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Multiproduct Duopoly with Vertical Differentiation


  • Yi-Ling Cheng

    (Department of Economics, National Taiwan University)

  • Shin-Kun Peng

    (Academia Sinica and National Taiwan University)

  • Takatoshi Tabuchi

    (Faculty of Economics, University of Tokyo)


The paper investigates a two-stage competition in a vertical differentiated industry, where each firm produces an arbitrary number of similar qualities and sells them to heterogeneous consumers. We show that, when unit costs of quality are increasing and quadratic, each firm has an incentive to provide an interval of qualities. The finding is in sharp contrast to the single-quality outcome when the market coverage is exogenously determined. We also show that allowing for an interval of qualities intensifies competition, lowers the profits of each firm and raises the consumer surplus and the social welfare in comparison to the single-quality duopoly.

Suggested Citation

  • Yi-Ling Cheng & Shin-Kun Peng & Takatoshi Tabuchi, 2010. "Multiproduct Duopoly with Vertical Differentiation," CIRJE F-Series CIRJE-F-739, CIRJE, Faculty of Economics, University of Tokyo.
  • Handle: RePEc:tky:fseres:2010cf739

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    References listed on IDEAS

    1. Gilbert, Richard J & Matutes, Carmen, 1993. "Product Line Rivalry with Brand Differentiation," Journal of Industrial Economics, Wiley Blackwell, vol. 41(3), pages 223-240, September.
    2. Wauthy, Xavier, 1996. "Quality Choice in Models of Vertical Differentiation," Journal of Industrial Economics, Wiley Blackwell, vol. 44(3), pages 345-353, September.
    3. Bonnisseau Jean-Marc & Lahmandi-Ayed Rim, 2006. "Vertical Differentiation: Multiproduct Strategy to Face Entry?," The B.E. Journal of Theoretical Economics, De Gruyter, vol. 6(1), pages 1-14, November.
    4. Motta, Massimo, 1993. "Endogenous Quality Choice: Price vs. Quantity Competition," Journal of Industrial Economics, Wiley Blackwell, vol. 41(2), pages 113-131, June.
    5. Gayer Amit, 2007. "Oligopoly, Endogenous Monopolist and Product Quality," The B.E. Journal of Theoretical Economics, De Gruyter, vol. 7(1), pages 1-21, August.
    6. Mussa, Michael & Rosen, Sherwin, 1978. "Monopoly and product quality," Journal of Economic Theory, Elsevier, vol. 18(2), pages 301-317, August.
    7. Jean Tirole, 1988. "The Theory of Industrial Organization," MIT Press Books, The MIT Press, edition 1, volume 1, number 0262200716, January.
    8. K. Sridhar Moorthy, 1988. "Product and Price Competition in a Duopoly," Marketing Science, INFORMS, vol. 7(2), pages 141-168.
    9. Choi, Chong Ju & Shin, Hyun Song, 1992. "A Comment on a Model of Vertical Product Differentiation," Journal of Industrial Economics, Wiley Blackwell, vol. 40(2), pages 229-231, June.
    10. K. Sridhar Moorthy, 1984. "Market Segmentation, Self-Selection, and Product Line Design," Marketing Science, INFORMS, vol. 3(4), pages 288-307.
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    Cited by:

    1. Sun, Shaoyan & An, Henry, 2013. "Reputation and Multiproduct-firm Behavior: Product Line and Price Rivalry Among Retailers," 2013 Annual Meeting, August 4-6, 2013, Washington, D.C. 151146, Agricultural and Applied Economics Association.
    2. Müller, Stephan & Götz, Georg, 2014. "Quality competition and entry deterrence: When to launch an extra brand," Center for European, Governance and Economic Development Research Discussion Papers 223, University of Goettingen, Department of Economics.
    3. Evdokia Dritsa & Eleftherios Zacharias, 2012. "Price Competition in a Duopoly Characterized by Positional Effects," Working Papers 12-21, NET Institute.
    4. Yi-Ling Cheng & Shin-Kun Peng, 2014. "Price competition and quality differentiation with multiproduct firms," Journal of Economics, Springer, vol. 112(3), pages 207-223, July.

    More about this item

    JEL classification:

    • D21 - Microeconomics - - Production and Organizations - - - Firm Behavior: Theory
    • D43 - Microeconomics - - Market Structure, Pricing, and Design - - - Oligopoly and Other Forms of Market Imperfection
    • L11 - Industrial Organization - - Market Structure, Firm Strategy, and Market Performance - - - Production, Pricing, and Market Structure; Size Distribution of Firms
    • L13 - Industrial Organization - - Market Structure, Firm Strategy, and Market Performance - - - Oligopoly and Other Imperfect Markets

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