We propose a model which incorporates both quality and quantity in end-users’ interactions and analyze how platforms can use quality screening to alleviate information asymmetry and motivate end-users’ participations. We address the question from theoretical and empirical perspectives. In the theory, we build a model in which two platforms compete but only one of them screens sellers’ products. We show that the quality screening influences consumers’ expectations of product quality and their choices of sellers and platforms. The resulting screening effect, together with the network and competition effects, further drives sellers to enter different platforms. The equilibrium result indicates that sellers’ incentives to join the platform that screens products follow a non-monotonic relationship with respect to the observable quality of products. We estimate the model in Alibaba’s Platforms - Tmall and Taobao. The results are consistent with the theory. Counterfactual analysis suggests quality screening benefits consumers and Alibaba.

我们提出了一个模型，该模型将质量和数量都纳入了最终用户的交互中，并分析了平台如何使用质量筛选来缓解信息不对称并激发最终用户的参与。我们从理论和经验的角度解决这个问题。从理论上讲，我们建立了一个模型，在该模型中两个平台竞争，但是只有一个平台会筛选卖家的产品。我们表明，质量筛选会影响消费者对产品质量的期望以及他们对卖方和平台的选择。由此产生的筛选效果，以及网络和竞争效果，进一步驱使卖方进入不同的平台。均衡结果表明，卖方对加入产品筛选平台的动机在产品的可观察质量方面遵循非单调关系。我们在阿里巴巴的平台（天猫和淘宝）中估算模型。结果与理论相符。反事实分析表明，质量筛选有利于消费者和阿里巴巴。