Marotta Luca, Miccichè Salvatore, Fujiwara Yoshi, Iyetomi Hiroshi, Aoyama Hideaki, Gallegati Mauro, Mantegna Rosario N
Dipartimento di Fisica e Chimica, Università di Palermo, Palermo, Italy.
Graduate School of Simulation Studies, The University of Hyogo, Kobe, Japan.
PLoS One. 2015 May 1;10(5):e0123079. doi: 10.1371/journal.pone.0123079. eCollection 2015.
We investigate the networked nature of the Japanese credit market. Our investigation is performed with tools of network science. In our investigation we perform community detection with an algorithm which is identifying communities composed of both banks and firms. We show that the communities obtained by directly working on the bipartite network carry information about the networked nature of the Japanese credit market. Our analysis is performed for each calendar year during the time period from 1980 to 2011. To investigate the time evolution of the networked structure of the credit market we introduce a new statistical method to track the time evolution of detected communities. We then characterize the time evolution of communities by detecting for each time evolving set of communities the over-expression of attributes of firms and banks. Specifically, we consider as attributes the economic sector and the geographical location of firms and the type of banks. In our 32-year-long analysis we detect a persistence of the over-expression of attributes of communities of banks and firms together with a slow dynamic of changes from some specific attributes to new ones. Our empirical observations show that the credit market in Japan is a networked market where the type of banks, geographical location of firms and banks, and economic sector of the firm play a role in shaping the credit relationships between banks and firms.
我们研究了日本信贷市场的网络特性。我们的研究是使用网络科学工具进行的。在研究过程中，我们使用一种算法进行社区检测，该算法可识别由银行和企业组成的社区。我们表明，直接在二分网络上进行操作所获得的社区携带了有关日本信贷市场网络特性的信息。我们的分析是针对1980年至2011年期间的每个日历年进行的。为了研究信贷市场网络结构的时间演变，我们引入了一种新的统计方法来跟踪检测到的社区的时间演变。然后，我们通过检测每个随时间演变的社区集的企业和银行属性的过度表达来表征社区的时间演变。具体而言，我们将企业的经济部门、地理位置以及银行类型视为属性。在我们长达32年的分析中，我们发现银行和企业社区属性的过度表达具有持续性，同时从某些特定属性到新属性的变化动态较为缓慢。我们的实证观察表明，日本的信贷市场是一个网络市场，其中银行类型、企业和银行的地理位置以及企业的经济部门在塑造银行与企业之间的信贷关系中发挥着作用。
