Model selection in random effects models for directed graphs using approximated Bayes factors

With the development of an MCMC algorithm, Bayesian model selection for the p ₂ model for directed graphs has become possible. This paper presents an empirical exploration in using approximate Bayes factors for model selection. For a social network of Dutch secondary school pupils from different ethnic backgrounds it is investigated whether pupils report that they receive more emotional support from within their own ethnic group. Approximated Bayes factors seem to work, but considerable margins of error have to be reckoned with.     

发展外部性:区位竞争优势战略定位的研究基础--以济南市为例

发展是有外部性的,既有正外部性,也有负外部性。区域发展的不平衡且差距的扩大就是发展负外部性的表现,区域经济一体多样化中竞争与合作良性互动关系就是发展正外部性的表现。文章以济南市为例,探讨了区域发展中当存在发展外部性时,一个地区如何取得区位竞争优势,化不利因素为有利因素的现实问题,这对区域发展的战略定位研究有重要意义。     

动态竞争环境下我国企业运作模式构建的思考

在全球化、信息化和个性化为主要特征的时代背景下,我国企业所面对的竞争环境越来越复杂多变。适应这种多变竞争环境的企业运作模式主要包括企业管理模块和企业经营模块的构建。     

On estimating long-run effects in models with lagged dependent variables

A common procedure in economics is to estimate long-run effects from models with lagged dependent variables. For example, macro panel studies frequently are concerned with estimating the long-run impacts of fiscal policy, international aid, or foreign investment.Our analysis points out the hazards of this practice. We use Monte Carlo experiments to demonstrate that estimating long-run impacts from dynamic models produces unreliable results.Biases can be substantial, sample ranges very wide, and hypothesis tests can be rendered useless in realistic data environments. There are three reasons for this poor performance. First, OLS estimates of the coefficient of a lagged dependent variable are downwardly biased in finite samples. Second, small biases in the estimate of the lagged, dependent variable coefficient are magnified in the calculation of long-run effects. And third, and perhaps most importantly, the statistical distribution associated with estimates of the LRP is complicated, heavy-tailed, and difficult to use for hypothesis testing. While many of the underlying problems have been long-known in the literature, the continued widespread use of the associated empirical procedures suggests that researchers are unaware of the extent and severity of the estimation problems. This study aims to illustrate their practical importance for applied research.     

Strategic visualisation tools for managing technological information

In an information economy, the effective management of a massive amount of technological information is inevitable when attempting to facilitate the decision-making process. It is an important part of selecting R&D projects and allocating budgets to promising technology development. Information visualisation is thus regarded as a critical tool in technological information management because it can provide decisive implications that the intelligence of humans cannot produce. This paper proposes six graphical forms, including a technology tree, a technology map, a technology network, a technology matrix, a technology curve, and a technology dictionary, presenting the generic form and concept of each method. Moreover, the principles and applications of such visualisation tools are suggested in order to enhance their use in practical circumstances. A case study of TFT-LCD (thin film transistor-liquid crystal display) technology will help to explain how to apply visualisation tools to strategic technology management.     

Standardization in electronic money

Abstract

Electronic money services are provided by the combination of Integrated Circuit (IC) cards and terminals. The compatibility of different brands of electronic money can be enabled by firms' joint adoption of standard terminals. In this paper, we analyse the effect of achieving compatibility among different brands of electronic money. We show that, if the unit production cost of a standard terminal is not so much different from that of a non-standard one, firms' joint adoption of standard terminals will increase the total sales of IC cards and the network size of terminals, thus raising consumers' surplus and firms' profits. On the other hand, if the unit cost of a standard terminal is so high that firms are discouraged from voluntarily adopting standard ones, the government may employ subsides to enhance efficiency. However, if the duty of implementing standardization is placed solely on the firms without subsidies, all the agents, including consumers and retailers, will be left worse off.     

企业价值网低碳共生演化的序参量控制机理研究——“后危机时代”工业发展模式转型研究

每一次经济危机都会带来产业结构的大调整,并诱发工业发展模式的大转型。本文基于协同学的研究视角,选取了企业价值网作为研究对象,研究在后危机时代企业价值网实现低碳共生演化的序参量控制机理,进一步揭示企业价值网微观运行机理,为企业及政府在后危机时代实现企业价值网的低碳共生演化和低碳发展模式转型提供决策理论依据。     

Towards Trade Equalisation: A Network Perspective on Trade and Income Convergence Across the Twentieth Century

An enduring dynamic of the twentieth century is the dramatic expansion of global trade with increased partners, goods, frequency and volumes. Most trade explanations such as the Heckscher–Ohlin, new trade theory, gravity models, and Ricardo and Sraffa focus on how bilateral import and export volumes and intermediate input goods are driven by decreased financial and information transaction costs. Extending work on trade flows and economic development, we derive several network measures of degree, betweenness and eigenvector centrality from dyadic trade flows from 1960 to 2009. We then empirically explore the interactive effects of trade connectivity, economic production and stages of development on income convergence and trade equalisation. We empirically find clear patterns towards a new phenomenon, both sigma levels and beta rates trade convergence and equalisation for our entire sample. Visualising sigma and beta convergence for seven major trading nations from 1920 to 2010, we believe offers new insights into economic development theory if only beginning to loosen the knot of trade, growth and globalisation.     

The ECFA and its expected effect on cross-strait trade and investment: a Taiwanese perspective

To come to terms with the realization of ASEAN+1, Taiwan had concluded with mainland China a special free trade agreement (FTA), the Economic Cooperation Framework Agreement (ECFA) in June 2010. This framework agreement provides an early harvest agreement of near-term tariff elimination, including detailed product schedules for goods and services from each side, with the final shape of fuller trade liberalization in goods and services taking years to negotiate and realize. The conclusion of the ECFA has been considered as a major breakthrough in cross-strait talks and economic relationships, even though it is by no means free from controversies inside Taiwan. The authors are therefore motivated by hot debates in Taiwan to reflect on the expected trade effect of the ECFA by taking into account the factor of cross-strait global production networks. In particular, we examine with a proposed model and statistical robustness, the trend of Taiwan-based firms' localization in mainland China, driven in part by constant movements in global production networks, which generates complicated and dynamic relationships between Taiwan's investment-induced trade and structural shift in Taiwan's exports to mainland China. Based on our empirical findings, we reflect on the conventional views on the trade effect of the free trade agreement. The results of our analyses tend to support a cautious view about the trade effect of the ECFA. Without denying the significance of the ECFA and deepening cross-strait economic relationships, we argue that the impact of the ECFA should be interpreted in a wider context than just the trade perspective, as the conventional wisdom and the existing evaluations suggested.     

A gossip based information fusion protocol for distributed frequent itemset mining

The computational complexity, huge memory space requirement, and time-consuming nature of frequent pattern mining process are the most important motivations for distribution and parallelization of this mining process. On the other hand, the emergence of distributed computational and operational environments, which causes the production and maintenance of data on different distributed data sources, makes the parallelization and distribution of the knowledge discovery process inevitable. In this paper, a gossip based distributed itemset mining (GDIM) algorithm is proposed to extract frequent itemsets, which are special types of frequent patterns, in a wireless sensor network environment. In this algorithm, local frequent itemsets of each sensor are extracted using a bit-wise horizontal approach (LHPM) from the nodes which are clustered using a leach-based protocol. Heads of clusters exploit a gossip based protocol in order to communicate each other to find the patterns which their global support is equal to or more than the specified support threshold. Experimental results show that the proposed algorithm outperforms the best existing gossip based algorithm in term of execution time.