An experimental comparison of two search models

Summary. We report an experiment designed to investigate markets with consumer search costs. In markets where buyers are matched with one seller at a time, sellers are predicted to sell at prices equal to buyers' valuations. However, we find sellers post prices that offer a more equal division of the surplus, and these prices tend to be accepted, while prices closer to the equilibrium prediction are rejected. At the other extreme, sellers are predicted to sell at a price equal to marginal cost when buyers are matched with two sellers at a time. Here, we find prices are closer to, but still significantly different from, the equilibrium prediction. Thus, our results support theoretical comparative static, but not point, predictions.     

DYNAMIC TRADING IN A DURABLE GOOD MARKET WITH ASYMMETRIC INFORMATION*

We analyze a dynamic version of the Akerlof–Wilson “lemons” market in a competitive durable good setting. There is a fixed set of sellers with private information about the quality of their wares. The price mechanism sorts sellers of different qualities into different time periods—prices and average quality of goods traded increase over time. Goods of all qualities are traded in finite time. Market failure arises because of the waiting involved—particularly for sellers of better quality. The equilibrium path may exhibit intermediate breaks in trading.     

Search less for a better price

In many markets, sellers must spend resources to learn the costs of providing goods/services. This paper considers consumer searches in such markets. The findings show that: (i) even with ex ante identical consumers and sellers, there is price dispersion in the equilibrium, (ii) despite price dispersion and minimal search costs, it could be optimal to search just two sellers and (iii) the optimal number of searches can increase with sellers' information costs.     

Imperfect Competition in Auction Designs

We study the competition between two owners of identical goods who wish to sell them to a pool of potential buyers. The sellers compete simultaneously setting reserve prices for their second price sealed bid auctions. Upon observing the set reserve prices, the buyers decide simultaneously in which auction to bid. We show that this game has (at least) one equilibrium and that all equilibria are inefficient: reserve prices are not driven to zero (cost). We also discuss where and why the parallel between optimal auction design and optimal pricing in the case of monopoly breaks down for oligopoly.     

Cycles and multiple equilibria in the market for durable lemons

Summary. The paper investigates the nature of market failure in a dynamic version of Akerlof (1970) where identical cohorts of a durable good enter the market over time. In the dynamic model, equilibria with qualitatively different properties emerge. Typically, in equilibria of the dynamic model, sellers with higher quality wait in order to sell and wait more than sellers of lower quality. The main result is that for any distribution of quality there exist an infinite number of cyclical equilibria where all goods are traded within a certain number of periods after entering the market. Received: December 21, 2000; revised version: September 5, 2001     

A structural model of competing sellers: Auctions and posted prices

In an original data set of goods listed for sale online, I observe that both auctions and posted prices are popular with buyers and sellers in the compact-disc market. To explain why these two mechanisms coexist, I estimate a structural model of competing sellers who differ in the value of their outside options. Buyers are allowed to value auctioned and posted-price goods differently but the estimated value distributions suggest that differences across buyers do not explain the mechanism coexistence that I observe. In contrast, differences across sellers' outside options are important: the value of the outside option segments the market with high outside-option sellers choosing to post a fixed price. There are two key forces at work that drive this empirical result. First, competition between sellers favors coexistence over an auction-only or a posted-price-only marketplace because sellers prefer to be in a market with fewer rivals. Second, sellers with more valuable outside options prefer the posted-price mechanism because posted-price goods sell less often than auctioned goods but at a higher price. As a result, a larger outside option reduces the loss from not selling and favors the posted-price mechanism.     

Information Provision in Procurement Auctions

We study the optimal provision of information in a procurement auction with horizontally differentiated goods. The buyer has private information about her preferred location on the product space and has access to a costless communication device. A seller who pays the entry cost may submit a bid comprising a location and a minimum price. We characterize the optimal information structure and show that the buyer prefers to attract only two bids. Further, additional sellers are inefficient since they reduce total and consumer surplus, gross of entry costs. We show that the buyer will not find it optimal to send public information to all sellers. On the other hand, she may profit from setting a minimum price and that a severe hold‐up problem arises if she lacks commitment to set up the rules of the auction ex ante.     

Efficiency of continuous double auctions under individual evolutionary learning with full or limited information

In this paper we explore how specific aspects of market transparency and agents’ behavior affect the efficiency of the market outcome. In particular, we are interested whether learning behavior with and without information about actions of other participants improves market efficiency. We consider a simple market for a homogeneous good populated by buyers and sellers. The valuations of the buyers and the costs of the sellers are given exogenously. Agents are involved in consecutive trading sessions, which are organized as a continuous double auction with order book. Using Individual Evolutionary Learning agents submit price bids and offers, trying to learn the most profitable strategy by looking at their realized and counterfactual or “foregone” payoffs. We find that learning outcomes heavily depend on information treatments. Under full information about actions of others, agents’ orders tend to be similar, while under limited information agents tend to submit their valuations/costs. This behavioral outcome results in higher price volatility for the latter treatment. We also find that learning improves allocative efficiency when compared to outcomes with Zero-Intelligent traders.     

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     

Randomized double auctions: gains from trade,trader roles,and price discovery

Experimental double-auction commodity markets are known to exhibit robust convergence to competitive equilibria under stable or cyclical supply and demand conditions, but little is known about their performance in truly random environments. We provide a comprehensive study of double auctions in a stochastic setting where the equilibrium prices, trading volumes and gains from trade are highly variable across periods, and with commodity traders who may buy or sell their goods depending on market conditions and their individual outcomes. We find that performance in this stochastic environment is sensitive to underlying market conditions. Efficiency is higher and convergence to the competitive equilibrium stronger when the potential gains from trade are high and when the equilibrium spans a wide range of quantities, implying a large number of marginal trades. Speculative re-trading is prevalent, especially among those who have little to gain under equilibrium pricing. Those with the largest expected gains typically earn far less than predicted, while those with little or no predicted earnings gain modestly from speculation, leading to some redistribution of gains from high to low expected earners. Excessive trading volumes are associated with negative efficiencies in markets with low gains from trade, but not in the high-gains markets, where zero-sum trading and re-trading appear to enforce efficiency and near-equilibrium pricing. Buyers earn more relative to their competitive equilibrium benchmark than sellers do. Introducing trader specialization leads to fewer trading errors and higher market efficiency, but it does not eliminate zero-sum trading and re-trading.

     

The Demand for Information Services and the Market Structure

Uninformed buyers' demand for statistical screening between privately informed sellers is studied in a fixed price market. A single buyer will screen more extensively than would two or more buyers, since in the latter case buyers realize that sellers will be attracted to buyers with the most favorable screening policy (i.e., not to screen at all). This result is robust to some but not all types of modifications in the model. For instance, information quality differences in the sense of Blackwell will reinforce this effect. Furthermore, in equilibrium only the best information service will be used. Received April 17, 2001; revised version received January 24, 2002 Published online: November 11, 2002     

Dissertation abstract: Essays on pricing in experimental duopoly markets

This dissertation comprises three independent essays that analyze pricing behavior in experimental duopoly markets. The first essay examines whether the content of buyer information and the timing of its dissemination affects seller market power. We construct laboratory markets with differentiated goods and costly buyer search in which sellers simultaneously post prices. The experiment varies the information on price or product characteristics that buyers learn under different timing assumptions (pre- and post-search), generating four information treatments. Theory predicts that price information lowers the equilibrium price, but information about product characteristics increases the equilibrium price. That is, contrary to simple intuition, presence of informed buyers may impart a negative externality on other uninformed buyers. The data support the model's negative externality result when sellers face a large number of robot buyers that are programmed to search optimally. Observed prices conform to the model's comparative statics and are broadly consistent with predicted levels. With human buyers, however, excessive search instigates increased price competition and sellers post prices that are significantly lower than predicted. The second essay uses experimental methods to demonstrate the anti-competitive potential of price-matching guarantees in both symmetric and asymmetric cost duopolies. When costs are symmetric, price-matching guarantees increase the posted prices to the collusive level. With asymmetric costs, guaranteed prices remain high relative to prices without the use of guarantees, but the overall ability of guarantees to act as a collusion facilitating device depends on the relative cost difference. Fewer guarantees, combined with lower average prices, suggest that cost asymmetries may discourage collusion. The third essay investigates the effect of firm size asymmetry on the emergence of price leadership in a homogeneous good duopoly. With discounting, the unique subgame-perfect equilibrium predicts that the large firm will emerge as the endogenous price leader. Independent of the level of size asymmetry, the laboratory data indicates that price leadership by the large firm is one of the most frequently observed timings of price announcement. In most cases, however, it comes second to simultaneous price-setting. This tendency to wait for the other firm to announce its price is especially strong when the level of size asymmetry between firms is low. We attribute the lower than expected frequency of price leadership to coordination failure, which is further compounded by elements of inequity aversion. JEL Classification C91, D43, D83, L11 Dissertation Committee: Timothy Cason (Chair), Department of Economics, Purdue University Dan Kovenock, Department of Economics, Purdue University Stephen Martin, Department of Economics, Purdue University Marco Casari, Department of Economics, Purdue University     

Winner-take-all price competition

Summary. We analyze an oligopoly model of homogeneous product price competition that allows for discontinuities in demand and/or costs. Conditions under which only zero profit equilibrium outcomes obtain in such settings are provided. We then illustrate through a series of examples that the conditions provided are “tight” in the sense that their relaxation leads to positive profit outcomes. Received: April 7, 2000; revised version: September 14, 2000     

Strategic Buyers and Privately Observed Prices

A model of finitely repeated price competition between two sellers with differentiated goods and a large buyer is analyzed. The set of pure strategy sequential equilibria is investigated under public and private monitoring. With private monitoring, i.e., when prices are not observable to the competing sellers, all sales are made by the better seller and the set of repeated game equilibrium payoffs coincides with the stage game subgame perfect equilibrium payoffs. This is in sharp contrast to the game with perfect monitoring where the folk theorem obtains. Journal of Economic Literature Classification Numbers: C72, D43.     

A Signaling Model of Multiple Currencies

In this paper, we demonstrate that it may be socially optimal for countries to have different currencies, even though they have no possibility of independently controlling their money supplies. We assume that agents have heterogeneous preferences over goods of different national origin, and that these preferences are private information. We prove three results. First, for a range of parameters, it is optimal for different countries to have different currencies so that buyers can more efficiently signal their preferences over goods to sellers. Second, if it is socially optimal to have different national currencies, then it is socially optimal for sellers to sell lower quantities to buyers bearing foreign currency. Finally, it is only necessary to have two monies if cross-country trade is optimal.Journal of Economic LiteratureClassification Number: F33     

A Two-stage Price-setting Duopoly: Bertrand or Stackelberg

This paper investigates a two-stage price-setting duopoly with differentiated goods. First, each firm announces its price; second, it chooses its actual price; and finally the market opens. Once a firm announces a price, it is able to discount it but not raise it. The model includes Stackelberg-type and Bertrand-type equilibria as possible outcomes. Whether Bertrand or Stackelberg appears in equilibrium depends on the properties of demand functions crucially. We find three patterns of equilibrium outcomes; one case has Bertrand equilibrium only, another has Stackelberg only, and the other has both equilibria     

Shrouding Add‐On Information: An Experimental Study*

We explore how increased competition affects firms’ obfuscation strategies in a laboratory experiment. Firms sell a base good and an add‐on product. Besides choosing the base‐good price, sellers take an action that mimics the effects of shrouding the add‐on product. Shrouding is an equilibrium but an unshrouding equilibrium coexists. In our experiment, more competition matters, in that only duopolistic markets are frequently shrouded whereas four‐firm markets are not. With repeated interaction, shrouding rates do not increase. However, the opportunities to shroud facilitate tacit collusion on the base‐good price for the duopolies: the unshrouding equilibrium serves as a credible punishment if deviations occur.     

Pricing and signaling with frictions

We study a market where each seller chooses the quality and price of goods and the number of selling sites. Observing sellers? choices of prices and sites, but not quality, buyers choose which site to visit. A seller?s choices of prices can direct buyers? search and signal quality. A unique equilibrium exists and is separating. When the quality differential is large, the equilibrium implements the efficient allocation with public information. Otherwise, the quality of goods and/or the number of sites created is inefficient, due to a conflict between the search-directing and signaling roles of prices.     

An ascending double auction

We show why the failure of the affiliation assumption prevents the double auction from achieving efficient outcomes when values are interdependent. This motivates the study of an ascending price version of the double auction. It is shown that when there is a sufficiently large, but still finite, number of sellers, this mechanism has an approximate perfect Bayesian equilibrium in which traders continue bidding if and only if their true estimates of the ‘value’ of the object being traded exceed the current price. This equilibrium is ex post efficient and has a rational expectations property in the sense that along the equilibrium path traders appear to have made the best possible trades conditional on information revealed by the trading process. We thank two anonymous referees and Dan Kovenock, the Editor, whose detailed comments and suggestions have allowed us to substantially improve the paper. We also thank seminar participants at University of Toronto, University of Wisconsin-Madison, Summer 2003 North American Meetings of the Econometric Society, 2004 NSF Decentralization Conference for their comments.     

Cointegration and common trends on the West German labour market

In this paper we analyze the West German labour market by means of a cointegrated structural VAR model. We find sensible stable long-run relationships that are interpreted as a labour demand, a wage setting and a goods market equilibrium. In order to study the dynamic behaviour of the model we identify two common trends that push unemployment. We find that goods market shocks have only transitory impacts on unemployment. In the long run, it is almost equally determined by technology and labour supply factors. However, transitory shocks have major importance in the shorter run since adjustment processes are rather sluggish. First version received: Sept. 1998/Final version accepted: Feb. 2000