Collaborative Research: An Experimental Study on Collusion and Communication

从1890年的《谢尔曼法案》（Sherman Act）到今天，防止和发现竞争公司之间的勾结一直是反垄断和合并政策的核心问题。要设计这种政策，就必须了解什么时候可能会发生串通，以及如何有效地阻止这种串通。过去的理论研究主要集中在理解串通协议可以持续一段时间的机制。相反，坊间证据表明，反垄断政策的主要影响是破坏企业达成串通协议的过程。人们对这些公司是如何达成这样的协议知之甚少，事实证明，从现场数据中识别这一点极其困难。因此，在这种环境中，实验方法可以提供否则无法获得的见解。该项目包括一系列旨在研究公司如何达成串通协议的实验。它侧重于实验对象之间为此目的的明确沟通的作用，并试图确定有助于促进勾结的沟通特征。所有的治疗都是从没有沟通的初始阶段开始的。第二阶段是允许通信的阶段。在第二阶段允许的交流类型上，治疗方法各不相同。这项研究的根本问题是，明确的沟通对于达成串通是否必不可少。在这一主题的基础上，实验设计探索了许多关于沟通的哪些特征对达成合谋结果最重要的问题：*理论表明，信息需要传达偶然的策略，但仅仅关于当前价格或数量的简单信息就足够了吗？*如果只有少数受试者最初能够遵循有效的合谋策略，那么他们与其他受试者的互动是否会“感染”其他人群并导致广泛的合谋？*是否有些人有计划地利用沟通来达到欺骗的目的？这是否会削弱“诚实”玩家达成串通协议的能力？*允许沟通重新协商的可能性会限制偶然信息的有效性吗？*复杂性如何影响沟通与合谋之间的关系？*在真正的反垄断执法中，一项不完美地针对和惩罚有关价格的沟通的政策能有效地减少共谋的发生吗？更广泛的影响：该项目的结果对反垄断政策具有重要意义。了解共谋是如何产生的，可以更容易地确定稀缺的执法资源应该集中在哪里，以及哪些市场特征应该被认为与合并中协调效应分析的评估有关。我们的一些治疗方法包括分析受试者的信息内容，以确定哪些特定的短语可能会产生串通协议。特别是，我们的实验使我们能够确定查找这些类型的消息的针对性执法是否可以有效地打击勾结。研究结果还可以通过帮助划定合法商业活动和反竞争行为之间的界限，为公司之间信息交换协议的政策提供信息。

From the Sherman Act of 1890 through today, preventing and detecting collusion among competing firms has been a central issue for anti-trust and merger policy. For the design of such policy it is essential to understand when collusion can be expected to be likely and how it can be effectively discouraged. In the past theoretical research has focused primarily on understanding the mechanisms by which a collusive agreement can be sustained over time. In contrast, anecdotal evidence suggests that the primary impact of antitrust policy is to disrupt the process by which firms reach collusive agreements. Very little is known about how firms come to such agreements and it has proved extremely difficult to identify this from field data. This is therefore an environment in which an experimental approach can provide insights that would be otherwise unavailable. The project consists of a series of experiments designed to study how firms reach collusive agreements. It focuses on the role of explicit communication between experimental subjects for this purpose and seeks to identify the features of communication that help foster collusion. All treatments start with an initial phase where no communication is available. A second phase then follows where communication is allowed. The treatments vary in the type of communication that is allowed for this second phase. The study's fundamental question is whether explicit communication is essential for achieving collusion. Expanding on this theme, the experimental design explores numerous questions about what features of communication matter most for reaching collusive outcomes:* Theory suggests that messages need to communicate contingent strategies, but will simpler messages that are only about current prices or quantities suffice? * If only a small number of subjects can initially follow effective strategies for collusion, do their interactions with other subjects "infect" the rest of the population and lead to widespread collusion?* Do some individuals systematically use communication for deceptive purposes? Can this undermine the ability of 'honest' players to achieve collusive agreements? * Does allowing the possibility of communication to renegotiate limit the effectiveness of contingent messages? * How does complexity affect the relationship between communication and collusion? * Can a policy that that imperfectly targets and punishes communications about prices as in real anti-trust enforcement effectively reduce the incidence of collusion?Broader Impact: The results of this project have important implications for anti-trust policy. Understanding how collusion arises makes it easier to determine where scarce enforcement resources should be focused and which market characteristics should be considered relevant for the assessment of coordinated effects analysis in mergers. Some of our treatments involve analyzing the content of subject's messages to determine what specific phrases are likely to yield collusive agreements. In particular, our experiments allow us to determine whether targeting enforcement on finding these types of messages can effectively combat collusion. The results of the study can also inform policy towards information exchange agreements between firms by helping to delineate the boundary between legitimate business activity and anticompetitive behavior.