效率参数不可观测下的SaaS云外包合约研究

客户企业在实施SaaS（软件即服务，Software as a Service）云外包时，面临因效率参数不可观测所引发的云服务提供商（Cloud Service Provider，CSP）道德风险问题。针对该问题，以激励机制设计方法为基础，以客户企业期望收益最大化为目标，在服务产出为公共信息，而效率参数信息为CSP私人信息下研究如何通过外包合约的设计诱使CSP显示出真实的信息，并付出最优的努力水平。研究表明，最优努力水平、服务报酬支付是效率参数的减函数；客户企业向CSP提供的最优合约可以用线性合约表示；在由固定服务报酬及收益共享构成的线性合约中，效率参数与固定服务报酬支付正相关，与收益共享系数负相关。

Research on SaaS Cloud Outsourcing Contract under Unobserved Efficiency Parameter

There exists moral hazard caused by unobserved efficiency parameter of CSP when customer enterprise is carrying out SaaS(Software as a Service) cloud outsourcing. Focused on this problem, to maximize the expected profit of customer enterprise, the outsourcing incentive mechanism is designed based on incentive mechanism design method to induce CSP to show real information and pay the optimal effort level under the circumstance of service output is the public information,but the efficiency parameter is private information. The conclusions imply that the optimal effort and service payment are the decreasing function of effectiveness parameter; the optimal contract provided by customer enterprise to CSP can be expressed by linear contract; the efficiency parameter is positively related to the payment of the fixed service payment and is negatively related to revenue sharing coefficient in the linear contract which is composed of the fixed service reward and sharing revenue.