Remain silent and ye shall suffer: seller exploitation of reticent buyers in an experimental reputation system

By providing incentives for sellers to act in a trustworthy manner, reputation mechanisms can mitigate moral-hazard problems when particular buyers and sellers interact infrequently. However, these mechanisms rely on buyers sharing their private information about sellers, and thus may suffer from too little feedback when provision is costly. We experimentally compare a standard feedback mechanism to one in which sellers can inspect a buyer’s feedback-provision history, thus providing incentives to share private information even when costly. We find fairly high trust and trustworthiness in all markets, with buyers providing costly feedback, especially negative, sufficient to induce trustworthiness. However, feedback-provision histories did not improve outcomes, and at least weakly decreased trustworthiness with experienced participants, as this information enabled sellers to discriminate and ship less frequently to buyers lacking a reputation for information sharing.     

EXPERIMENTAL WORK ON SUBSIDIES,MORAL HAZARD,AND MARKET POWER IN AGRICULTURAL MARKETS

Laboratory markets are created to capture the important features of agricultural commodity markets. Sellers make production decisions and hold inventories before goods are sold. In a posted‐bid auction environment, price supports create a moral hazard for sellers. Part of the price‐support subsidy is transferred to buyers in the form of lower prices, which are close to those predicted by the buyers' Cournot level. The subsidy program is expensive for this reason. Lump‐sum payments correct the moral hazard problem and are better at transferring income to sellers. However, transfers made at the beginning of each production period cause a decline in production levels. (JEL D44, C92)     

Disapproval aversion or inflated inequity acceptance? The impact of expressing emotions in ultimatum bargaining

Past experimental research has shown that when rating systems are available, buyers are more generous in accepting unfair offers in ultimatum bargaining. However, it also suggests that, under these conditions, sellers behave more fairly to avoid receiving negative feedback. This paper experimentally investigates which effect is stronger with the use of a rating system: buyers’ inflated inequity acceptance or sellers’ disapproval aversion. We explore this question by varying the information condition on the buyers’ side. Our experiment shows that in a setup where the size of the pie is common knowledge for both buyers and sellers, when a rating system is present, the sellers exhibit disapproval aversion but the buyers do not display greater acceptance of inequity. By contrast, when only sellers are aware of the size of the pie, sellers behave aggressively to exploit buyers and their behavior does not change in the presence of a rating system; however, buyers display greater acceptance of inequity when a rating system is present. We discuss how these results can be explained by a theoretical model that includes sellers’ social disapproval aversion and buyers’ disappointment aversion in addition to the players’ inequality aversion.     

The Evolutionary Stability of Auctions over Bargaining

This paper considers equilibrium in transaction mechanisms. In an environment with homogeneous buyers and sellers, which eliminates the advantage auctions possess of matching buyers and sellers, both auctions and bargaining are equilibria. However, only auctions are evolutionarily stable. This identifies a new advantage of auctions over bargaining, arising from the division of the gains from trade.Journal of Economic LiteratureClassification Numbers: C78, C73, D44.     

MEETINGS AND MECHANISMS

This article shows how meeting frictions affect equilibrium trading mechanisms and allocations in an environment where identical sellers post mechanisms to compete for buyers with ex ante heterogeneous private valuations. Multiple submarkets can emerge, each consisting of all sellers posting a particular mechanism and the buyers who visit those sellers. Under mild conditions, high-valuation buyers are all located in the same submarket, and low valuation buyers can be in: (i) the same submarket, (ii) a different submarket, and (iii) a mixture of (i) and (ii). The decentralized equilibrium is efficient when sellers can post auctions with reserve prices or entry fees.     

Dynamic sorting in durable goods markets with buyer heterogeneity

In a competitive dynamic durable good market where sellers have private information about quality, I identify certain inefficiencies that arise due to heterogeneity in buyers' valuations. Even if the market induces dynamic sorting among sellers and all goods are eventually traded, inefficiency can arise because high valuation buyers buy early when low‐quality goods are sold, while high‐quality goods are allocated to low valuation buyers that buy later. This misallocation adds to the inefficiency caused by delay in trading. Under certain circumstances, high‐quality goods may never be traded as in a static market.     

Option to wait in a search model

We consider a standard search model with buyers and sellers. Upon meeting the buyers make a take-it-or-leave-it offer, but the sellers have an option not to trade immediately but wait for more agents to appear. If more buyers come, there is excess demand, and the buyers engage in auction to get the good. Analogously, if more sellers come, the sellers engage in a Bertrand-type pricing game to sell the object. The option to wait restricts the price offer of the buyer; in an equilibrium in which trades are consummated without delay there is a unique price offer for the buyer.JEL Classification: C78, D44, D831     

WHO SEARCHES?*

We consider a directed search model with buyers and sellers and determine whether buyers look for sellers or vice versa. The buyers and sellers can choose to search or wait; what they do in equilibrium depends on the relative size of the two populations and the price formation mechanism. We study bargaining and auctions and find that when one population is much larger than the other the former searches and the latter waits. Under auction with roughly equal populations some buyers and sellers search and some wait. Our results challenge the practice of postulating who searches and who waits.     

Price discrimination of buyers with identical preferences and collusion in a model of advertising

A model of advertising and price distributions is investigated whereby each seller can contact different buyers, whose preferences are identical, with different probabilities. The model features a continuum of equilibria parametrized by the ratio of the buyers contacted by one seller—differing across “market segments”—and by the other sellers. In general, the sellers practice price discrimination across segments. More asymmetric equilibria correspond to higher volumes of transactions and higher expected transaction prices. This results in a lower expected utility for the buyers and higher expected profits; thus, identifying areas of influence can help the sellers to support collusion.     

High profit equilibria in directed search models

We consider a model of directed search where the sellers are allowed to post mechanisms with entry fees. Regardless of the number of buyers and sellers, the sellers are able to extract all the surplus of the buyers by introducing entry fees and making price schedules positively sloped in the number of buyers arriving to their shops. This is in contrast to results that are achieved for large markets under the assumption that sellers cannot influence the utility of any particular buyer (market utility assumption), in which case buyers obtain strictly positive rents. If there is a bound on the prices or on the entry fees that can be charged, then the equilibrium with full rent extraction does not exist any more, and the market utility assumption is restored for large markets.     

About market structure

I study an economy where sellers choose locations, and buyers choose which location to visit. All sellers in one location correspond to the Walrasian market while each seller in a separate location corresponds to the standard random matching model. Trades are consummated in auctions, and it turns out that the Walrasian market is not an equilibrium market structure. Rather, the sellers choose to distribute themselves in several locations endogenously creating the imperfectness of markets. I determine the number of sellers per location in equilibrium as a function of the ratio of buyers to sellers.     

Seller competition by mechanism design

This paper analyzes a market game in which sellers offer trading mechanisms to buyers and buyers decide which seller to go to depending on the trading mechanisms offered. In a (subgame perfect) equilibrium of this market, sellers hold auctions with an efficient reserve price but charge an entry fee. The entry fee depends on the number of buyers and sellers, the distribution of buyer valuations, and the buyer cost of entering the market. As the size of the market increases, the entry fee decreases and converges to zero in the limit. We study how the surplus of buyers and sellers depends on the number of agents on each side of the market in this decentralized trading environment.     

DIRECTED SEARCH,COORDINATION FAILURE,AND SELLER PROFITS: AN EXPERIMENTAL COMPARISON OF POSTED PRICING WITH SINGLE AND MULTIPLE PRICES

We experimentally examine posted pricing and directed search. In one treatment, capacity‐constrained sellers post fixed prices, which buyers observe before choosing whom to visit. In the other, firms post both “single‐buyer” (applied when one buyer visits) and “multibuyer” (when multiple buyers visit) prices. We find, based on a 2 × 2 (two buyers and two sellers) market and a follow‐up experiment with 3 and 2 × 3 markets, that multibuyer prices can be lower than single‐buyer prices or prices in the one‐price treatment. Also, allowing the multibuyer price does not affect seller profits and increases market frictions.     

Two-sided Markets,Competitive Bottlenecks and Exclusive Contracts

We provide a framework for analyzing two-sided markets that allows for different degrees of product differentiation on each side of the market. When platforms are viewed as homogenous by sellers but heterogeneous by buyers, we show that “competitive bottlenecks” arise endogenously. In equilibrium, platforms do not compete directly for sellers, instead choosing to compete indirectly by subsidizing buyers to join. Sellers are left with none of the gains from trade. Despite this, it is sellers who choose to purchase from multiple platforms (multihome). Finally, the role of exclusive contracts to prevent multihoming is explored. We are very grateful to Jose Miguel Abito for research assistance, and to the editor and a referee for helpful comments.     

Game and Simulation Experiments

When students become buyers, sellers and producers their learning of economics is accelerated. The inventor of a simulation exercise illustrates this point and comments on the need to keep the computer “hardware” from overwhelming the process of instruction.     

Confusopoly: competition and obfuscation in markets

This paper examines the effects of competition in experimental posted-offer markets where sellers can confuse buyers. I report two studies. In one, the sellers offering heterogeneous goods can obfuscate buyers by means of spurious product differentiation. In the other study, sellers offer identical goods and make their prices unnecessarily complex by having multi-part tariffs. I vary the level of competition by having treatments with two and three- sellers in both studies, and having an additional treatment with five-sellers in one study. The results show that average complexity created by a seller is not different for the treatments with two, three and five sellers. In addition, market prices are highest and buyer surplus is lowest when there are two sellers in a market.     

The existence and computation of competitive equilibria in markets with an indivisible commodity

This paper considers an exchange economy called a generalized assignment market, in which sellers and buyers trade one indivisible commodity possibly with product differentiation for a perfectly divisible commodity. The existence of a competitive equilibrium in this economy is proved using Kakutani's fixed point theorem. This existence theorem is applied to a production economy in which sellers are formulated as producers with convex cost functions. Two examples of housing markets are provided and their competitive equilibria are numerically calculated.     

Buyer groups as strategic commitments

Buyer cooperatives, buyer alliances, and horizontal mergers are often perceived as attempts to increase buyer power. In contrast to prior research emphasizing group size, I show that even small buyer groups composed of buyers with heterogeneous preferences can increase price competition among rival sellers by committing to purchase exclusively from one seller. Without transfer payments, at least one buyer group exists for each pair of sellers and buyer groups membership is chosen to achieve indifference between the two sellers. With transfer payments, and just two sellers, the grand coalition is a coalition-proof subgame perfect equilibrium (CP-SPNE), though equilibria with arbitrarily many buyer groups also exist. With three sellers (and with more sellers when the distribution of buyers is symmetric), a CP-SPNE always exists, all coalition-proof equilibria are payoff equivalent and have at least one buyer group for each pair of firms, so the grand coalition is not an equilibrium.     

The Impact of Exchange Context on the Activation of Equity in Ultimatum Games

In this paper we report the results of additional exchange ultimatum game experiments conducted at the same time as the exchange ultimatum game experiments reported in Hoffman et al. (Games and Economic Behavior, 7(3), pp. 346–380, 1994). In these additional experiments, we use instructions to change an impersonal exchange situation to a personal exchange situation. To do this, we prompt sellers to consider what choices their buyers will make. Game theory would predict that thinking about the situation would lead sellers to make smaller offers to buyers. In contrast, we find a significant increase in seller offers to buyers. This result suggests that encouraging sellers to thinking about buyer choices focuses their attention on the strategic interaction with humans who think they way they do in personal exchange situations, and who may punish them for unacceptable behavior, and not on the logic of the game theoretic structure of the problem.     

A MARKET WITH FRICTIONS IN THE MATCHING PROCESS: AN EXPERIMENTAL STUDY*

We construct a laboratory market in which there is a friction in the matching between buyers and sellers. Sellers simultaneously post prices and then buyers simultaneously choose a seller. If more than one buyer chooses the same seller, the seller's single unit is randomly sold to one of them. Our results show a broad consistency with theoretical predictions, although price dispersion exists and is slow to decay. Prices also exceed the equilibrium level when there are only two sellers, and buyers' purchase probabilities are insufficiently responsive to price differences when there are two sellers.