A Consumer-Based Model of Diffusion
of Two Competitive, Compatible, and Durable Goods

Masaki Tomochi, Mitsuo Kono
mtomochi@uci.edu, kono@fps.chuo-u.ac.jp


     The diffusion of two competitive, interchangeable, and durable goods is studied under the framework of a spatial game where consumers are distributed on two-dimensional square lattice and play 3 by 3 symmetric coordination-like games with their nearest neighbors.  There are three strategies, either consuming a product A or B, or a strategy C of not consuming either A or B.  The payoff matrix of the game contains the effects of network externality, that is, the payoffs are dependent on the number of agents adopting the strategies A, B, or C.  Both simulations and mean-field approximation show that the existence of the effects of the network externality amplifies any slight initial difference in the number of agents who adopt either A or B and eventually promotes the superior product to take over the entire market.  On the other hand, without effects of the network externality the slight initial difference is not enlarged and both superior and inferior products are observed to coexist by forming clusters in the market.  Moreover, the effects of innovation factors that help an inferior product to retake over the market are studied. It is shown that both the timing and size of the innovation factor matter for an inferior product in order to retake the market.