Third-party Payment System and E-commerce: An Application of the Monetary Search Model

第三方支付系統成為預防網路交易中詐欺行為的新興支付方式﹐並對現有的金融機構產生強烈衝擊﹐因此本文以Lagos and Wright (2005)的貨幣搜尋模型為基礎﹐分析第三方支付系統有別於現有其他之支付方法的特點﹐強調其如何解決匿名配對市場中賣方在交易達成後可能的違約行為﹐並討論貨幣政策與經濟體既有因素對採用該系統的影響。內生的系統進入決策使得模型存在複均衡﹐包括貨幣與支付餘額並存的混合均衡。數值分析則顯示下列結果：(1)當進入第三方支付系統為內生均衡時﹐系統的引入可增加交易與改善交易條件從而提高整體經濟的福利；(2)當進入的成本增加時﹐均衡時系統的使用比例反而提升﹐顯示第三方支付系統的外部性可提高使用誘因﹐進而使人們在高成本時仍願意加入；(3)政府提高貨幣供給成長率會墊高使用第三方支付的成本﹐使得民眾仍願意加入第三方支付系統的可容忍進入成本降低；(4)其他競爭關係支付工具的特性、對違約行為的懲處與執行力等因素若使經濟體具有大量潛在的違約者﹐則第三方支付系統更易於該經濟體中存在。The third-party payment system has became a new means of payment to cope with fraud in e-commerce and caused great impact on the financial system. In this paper, a model based on Lagos and Wright (2005) is built to discuss the essence of the third-party payments while the potential default behavior in an anonymous market from the seller side was emphasized. The endogenous entry decision made it possible for the existence of multiple equilibria, including one with the coexistence of fiat money and the third-party payment balance. Numerical result showed that: (1) the introduce of P3P system can raise the total welfare, given the feasibility of endogenous entry through improving the volume and the terms of trade; (2) entry proportion increased with the raise of the entry cost, which showed that the externality of the system can raise the incentive for entering, which makes the system remaining desirable even under a higher cost; (3) raising the inflation rate will increase the cost of using the system and then decrease people''s tolerant entry cost; (4) if other economy factors, such as the existence of competitive means of payment or punishment and enforcement in the economy, created serious problem of potential default, then it is easier in this economy for the P3P system to be accepted