Profitability of price and quantity strategies in a duopoly with vertical product differentiation

Using a model according to Mussa and Rosen (1978) and Bonanno and Haworth (1998) we consider a sub-game perfect equilibrium of a two-stage game in a duopolistic industry in which the products of the firms are vertically differentiated. In the industry, there are a high quality firm and a low quality firm. In the first stage of the game, the firms choose their strategic variables, price or quantity. In the second stage, they determine the levels of their strategic variables. We will show that, under an assumption about distribution of consumers' preference, we obtain the result that is similar to Singh and Vives (1984)' proposition (their Proposition 3) in the case of substitutes with nonlinear demand functions. That is, in the first stage of the game, a quantity strategy dominates a price strategy for both firms. Received: April 23, 1999; revised version: May 31, 2000     

Licensing under vertical product differentiation: Price vs. quantity competition

This paper develops a duopoly model of vertical product differentiation where two domestic firms incur variable costs of quality development. These domestic firms can purchase a superior foreign technology through licensing. Outcomes between Bertrand and Cournot competition are compared. We find that licensing raises domestic welfare, and domestic welfare is higher in Bertrand than in Cournot competition regardless of whether or not domestic firms engage in licensing. Non-exclusive licensing is also found to benefit the domestic country more than exclusive licensing.     

Price equilibrium in address models of product differentiation: unit-elastic demand

Summary. I present a class of address models of product differentiation with unit-elastic individual demand and show the existence of Nash equilibrium in prices under assumptions on utility functions and the taste and income heterogeneity across consumers. This paper complements the work by Caplin and Nalebuff (1991, Econometrica), who analyze unit demand models of product differentiation. Received: December 28, 1998; revised version: September 5, 2001     

Price versus quantity in a duopoly of vertical differentiation with loss-averse consumers

In a model à la Mussa and Rosen (1978) in which consumers are loss-averse, I check the robustness of the result obtained by Tanaka (2001). As he did, I find that the quantity contract is a dominant strategy for both firms. Thus, Cournot is the outcome in equilibrium. Finally, I find that loss aversion in general intensifies competition.     

Price competition in markets with customer testing: the captive customer effect

We introduce product differentiation into the analysis of price competition in markets where suppliers test customers in order to assess whether they will pay for received goods or services. We find that, if the degree of differentiation is sufficiently high, suppliers may improve the average probability that their clientele will pay by charging higher prices. This helps suppliers to sustain high prices in equilibrium. Moreover, endogenizing locations in product space, we demonstrate that the high price level can be implemented in a pure-strategy subgame-perfect equilibrium with a high degree of differentiation. This is in contrast to the original Hotelling model with linear travel costs where a pure-strategy subgame-perfect equilibrium fails to exist.     

Strategic incentives under vertical integration: the case of wireline-affiliated wireless carriers and intermodal competition in the US

In its review of the Cingular/AT&T Wireless merger, the FCC noted the potentially conflicting incentives of wireline-affiliated (vertically integrated) versus independent (non-integrated) wireless carriers to act as intermodal competitors in the wireline exchange access market. Specifically, because Cingular and Verizon Wireless are owned by wireline carriers, they may have an incentive to compete “less aggressively” within their parents’ wireline territories while AT&T Wireless, an independent wireless carrier, would not. This paper examines these and other hypotheses by examining pre-merger data on the wireless plans offered by the three carriers. The empirical analysis suggests that AT&T Wireless did not design its plans based upon a regional strategy, whereas Cingular offered substantially smaller-minute wireless plans within its parents’ wireline territories. However, the results also suggest that Verizon Wireless did not design its plans in a markedly different fashion within and outside of its parent’s wireline region. It is posited that these findings might reflect the differing ownership and control structures of Cingular and Verizon Wireless.      

Effect of credible quality investment with Bertrand and Cournot competition

We show how credible revelation and ability to commit to quality choice effect equilibrium qualities and welfare when product market is either Bertrand or Cournot competition. We show that results depend on the type of competition but not generally on the cost of quality function. We show that with Bertrand competition, the equilibrium qualities are lower with credible commitment. Competition is moderated and producer surplus is higher and consumer surplus lower. With Cournot competition, higher quality will be better but lower quality will be worse with credible commitment. Consumer surplus is always greater with credible commitment and if cost does not increase too quickly with quality, producer surplus will also increase. Thus credible commitment is a collusive device with Bertrand competition but it can improve social welfare with Cournot competition. Received: February 8, 2000; revised version: February 14, 2002 RID="*" ID="*" The idea of this paper originated in the weekly workshops of Mordecai Kurz at Stanford. I am forever in debted to Mordecai and fellow students – Luis Cabral, Peter DeMarzo, John Hillas, Michihiro Kandori, Steve Langois, Patrick McAllister, Steve Sharpe, Peter Streufert, Steve Turnbull and Gyu-Ho Wang – for their criticism and encouragement. I also benefited from comments from Yi-Heng Chen, Jin-Li Hu, Kala Krishna, Jinji Naoto, Thomas J. Prusa, and Shyh-Fang Ueng at various later stages of this work. Last but not least, I am grateful for the detailed comments of the referee.