Economics: Research Guide

We develop a leverage theory of tying in markets with network effects. When a monopolist in one market cannot perfectly extract surplus from consumers, tying can be a mechanism through which unexploited consumer surplus is used as a demand-side leverage to create a “quasi-installed base” advantage in another market characterized by network effects. Our mechanism does not require any precommitment to tying; rather, tying emerges as a best response that lowers the quality of tied-market rivals. While tying can lead to exclusion of tied-market rivals, it can also expand use of the tying product, leading to ambiguous welfare effects.

We focus on the basic one-to-one two-sided matching model, where there are two disjoint sets of agents of equal size, and each agent in a set has preferences on the agents in the other set, modelled by linear orders. The goal is to find a matching that associates each agent in one set with one and only one agent in the other set based on the agents' preferences. A mechanism is a rule that associates a set of matchings to each preference profile. Stability, which refers to the capability to select only stable matchings, is an important property a mechanism should fulfill. Another crucial property, especially useful for applications, is resoluteness, which requires that the mechanism always se..

This note elaborates on Luce and Narens' (1978) axiomatic derivation of subjective probability, which generically satisfies the multiplicative law by removing requirement for the derived subjective probability to be non-atomic. For the two original sample spaces, we add the sample space defined by the direct product of the original sample spaces and the sample space of the auxiliary experiment. As a main result, the necessary and sufficient conditions are provided for the likelihood relation on the events of the sample spaces to be represented by the subjective probability satisfying the law with respect to the direct product, allowing atoms in the original sample spaces.

In his seminal work on the political economy of dictatorship, Ronald Wintrobe (1998) posited the existence of a "dictator's dilemma, " in which repression leaves an autocrat less secure by reducing information about discontent. We explore the nature and resolution of this dilemma with a formalization that builds on recent work in the political economy of nondemocracy. When the regime is sufficiently repressive, and the dictator's popularity correspondingly unclear to opposition as well as autocrat, the ruler faces two unattractive options: he can mobilize the repressive apparatus, even though there may be no threat to his rule, or he can refrain from mobilizing, even though the threat may be..

We examine an economy in which interactions are more productive if agents can trust others to refrain from cheating. Some agents are scoundrels, who always cheat, while others cheat only if the cost of cheating, a decreasing function of the proportion of cheaters, is sufficiently low. The economy exhibits multiple equilibria. As the proportion of scoundrels in the economy declines, the high-trust equilibrium can be disrupted by arbitrarily small perturbations or infusions of low-trust agents, while the low-trust equilibrium becomes impervious to perturbations and infusions of high-trust agents. The resilience of trust may thus hinge upon the prevalence of scoundrels.

A primitive assumption underlying Aumann (1974, 1987) is that all players of a game may correlate their strategies by agreeing on a common single ’public roulette’. A natural extension of this idea is the study of strategies when the assumption of a single randomdevice common to all the players (public roulette) is dropped and (arbitrary) disjoint subsets of players forming a coalition structure are allowed to use independent randomdevices (private roulette) a la Aumann. Undermultiple independent randomdevices, the coalitionsmixed strategies forman equilibrium of the induced non-cooperative game played across the coalitions–the ’partitioned game’–when the profile of such coalitio..

We introduce loss aversion into a model of conspicuous consumption in networks. Agents allocate heterogeneous incomes between a conventional good and a status good. They interact over a connected network and compare their status consumption to their neighbors’ average consumption. We find that aversion to lying below the social reference point has a profound impact. If loss aversion is large relative to income heterogeneity, a continuum of conformist Nash equilibria emerges. Agents have the same status consumption, despite differences in incomes and network positions, and the equilibrium is indeterminate. Otherwise, there is a unique Nash equilibrium and status consumption depends on ..

Majority voting is considered an efficient information aggregation mechanism in committee decision-making. We examine if this holds in environments where voters first need to acquire information from sources of varied quality and cost. In such environments, efficiency may depend on free-riding incentives and the ‘transparency’ regime - the knowledge voters have about other voters’ acquired information. Intuitively, more transparent regimes should improve efficiency. Our theoretical model instead demonstrates that under some conditions, less transparent regimes can match the rate of efficient information aggregation in more transparent regimes if all members cast a vote based on the inf..

In competitive settings, disparities in player strength are common. It is intuitively unclear whether a stronger player would opt for larger or smaller effort compared to weaker players. Larger effort could leverage their strength, while lower effort might be justified by their higher probability of winning regardless of effort. We analyze contests with three or more players, exploring when stronger players exert larger or lower effort. To rank efforts, it suffices to compare marginal utilities in situations where efforts are equal. Effort ranking depends on differences in hazard rates (which are smaller for stronger players) and reversed hazard rates (which are larger for stronger players)...

Consider an economy with equal amounts of N types of goods, to be allocated to agents with strict quasi-convex preferences over lotteries. We show that ex-ante, all feasible and Pareto efficient al- locations give almost all agents a binary lottery. Therefore, even if all preferences are the same, some identical agents necessarily receive different lotteries. Our results imply that many of the popular alloca- tion mechanisms used in practice are not ex-ante efficient. Assuming the reduction of compound lotteries axiom, social welfare deteriorates by first randomizing over these binary lotteries. Full ex-ante equality can be achieved if agents satisfy the compound independence axiom.

We consider a decision maker who is unaware of objects to be sampled and thus cannot form beliefs about the occurrence of particular objects. Ex ante she can form beliefs about the occurrence of novelty and the frequencies of yet to be known objects. Conditional on any sampled objects, she can also form beliefs about the next object being novel or being one of the previously sampled objects. We characterize behaviorally such beliefs under subjective expected utility. In doing so, we relate "reverse" Bayesianism, a central property in the literature on decision making under growing awareness, with exchangeable random partitions, the central property in the literature on the discovery of speci..

This paper considers a binary decision to be made by a committee- canonically, a jury- through a voting procedure. Each juror must vote on whether a defendant is guilty or not guilty. The voting rule aggregates the votes to determine whether the defendant is convicted or acquitted. We focus on the unanimity rule (convict if and only if all vote guilty), and we consider jurors who share ambiguous prior beliefs as in Ellis (2016). Our contribution is twofold. First, we identify all symmetric equilibria of these voting games. Second, we show that ambiguity may drastically undermine McLennan's (1998) results on decision quality: unlike in the absence of ambiguity, the ex ante optimal symmetric s..

In a coordination game with multiple Pareto ordered equilibria and population uncertainty, we show that group size helps select a unique equilibrium, for reasons reminiscent of the global games literature. A critical mass phenomenon emerges at equilibrium. Group size has an emboldening effect on participants.

This paper studies bargaining between a seller and a buyer with binary private valuation. Because the setting is more tractable than the case of general valuation distributions (studied in Gul et al., 1986), we are able to explicitly construct the full set of equilibria via induction. This lets us provide a simple proof of the Coase conjecture and obtain new results: The seller extracts all surplus as she becomes more patient, and the equilibrium outcome converges to the perfect-information outcome as private information vanishes. We also fully characterize the case where there is a deadline: We establish that if the probability that the buyer’s valuation is high is large enough, then the ..

We present a model of delegation with moral hazard. A principal delegates a decision to an agent, who affects the distribution of the state of the world by exerting costly and unobservable effort. The principal faces a trade-off between (i) granting the agent discretion, so he can adapt the decision to the state and (ii) limiting the agent’s discretion, to induce him to exert effort. Our model is flexible on how effort affects the state distribution, thus capturing several distinct economic environments. Optimal delegation takes one of four simple forms, all commonly used in practice: floors, ceilings, floor-ceilings or gaps.

I study a dynamic model of durable-good monopoly where the seller cannot commit to future prices and is uncertain about the buyer’s value. I adopt a prior-free approach where the seller minimises lifetime regret against the worstcase type of the buyer. In the unique equilibrium the seller’s worst-case regret against types who purchase at any given time equals the worst-case regret against types who purchase at any other time. The seller cannot profitably deviate even if he could commit to his deviation. Despite this, the equilibrium does not match the commitment outcome. This is because the seller’s objective is endogenously determined by his optimal counterfactual behaviour against ea..

We consider a decision maker who is unaware of objects to be sampled and thus cannot form beliefs about the occurrence of particular objects. Ex ante she can form beliefs about the occurrence of novelty and the frequencies of yet to be known objects. Conditional on any sampled objects, she can also form beliefs about the next object being novel or being one of the previously sampled objects. We characterize behaviorally such beliefs under subjective expected utility. In doing so, we relate "reverse" Bayesianism, a central property in the literature on decision making under growing awareness, with exchangeable random partitions, the central property in the literature on the discovery of speci..

Colonel Blotto games with discrete strategy spaces effectively illustrate the intricate nature of multidimensional strategic reasoning. This paper studies the equilibrium set of such games where, in line with prior experimental work, the tie-breaking rule is allowed to be flexible. We begin by pointing out that equilibrium constructions known from the literature extend to our class of games. However, we also note that, irrespective of the tie-breaking rule, the equilibrium set is excessively large. Specifically, any pure strategy that allocates at most twice the fair share to each battlefield is used with positive probability in some equilibrium. Furthermore, refinements based on the elimina..

We analyze dynamic capital allocation and risk sharing between a principal and many agents, who privately observe their output. The state variables of the mechanism design problem are aggregate capital and the distribution of continuation utilities across agents. This gives rise to a Bellman equation in an infinite dimensional space, which we solve with mean-field techniques. We fully characterize the optimal mechanism and show that the level of risk agents must be exposed to for incentive reasons is decreasing in their initial outside utility. We extend classical welfare theorems by showing that any incentive-constrained optimal allocation can be implemented as an equilibrium allocation, wi..

Auction models are convenient abstractions of informal price-formation processes that arise in markets for assets or services. These processes involve frictions such as bidder recruitment costs for sellers, participation costs for bidders, and limitations on sellers' commitment abilities. This paper develops an auction model that captures such frictions. We derive several novel predictions; in particular, we find that outcomes are often inefficient, and the market sometimes unravels.

We study information transmission through informal elections. Our leading example is that of protests in which there may be positive costs or benefits of participation. The aggregate turnout provides information to a policy maker. However, the presence of activists adds noise to the turnout. The interplay between noise and participation costs leads to strategic substitution and complementarity effects in citizens’ participation choices, and we characterize the implications for the informativeness of protests. In particular, we show that rather than being a friction, costs may facilitate information transmission by lending credibility to protest participation.

We study how workers' concern for coworkers' ability (CfCA) affects competition in the labor market. Two firms offer nonlinear contracts to a unit mass of prospective workers. Firms may differ in their marginal productivity, while workers are heterogeneous in their ability (high or low) and their taste for being employed by any of the two firms. Workers receive a utility premium when employed by the firm hiring most high-ability workers and suffer a utility loss if hired by its competitor. These premiums/losses are endogenously determined. We characterize contracts and workers' sorting into the two firms under complete and private information on workers' ability. We show that CfCA is detrime..

In competitive settings, disparities in player strength are common. It is intuitively unclear whether a stronger player would opt for larger or smaller effort compared to weaker players. Larger effort could leverage their strength, while lower effort might be justified by their higher probability of winning regardless of effort. We analyze contests with three or more players, exploring when stronger players exert larger or lower effort. To rank efforts, it suffices to compare marginal utilities in situations where efforts are equal. Effort ranking depends on differences in hazard rates (which are smaller for stronger players) and reversed hazard rates (which are larger for stronger players)...

We study how interest alignment between CEOs and corporate boards influences investment efficiency and identify a novel force behind the benefit of misaligned preferences. Our model entails a CEO who encounters a project, gathers investment-relevant information, and decides whether or not to present the project implementation for approval by a sequentially rational board of directors. The CEO may be able to strategically choose the properties of the collected information---this happens, for instance, if the project is ``novel" in the sense that it explores new technology, business concept, or market and directors are less knowledgeable about it. We find that only sufficiently conservative an..

Product design is studied in a simple duopoly where firms compete à la Cournot, goods are hedonically differentiated and consumers have preferences defined over characteristics. What we find is that, in equilibrium, firms choose the same product’s design. This results in horizontal product differentiation being minimal.

As firms' pricing strategies increasingly rely on algorithms, two concerns have received much attention: algorithmic tacit collusion and price discrimination. This paper investigates the interaction between these two issues through simulations. In each period, a new buyer arrives with independently and identically distributed willingness to pay (WTP), and each firm, observing private signals about WTP, adopts Q-learning algorithms to set prices. We document two novel mechanisms that lead to collusive outcomes. Under asymmetric information, the algorithm with information advantage adopts a Bait-and-Restrained-Exploit strategy, surrendering profits on some signals by setting higher prices, whi..

We study how pricing affects the division of surplus among buyers in auctions for multiple units. Our equity objective may be important, e.g., for competition concerns in downstream markets, complementing the long-standing debate on revenue and efficiency. We study a canonical model of auctions for multiple indivisible units with unit demand buyers and valuations with a private and a common component and consider all pricing rules that are a mixture (i.e., a convex combination) of pay-as-bid and uniform pricing. We propose the winners' empirical variance (WEV), the expected empirical variance of surplus among the winners, as a metric for surplus equity. We show that, for a range of private-c..

This paper investigates a class of socialwelfare orderings that satisfy the standard and acceptable axioms in the literature: anonymity, strong Pareto, separability, and Pigou-Dalton transfer (or, convexity). Due to the lack of continuity, we show that the class of social welfare orderings typically has some thresholds satisfying the following property, which we call level-oligarchy: individuals whose utility is less than the value are prioritized over the other individuals whose utility is greater than the value. First, we provide the novel reduced form characterization that a social welfare ordering satisfies anonymity, strong Pareto, separability, and convexity must be either the weak gen..

We provide the first axiomatic treatment of two of the most fundamental far-sighted solution concepts. We then extend our analysis to include an axiomatization of the stable set to the extent that it is farsighted. In fi nite abstract games a solution is the largest consistent set if and only if it is maximally supportable and nonempty. In any abstract game a solution is the farsighted stable set if and only if it is minimally supportable, consistent, conversely consistent and nonempty in finite horizon games. We call the stable set that does not suffer from Harsanyi (1974)'s critique of myopia the Harsanyi stable set. In any abstract game a solution is the Harsanyi stable set if and only if..

Miscalibrated beliefs generally compromise the quality of workers' decisions. Why might a firm prefer to hire an individual known to be overconfident? In this paper, I explore the role of such biases when members of the organization disagree about the right course of action. I present a model in which an agent uses his private information to make a choice on behalf of a principal. In this setting, I consider what I call the belief design problem: how would the principal like the agent to interpret his observations? I provide conditions under which the solution indicates a preference for a well-calibrated, an underconfident, or an overconfident agent. A well-calibrated agent is preferred if a..