Erasmus School of Economics, Erasmus University Rotterdam, 3000 DR Rotterdam, The Netherlands
Proc Natl Acad Sci U S A. 2017 Jul 25;114(30):7958-7962. doi: 10.1073/pnas.1703486114. Epub 2017 Jul 10.
Financial markets reveal what investors think about the future, and prediction markets are used to forecast election results. Could markets also encourage people to reveal private information, such as subjective judgments (e.g., "Are you satisfied with your life?") or unverifiable facts? This paper shows how to design such markets, called Bayesian markets. People trade an asset whose value represents the proportion of affirmative answers to a question. Their trading position then reveals their own answer to the question. The results of this paper are based on a Bayesian setup in which people use their private information (their "type") as a signal. Hence, beliefs about others' types are correlated with one's own type. Bayesian markets transform this correlation into a mechanism that rewards truth telling. These markets avoid two complications of alternative methods: they need no knowledge of prior information and no elicitation of metabeliefs regarding others' signals.
金融市场反映了投资者对未来的看法，而预测市场则被用于预测选举结果。那么，市场是否也可以鼓励人们透露私人信息，如主观判断（例如，“你对自己的生活满意吗？”）或无法核实的事实？本文展示了如何设计这样的市场，称为贝叶斯市场。人们交易一种资产，其价值代表了对一个问题的肯定回答的比例。他们的交易头寸随后揭示了他们自己对这个问题的答案。本文的结果基于一个贝叶斯设置，其中人们将自己的私人信息（他们的“类型”）用作信号。因此，关于他人类型的信念与自己的类型相关。贝叶斯市场将这种相关性转化为一种奖励说实话的机制。这些市场避免了替代方法的两个复杂性：它们不需要了解先验信息，也不需要对他人信号的元信念进行启发式评估。
