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Price Discrimination

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R. Preston McAfee, Price Discrimination, in 1 ISSUES IN COMPETITION LAW AND POLICY 465 (ABA Section of Antitrust Law 2008) Chapter 20 _________________________ PRICE DISCRIMINATION R. Preston McAfee* This chapter sets out the rationale for price discrimination and discusses the two major forms of price discrimination. It then considers the welfare effects and antitrust implications of price discrimination. 1. Introduction The Web site of computer manufacturer Dell asks prospective buyers to declare whether they are a home user, small business, large business or government entity. Two years ago, the price of a 512 MB memory module, part number A0193405, depended on which business segment one declared. At that time, Dell quoted …show more content…

The first-order conditions for profit maximization entail 0 S c( p ) q( p )  ( p  c c( q ( p))) q c( p ) (2) Recall that the elasticity of demand, which measures the responsiveness of demand to price, is given by H  pq c( p ) q( p ) (3) The elasticity is not necessarily constant, but depends on p. However, this dependence is suppressed for clarity in exposition. Rearranging Equation (3) slightly, the first-order condition for profit maximization can be expressed as p  c c( q ( p )) p 1 H (4) The left-hand side of this expression is the proportion of the price which is a markup over marginal cost. It is known as the “price-cost margin.” Historically, it is also known as the “Lerner Index.” The price-cost margin matters because, in the standard neoclassical model, a competitive industry prices at marginal cost. Thus, the price-cost margin can be viewed as a measure of the deviation from marginal cost. A price-cost margin of zero means that price equals marginal cost, which is the competitive solution. A price-cost margin of ½ means the marginal cost is marked up by 100 percent—half the price is markup. The formula shows that profit maximization entails a price-cost margin of 1/H. If costs are not negative, the left-hand side is not greater than one, and profit maximization entails an elasticity at least as large as one. What happens when the elasticity is less PRICE

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