关键词: 产品组合决策, 先动优势, 零售商竞争, 纳会均衡, 横向差异产品

Abstract: In this paper, the horizontal different assortment competition problem is studied with two circumstances: two retailers enter the market sequentially or simultaneously. Retailers decide their product assortment and consumer demand following the MNL (multinomial logit) model, based on which the profit function of retailers is depicted. Besides, a gradually substitute method for solving the best response is constructed, the method for solving the equilibrium in the two circumstances is given, and the results of the two circumstances are compared. The condition under which the order of retailers’ entry into the market does not affect the equilibrium result is given. The numerical results verify the effectiveness of the theoretical model. The results show that the gradual substitution method is an effective way for solving the best response and the equilibrium solution. If retailers enter the market sequentially, the equilibrium solution is unique, and the total number of products offered in the market must be not less than that when the retailers enter the market simultaneously. When the fixed utility of a product satisfies some specified conditions, the equilibrium result has nothing to do with the order of retailers’ entry into the market.

Key words: assortment decisions, first mover advantage, retailer competition, Nash equilibrium, horizontal differentiated products