No abstract

This paper investigates a two-stage competition in a vertically differentiated industry, where each firm produces an arbitrary number of similar qualities and sells them to heterogeneous consumers. The number of products, qualities, prices, and the extent of the market coverage are endogenously determined. We show that when unit costs of quality improvement are increasing and quadratic, each firm has an incentive to provide a disconnected set of similar qualities approximating a continuum. The finding contrasts sharply with the single-quality outcome when the market coverage is exogenously determined. We also show that allowing for multiple qualities intensifies the level of competition, lowers the profit of each firm, and raises the consumer surplus and the social welfare in comparison to the single-quality duopoly.

This study aims to show that the product proliferation strategy in multi‐product duopoly is first‐mover advantage. We consider simultaneous and Stackelberg variety competitions. A firm producing more varieties charges a higher price, produces larger total quantities, and earns higher total revenue. When firms sequentially choose the masses of varieties and then simultaneously decide prices, the leader produces more varieties and enjoys first‐mover advantage. The masses of varieties can be regarded as strategic substitutes in the same way that quantities are. Finally, the market is likely to provide too few varieties relative to the social optimum.

This paper incorporates network externalities into a model of vertical product differentiation to examine how firms determine product quality and network size. We show that, with significant network benefits from quality improvement, the effects of network externalities differ depending on the type of competition. In response to an increase in network externalities, vertical product differentiation enlarges under price competition but shrinks under quantity competition. Moreover, under price competition, the network size of a high-quality product increases, whereas that of a low-quality product decreases for a sufficiently large extent of network externalities, resulting in a reversal in the leading position in terms of network size from the low- to the high-quality product. By contrast, the network sizes of high- and low-quality products both increase under quantity competition; moreover, the gap between their network sizes shrinks for a sufficiently large extent of network externalities.

No abstract