities and information aggregation in market collapse

We examine the role that belief, network externality, and information aggregation play in inefficient market collapses. After receiving consecutive negative shocks, some ex-ante identical Bayesian agents will be discouraged about the unknown state of the market they invest; therefore, they will stop investing. This decision will have two effects: first, it will cause agents to aggregate information through social/observational learning; second, it will decrease the network externality effect. We show that there might be an inefficient market collapse if the externality effect diminishes too much, and the cost of re-entry to the market is too high. We also analyze the effects of strategic delay and experimentation on the exit decision of the agents. I especially thank Thomas D. Jeitschko, Matthew Mitchell, B. Ravikumar Ted Temzelides. I also thank anonymous referees, an associate editor, John Conlon, Larry Samuelson, Troy Tassier, Stephen Williamson, and seminar participants of the University of Saskatchewan, Georgia Tech, Concordia University, University of Manitoba, Iowa Alumni Workshop, Midwest Economic Theory Conferences held at Indiana Bloomington, and Notre Dame, and 1st International Conference on Business, Management and Economics organized by Yasar University.