Buyer search and price dispersion: a laboratory study

We study markets with costly buyer search in which sellers simultaneously post prices. Buyers costlessly observe one or (with probability 1−q) two of the posted prices, and can accept one or pay to search again. The experiment varies q, the search cost, and the number of buyers. Equilibrium theory predicts a unified very low (high) price for q=0 (q=1) and predicts specific distributions of dispersed prices for q=1/3 and 2/3. Actual prices conform closely to the predictions in some treatments. Buyers’ reservation prices are biased away from the extremes, however, and sellers’ prices have positive autocorrelation and cross-sectional correlation.     

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.     

Wage and price controls in the equilibrium sequential search model

In this paper, we study the effects of wage and price controls on employment, output, and welfare in a simplified version of the Bénabou (J. Econom. Theory 60 (1993) 140) equilibrium sequential search model with bilateral heterogeneity. We show that a price ceiling increases output but the change in welfare depends on three effects: the reduction in aggregate search costs, the increase in surplus due to increased output, and the transfer of production to the least efficient firm. The model is formally identical to a standard equilibrium search model of the labor market so analogous results hold for the minimum wage.     

Nonstandard foundations of equilibrium search models

We develop an equilibrium sequential search model which includes most of the literature as special cases. In particular, the model can accommodate heterogeneity in buyers’ search costs and demand functions and firms’ cost functions, with general demand and cost functions. We identify conditions which ensure existence of equilibrium in pure strategies, utilizing recent progress in the theory of large games by Khan and Sun. These conditions elucidate the essential structure of equilibrium search models. Although we focus on sequential search, our methodology can be used for other classes of equilibrium search models as well.     

Buyer power and supplier incentives

This paper analyzes the origins and welfare consequences of buyer power. We show that if suppliers are capacity constrained or have strictly convex costs, there are two different channels through which large buyers can obtain more favorable terms from their suppliers. In particular, we show how the presence of large buyers can then erode the value of suppliers’ outside option. Somewhat surprisingly, we show how this can induce suppliers to undertake strategies that lead to higher output and potentially higher welfare.     

Equilibrium Price Dispersion in a Matching Model with Divisible Money*

The main purpose of this article is to show that, for any given parameter value, an equilibrium with dispersed prices (two‐price equilibrium) exists in Green and Zhou's matching model with divisible money. The welfare effect of price dispersion is also analyzed.     

Equilibrium Price Dispersion with Consumer Inventories

A model with two types of consumers, shoppers and captives, is constructed that leads to an equilibrium price dispersion. Shoppers may hold inventories of the good; the level of consumer inventories leads to state-dependent price dispersions. It is shown that prices and quantities display negative serial correlation. The model is tested using grocery store data, which display the predicted correlations. Journal of Economic Literature Classification Numbers: D43, L13, D83, L81.     

Consumer search with asymmetric price sampling

We explore asymmetries in the way consumers sample prices in a simple sequential search framework. In equilibrium, the price distribution of a firm catering to more local consumers first-order stochastically dominates that of its rival. Prices rise in the degree of asymmetry.     

A theory of commerce

The theory of commerce advanced here captures prominent features of retail trade: large employment, congestion effects, anonymous posted prices, and quantity discounts. This theory is built around a directed search model where buyers’ preferences are private information. The analytical solution is easily inserted in a Neoclassical growth framework. In this framework, the parameters of retail trade are calibrated using commercial margins and employment. Welfare properties depend on the sellers’ ability to charge two-tier prices. With two-tier prices, the directed search equilibrium is efficient. Otherwise, it is not. This contrasts with the full information benchmark, where directed search is always efficient.     

Entry in a Dynamic Model with Equilibrium Price Dispersion with an Application to the Market for Long-Distance Telephone Services

Models of entry based on the traditional models of oligopoly do not allow for price dispersions on homogenous products. Yet, such price dispersions do exist for homogenous products, and a firm does not lose its entire market share when it fails to charge the lowest price. Existing models of equilibrium price dispersion are not designed to analyze entry in a dynamic framework. A dynamic model is developed that allows an analysis of the effects of entry into a previously monopolized market. Despite asymmetric initial shares, the market shares of equally efficient firms tend to equalize over time. An application is the market for long‐distance telephone services following the divestiture of the bell operating companies from AT&T.     

Maximum likelihood estimation of search costs

In a recent paper Hong and Shum [2006. Using price distributions to estimate search costs. Rand Journal of Economics 37, 257-275] present a structural method to estimate search cost distributions. We extend their approach to the case of oligopoly and present a new maximum likelihood method to estimate search costs. We apply our method to a data set of online prices for different computer memory chips. The estimates suggest that the consumer population can be roughly split into two groups which either have quite high or quite low search costs. Search frictions confer a significant amount of market power to the firms: Despite more than 20 firms operating in each of the markets, we estimate price-cost margins to be around 25%. The paper also illustrates how the structural method can be employed to simulate the effects of the introduction of a sales tax.     

In pursuit of impeccable veracity

I study the institution of avoiding hiring one’s own Ph.D. graduates for assistant professorships. I argue that this institution is necessary to create better incentives for researchers to incorporate new information in studies, facilitating the convergence to asymptotic learning of the studied fundamentals.     

Costly Search, Capacity Constraints, and Bertrand Equilibrium Price Dispersion

This article analyzes the impact of transaction (search) costs and capacity constraints in an almost competitive market with homogeneous firms that compete on price. We characterize conditions under which Nash equilibria with price dispersion exist; in equilibrium, firms play pure strategies in prices and consumers adopt a symmetric mixed search strategy. Price dispersion is possible even though consumers all have the same search cost and valuation for the item and prices charged by all firms are common knowledge.     

Organizational Structure and the Choice of Price versus Quantity in a Mixed Duopoly

We consider the choice of price/quantity of a public and a private firm in a mixed differentiated duopoly. First, we study the way in which the strategic choice of the market variable is affected by different given organizational structures (managerial or entrepreneurial) of the public and the private firm. Second, we investigate how the price/quantity choice interacts with the endogenous choice of the organizational structure, thus determining a subgame perfect equilibrium at which firms choose to behave as price‐setters and to adopt a managerial structure.     

Equilibrium locations in a mixed duopoly with sequential entry in real time

We investigate a mixed duopoly model where a public firm and a private firm enter a market sequentially over an infinite time horizon, with and without uncertainty over the follower's entry date. We assume that there is a unit-length linear city and show that, if the public firm moves first, equilibrium location falls inside the second and third quartiles. The later the follower is expected to enter, the closer the two firms are. However, if the private firm acts first, it moves aggressively to locate at the middle point (one-half), forcing the public firm to locate nearer the periphery (one-sixth), to minimize consumers' transportation cost. In addition, social welfare is strictly greater when the public firm moves as the leader.     

Learning aspiration in repeated games

We study infinitely repeated symmetric 2×2 games played by bounded rational agents who follow a simple rule of thumb: each agent continues to play the same action if the current payoff exceeds the average of the past payoffs, and switches to the other action with a positive probability otherwise. By applying the stochastic approximation technique, we characterize the asymptotic outcomes for all 2×2 games. In the prisoners’ dilemma game, for example, the players cooperate in the limit if and only if the gain from defecting against cooperation is “modest.”     

Optimal guessing: Choice in complex environments

In this paper, we extend the analysis of our earlier work on boundedly rational learning in an i.i.d. setting [Easley and Rustichini, Econometrica 67 (1999) 1157-1184] to complex decision problems. We show that the axioms from our earlier analysis can be applied in this more complex setting, and along with some new axioms, they asymptotically yield expected utility maximization. Perhaps most important is our demonstration of a simple procedure that insures expected payoff maximization no matter what Markov process the underlying process on states follows. We view this result as providing a positive learning result for all worlds in which learning is possible.     

Third-Degree Price Discrimination in the Presence of Subsidies

Abstract. According to a classical result, a move from uniform pricing to third-degree price discrimination only improves welfare if total output increases. In this paper I show that the classical result fails in the presence of subsidies. This finding appears to be relevant for the pharmaceutical sector where a consumer pays a fraction of the actual drug price due to health insurance coverage.     

Equilibria in large games with continuous procedures

We study existence of equilibria in large games where players use boundedly rational procedures. The equilibria are different from Nash equilibria; the difference persists even when players use procedures for which the observations gathered in any period are used to evaluate the payoff from different actions.     

Contractual distortions in a market with frictions

This paper analyses contract design in a decentralized market environment with frictions. While principals (e.g., firms) have all contractual power, their market power is constrained as agents (e.g., workers) can choose to wait and search for better offers. We find that results depend crucially on how market frictions affect agents’ utilities. With type-independent costs of search and waiting, equilibrium contracts are always first-best. If agents are impatient and discount future payoffs, however, distortions vanish only gradually. In the latter case, we also characterize equilibrium offers and show that the market exhibits two types of externalities, both of which are absent in the case of type-independent costs of search.