We consider a finite-agent Hellwig (1980) economy with an extension to allow traders to observe their neighbors’ signals in an exogenously given social network. There are two potential approaches for traders to process observed signals: directly infer information about the fundamentals from the complete collection of observed signals, or indirectly from an average of observed signals. The two approaches lead to different information sets for traders. In this study, we investigate whether the two economies corresponding to the two approaches are equivalent in the sense that they have the same market equilibrium. For general network and signal structures, we present a necessary and sufficient condition for the equivalence, revealing that the two finite-agent economies are not equivalent in general unless the network structure and signal structure coordinate well. When traders have homogeneous preferences and the signal structure takes the classical form in the literature, we find that the two finite-agent economies are equivalent for regular graphs, but not for chain and star graphs. Finally, for the classical signal structure, we show that the two large economies, defined as the limit of a sequence of replica finite-agent economies, are equivalent for any network structure.

我们考虑了有限代理人Hellwig（1980）的经济，它的扩展允许交易者在一个外源给定的社交网络中观察邻居的信号。交易者有两种潜在的方法来处理观察到的信号：直接从观察到的信号的完整集合中推断基本面的信息，或间接从观察到的信号的平均值中推断出基本面信息。两种方法为交易者提供了不同的信息集。在这项研究中，我们调查了两种方法对应的两个经济体在相同的市场均衡意义上是否相等。对于一般的网络和信号结构，我们提出了等效的必要条件和充分条件，揭示了除非网络结构和信号结构协调良好，否则这两个有限主体经济体通常并不等同。当交易者具有同质的偏好并且信号结构采用文献中的经典形式时，我们发现两个有限代理经济体对于正则图是等效的，但对于链图和星形图则不是。最后，对于经典信号结构，我们表明两个大型经济体（定义为副本有限代理经济体序列的极限）对于任何网络结构都是等效的。