混合双边市场中的平台定价模型研究

This project aims at building the first general pricing model for platforms operating in what we call a "mixed two-sided market", a distinctive yet prevalent market form.In mixed two-sided markets such as Taobao.com, one same user can have "double identities" - she may sometimes trade as a buyer, and sometimes as a seller. The canonical "two-sided market theory" has assumed that the two user groups of the market, one on the buying side and the other, selling, have to be strictly separated. This assumption ignores the existence of the double-identity users previously mentioned, and as a result, when applied to mixed two-sided platforms, thecanonical model will lead to improper gauge of demand from such users.Our new model completely abandons this assumption, and instead allows all users to freely participate on either one side or both sides of amarket, whichfixes the problem of demand gauge in the canonical model and renders a precise description of all user groups with single or double identities. Acknowledging the existence of double-identity users also means the platform in our model can intentionally price the services provided to such users, in addition to pricingfor onlybuyers and sellers as in the canonical model.This fundamental change enables us to provide a complete representation of the mixed two-sided platform pricing problem in the general framework of multiproduct pricing theory.Our new theory can serve as the guide book for real-life corporate platforms to finding optimal pricing strategies. It will also prove a useful general framework for research and analyses related to platform competition, consumer protection and antitrust issues in relevant markets. It can also help regulators in need of the right policies to cultivate healthy developmentin such burgeoning markets and industries.

本项目首次为混合双边市场这类广泛存在而且特点鲜明的市场形式建立一个普遍的理论定价模型，填补国内外研究空白。在淘宝网等混合双边市场中，同一个用户可以兼有买家和卖家的双重身份。原有双边市场模型假定市场的买卖两边必须严格分开，忽视了一些用户具有双重身份的特性，从而会对混合双边平台需求的衡量产生严重偏差，可能得出错误结论。本模型打破上述假设，允许所有用户自由参与市场的任何一边或者两边，准确描述了具有单一身份以及双重身份的各个用户群体，纠正了原有模型的偏差，也使得平台可以针对具有双重身份的用户进行定价，而不仅是对市场的买方和卖方定价。这个根本性的变化为混合双边平台的定价问题在多产品定价理论中找到了完整的表达。本模型可以作为平台企业制定市场战略的理论依据，也将为研究平台竞争、相关市场消费者保护与反垄断等问题提供一个普遍适用的理论框架，为相关政府部门更好的引导这类市场以及制定产业发展政策提供建议。

混合双边市场广泛存在于传统行业（比如金融服务）以及新兴行业（比如信息技术行业）之中。购物网站、社交媒介、手机平台等等混合双边平台的崛起成为当今产业经济中的新现象。这些市场中的同一个用户往往可以参与平台两边的交易，比如淘宝网的用户可以既买又卖，微信的用户也可以开设微店从事经营，等等。这种市场双边相互混合的特点使得“双边捆绑”成为平台定价的可行策略之一，它在现实中常常体现为对所有用户收取同样的接入费或者会员费。本课题建立了混合双边平台的普遍定价模型，分析平台在何种情况下有激励采取双边捆绑策略，以及如何最优的设计这种策略。我们发现，双边性和混合性在模型结果中得以非常自然的分别体现。在具有相当一般性的模型假设下，我们可以将最优定价策略的充要条件写成非常直观简洁的形式，其中双边性可以完全分离到用来表示平台从市场每一边所获得的“利润边际”(profit margin)这个变量之中，而混合性则明确的体现在条件中出现的各个需求价格弹性之中。上述的利润边际和需求价格弹性同时最终决定最优定价策略的形式，包括是否需要进行双边捆绑。此模型为研究与上述平台相关的定价策略及交易机制设计、相关市场的消费者保护与反垄断等有关的问题提供了一个普遍适用的理论工具。虽然模型具有高度的一般性，但模型结果却可以用价格弹性及利润边际等浅显易懂的经济学概念来表达，因此可以直接应用于相关平台的商业经营，也可作为监管者制定相关产业发展政策的参考依据。