The lexicographic composition of abstract games

The lexicographic composition of reflexive and complete binary relations (which are often called abstract games) is studied. The necessary and sufficient conditions are obtained for a lexicographic composition of quasi transitive relations to be quasi transitive.The case of acyclicity of lexicographic composition of two relations is also investigated. Received: September 25, 2000; revised version: November 28, 2000     

New product adoption in social networks: Why direction matters

Marketing managers and researchers generally agree that analyzing data from social networks and using them to influence consumers' purchase decisions are useful strategies. However, not all social network data may identify the most influential customers. This empirical study of more than 300 students reveals the low explanatory power of friendship networks (e.g., Facebook) and undirected-advice networks (e.g., LinkedIn). Only directed-advice networks (e.g., Google +) clearly identify influential consumers. In addition, the results challenge conventional wisdom that firms should target advisers assuming that they have the strongest influence on new product adoption. This study contradicts this common assumption and reveals that structural equivalence drives product adoption more than cohesion because advisees' adoption pressures advisers to purchase the product as well. Finally, the study shows the value of social network data beyond the traditional ego-centric psychographic metrics, such as innovativeness or opinion leadership.     

用收敛类刻划第一可数公理

本文用收敛类诱导出满足第一可数公理的拓扑空间,并得到一个拓扑空间满足第一可数公理的充要条件。     

Input-output models, directed graphs and flows in networks

This article demonstrates that a dual pair of input-output price and quantity models, taken together, constitutes a composite network flow model. The network flow model has become a dominant analytical tool within the fields of operations analysis and electrical engineering, and the aim of the article is to enable input-output users within non-standard applications to take advantage of the large body of literature within these disciplines. Through a simple example it is shown that the solution of a dual pair of input-output models is a special case of the general problem of finding a minimum cost circulation in a transportation network. Second, it is shown that the common method of determining quantities and prices in input-output models is identical to the classical node method for determination of currents and voltages in an electrical network. The theory of transportation networks offers well developed methods for analysis of capacity constraints on the network flows, while the theory of electrical networks supplies methods for analysis of models with price sensitivities and for dynamic analysis. In addition, the elegant symmetry of currents and voltages in electrical networks contributes significantly to a better understanding of the logical relationship between price and quantity models.     

中国输出了“通货紧缩”或“通货膨胀”?

本文首次采用最新发展的有向无环图等技术方法,对中国是否输出通货紧缩以及是否输出通货膨胀这一问题展开综合性、系统性的研究。研究结果表明,在通货膨胀的国际传递中,作为世界第一大经济实体的美国发挥着主导作用,与此同时,无论是在中国通货紧缩时期还是在通货膨胀时期,中国对各主要贸易伙伴国物价水平的冲击均十分微小,因此,中国并非全球通货紧缩或通货膨胀的引发因素。在此研究过程中,最新发展的有向无环图技术等方法的综合运用,在很大程度上增强了本文分析结论的可靠性与合理性。     

考虑影响不对称性的创新扩散与网络结构协同演化建模：基于信息熵与累积优势的仿真研究

创新扩散发生于社会系统中并通常与社会系统存在交互作用。网络是体现社会系统的重要手段，但已有研究中的扩散网络多为无向网络且具有静态或外生动态性质，上述处理方式忽视或无法体现扩散与以网络形式出现的社会系统的协同演化以及个体间的不对称影响。基于有向网络，提出能够体现创新扩散与网络协同演化的描述性框架，从信息搜寻与降低认知失调视角出发，基于信息熵与累积优势机制，在个体层面构造网络演化与创新采纳数学模型。在RepastSimphony2.7开发平台下，利用基于Java的智能体建模方法展开系统仿真实验。基于实验数据的描述性结果揭示，动态网络与静态网络下的创新扩散存在显著不同，网络结构演化将强化节点出度的不均衡状况，更优的扩散结果往往与更不均衡的节点出度分布同时出现，其它因素包括大众传播与人际传播等也会影响扩散与网络的协同演化；交互作用存在于控制变量间。推断性结果确认了控制变量影响与交互作用的普遍存在。     

Australian Financial Graphs: An Empirical Study

The use of graphs to disclose financial information in corporate annual reports represents a significant dimension of financial disclosure management. This study replicates and extends previous research into financial graphs by documenting the nature and extent of graph use and departures from representational neutrality among the 1991 corporate annual reports of the top one hundred companies listed on the Australian Stock Exchange. Eighty-nine per cent of companies use graphs; the mean number is 9.4, with diversified companies using the most graphs. The most commonly graphed financial variables are sales, profit, EPS and DPS. Evidence is found that graph use is contingent upon favourable performance. In addition, material measurement distortion is found in 34 per cent of all key financial graphs. Eighty-six per cent of companies have slope parameters which depart more than 10° from the optimum, thus impairing communicative effectiveness. A range of design strategies are employed which are consistent with the adoption of an impression management schema. No persistent systematic differences between forms of distortion and industry group are found. Comparison with prior single-country studies reveals that graphs are used more extensively in Australia than in the U.S.A., the U.K. or Canada, but that there is less evidence of impression management. This latter finding is consistent with the view that there are fewer short-term and capital-market pressures in Australia.     

Seeing and Doing: the Concept of Causation

This note is an extended review of the book by Judea Pearl (2000) on causality, in which the basic concepts therein are explained in a form that statisticians will hopefully appreciate, including some comments on their relevance to inference and decision-making.     

A representation of consistent binary relations

We give sufficient conditions for the existence of a numerical representation which is equivalent to consistency as defined by Suzumura (Economica 43:381–390).      

CPI、REI、PPI和房地产价格传导研究——来自上海的实证数据

本文基于上海价格指数数据研究居民消费价格指数(CPI)、原材料燃料动力购进价格指数(REI)和工业品出厂价格指数(PPI)及房地产销售价格指数的传导效应。通过DAG技术和多元动态因果检验,给出4种价格指数的同期因果流,揭示它们之间的因果联系和信息传导。实证研究表明,PPI对CPI长期传导效应显著,房地产销售价格指数对CPI有一定的弱传导效应。我国应重新编制CPI,提高居住类权重。