Abstract: On e-commerce sites such as Walmart marketplace and Dangdang.com, retailers offer their competitors the opportunity to sell the same products on their sites. This behavior is called “e-tailer referral”. It is often assumed that companies will make optimal decisions by raising trade barriers and gaining more market share in a competitive market. However, one-way or two-way referral between retailers can promote implicit collusion, jointly setting higher retail prices and thus gaining higher profits, but the behavior harms the consumers' surplus. Nowadays, as the corporate social responsibility (CSR) increases, more and more retailers consider their own interests as well as consumer surplus, transforming into dual-purpose companies. This raises a new question: does the dual-purpose retailer change its referral strategy among other retailers?
We consider a duopoly market consisting of two e-retailers (Retailer 1 and Retailer 2), who mitigate the long-standing fierce competition by providing links to their competitors' products in their own stores. Four different strategy combinations can occur: both with referral, one without referral but the other with referral, one with referral but the other without referral, and both without referral. In addition, with an increase in corporate social responsibility in the market, retailers pay more attention to the change in consumer surplus in their decision-making process rather than just pursuing their own profit maximization. When a retailer incorporates consumer surplus into its decision making, defining it as a dual-purpose retailer, it will be a question to think about what kind of referral strategy the dual-purpose retailer will adopt. Based on previous research, we categorize consumers into three groups, G1, G2, and G. G1 and G2 are partially informed consumers who are only aware of their corresponding retailers, and G is the fully informed consumers who are aware of both retailers. The Hotelling model is used to characterize the utility that a consumer obtains from purchasing products in different markets from which demand is derived.
First, the equilibrium referral strategy is affected by the profit-sharing ratio in a benchmark model of retailers without dual purpose. As the profit-sharing ratio increases, the equilibrium referral strategies are: one without referral, one without pure strategy Nash equilibrium, and both with referral. This is because when the profit-sharing ratio is low, they cannot compensate for the loss of profits due to referral; when the profit-sharing ratio is medium, retailers prefer to adopt the same referral strategy; when the profit-sharing ratio is sufficiently high, retailers will choose referral strategy and jointly set higher prices. Second, in the single dual-purpose retailer model (Retailer 1 is dual-purpose), compared to the benchmark model, as Retailer 1 reduces retail price taking into account consumer surplus, it forces Retailer 2 to reduce its price as well. Both the demands of Retailer 1 and Retailer 2 will increase when only Retailer 1 implements referral but decreases under another referral scenario. At the same time, as Retailer 1's consumer surplus concerns increase, Retailer 1's willingness to choose the referral strategy decreases, and the space for both with referral strategy decreases, but for both without referral strategy increases, because high retail prices under the referral strategy are detrimental to consumer surplus. Finally, in both the dual-purpose retailer models, the fact that retailer 2 is also a dual-purpose retailer leads to a further reduction in retail prices for both retailers. In addition, consumer surplus will be optimal in equilibrium when both retailers are dual-purpose, followed by single dual-purpose, and the lowest when there is no dual-purpose retailer.

Key words: dual-purpose, e-tailer referral, profit-sharing ratio, consumer surplus

摘要： 研究了双目标网络零售商店内推介策略选择问题,此类零售商在追求利润的同时将消费者剩余作为其决策的一部分。本文考虑由两个网络零售商组成的双寡头市场,两个网络零售商可选择都不推介、单向推介以及都推介三种策略。首先,以无双目标零售商决策模型为基准,研究发现均衡推介策略受利润分成比例的影响,随着利润分成比例的增大均衡策略依次为都不推介,无纯策略Nash均衡和都推介策略。其次,建立单个双目标零售商和两个都为双目标零售商的决策模型,发现随着零售商消费者剩余关切程度的增大,零售商选择推介策略意愿减弱,导致都推介策略空间缩小,都不推介策略空间增大。此外,分析了三种决策模型中均衡推介策略下消费者剩余的变化情况。

关键词: 双目标, 网络零售商, 利润分成比例, 消费者剩余