In e-commerce, retailers or sellers are often assessed by customers or buyers based on reputation information to make wise purchasing decisions. Seller reputation becomes an important credential to shadow seller future behaviour. Most existing reputation models directly aggregate the ratings provided by past buyers. However, it is well documented in practical e-commerce systems that buyers’ ratings can be distorted due to collusion, which negatively affects the applicability of these reputation models. To address this challenging problem, we propose the repurchase-and-return reputation (3R) model, which puts buyers’ ratings into context before aggregating them to compute seller reputation. It considers buyer repurchase and product return behaviour after the point in time when the particular rating was provided. Intuitively, repurchases indicate that the buyers are satisfied with the previously purchased products. Thus, their positive ratings should be given more weight. Similarly, product return behaviours indicate that buyers are dissatisfied with their previous purchasing decisions. Thus, their negative ratings should be given more weight. Based on the proposed 3R reputation model, we design a price premium for a transaction considering the post-purchase behaviour of both the buyer and seller in their transactions. The proposed model is proven capable of achieving a pure strategy Nash equilibrium, in which sellers honestly provide products and buyers prefer to return bad products and repurchase good quality products. Experimental evaluation based on extensive simulation demonstrates that our model can accurately evaluate sellers’ honesty and perform well against prevailing unfair rating attacks.

在电子商务中，零售商或卖家经常被客户或买家根据声誉信息进行评估，以做出明智的购买决定。卖家声誉成为影响卖家未来行为的重要凭证。大多数现有的声誉模型直接汇总了过去买家提供的评级。然而，在实际的电子商务系统中有充分的记载，买家的评级可能会因串通而被扭曲，这会对这些声誉模型的适用性产生负面影响。为了解决这个具有挑战性的问题，我们提出了回购和退货声誉 (3R) 模型，该模型在汇总买家的评级以计算卖家声誉之前将其置于上下文中。它考虑了在提供特定评级的时间点之后的买家回购和产品退货行为。直觉上，回购表示购买者对之前购买的产品感到满意。因此，他们的正面评价应该得到更多的重视。同样，产品退货行为表明买家对他们之前的购买决定不满意。因此，他们的负面评价应该得到更多的重视。基于提出的 3R 声誉模型，我们考虑了买卖双方在交易中的购买后行为，为交易设计了价格溢价。所提出的模型被证明能够实现纯策略纳什均衡，其中卖家诚实地提供产品，而买家更愿意退回劣质产品并回购优质产品。