Towards monetary union in the Economic Community of West African States (ECOWAS): Better policy harmonisation and greater intra-trade are needed

Since the launch of the euro in 1999, the policy aspiration of the Economic Community of West African States (ECOWAS) for monetary union has increased despite its convergence challenge. This study investigates the economic characteristics of ECOWAS for a successful and sustainable monetary union. We use cluster analysis for the period 1998–2018. The findings show that there is considerable heterogeneity in the economic characteristics of ECOWAS countries. This suggests that the countries are not yet economically ready for a regional wide monetary union. The study also revealed key variables, including inflation, exchange rate volatility, intra-regional trade, that clearly demarcate the two pre-existing monetary zones in the region. The study concludes that ECOWAS policymakers must enhance policy harmonisation and intra-regional trade.     

论企业集群的优势创造与保持:制度的视角

全球化条件下的“位置悖论”促进了企业集群的理论研究与政策应用。在本文中,笔者解释了“位置悖论”,在此基础上提出并分析了“集群悖论”。制度是企业集群竞争优势的基础,集群治理是企业集群长期竞争优势的制度基础。     

对上市公司"触网"行为的实证反思

上市公司"触网",曾是中国证券市场上令人关注的话题.那么,市场对上市公司"触网"反应之强究竟达到何种程度呢?上市公司"触网"对其经营业绩究竟有无实质性影响呢?首先,本文采用超额收益法,对我国股票市场1999年68家上市公司"触网"公告的反应进行研究.研究结果表明,市场在"触网"公告日前后具有显著正反应.继而,本文采用以财务指标为基础的因子分析法,综合评价68家上市公司"触网"前后业绩的变化,研究未发现"触网"公司整体上在"触网"前一年、当年及次年的业绩有显著变化.最后,本文采用聚类分析法,依据2000年因子得分将68家"触网"后的上市公司分为三类,揭示出三类公司的不同特征,并注意到"触网"第二年,增长型企业类占到了"触网"公司的大多数.     

空间溢出视角下的生产性服务业集聚与长三角城市群经济增长效率

本文利用空间杜宾模型实证研究了生产性服务业集聚对长三角城市群经济增长效率的影响及空间溢出效应。结果表明,生产性服务业集聚不仅能够显著提升本地区的经济增长效率,还对邻近城市具有正向的空间溢出效应,但这种影响在生产性服务业的细分行业之间存在一定异质性。进一步分析发现,生产性服务业集聚的MAR外部性和Jacobs外部性都有利于长三角城市群经济增长效率的提升,而Porter外部性对经济增长效率具有负面影响。在空间溢出效应方面,Jacobs外部性对经济发展水平相近的城市具有负向溢出效应,Porter外部性对人力资本水平相近的城市具有正向溢出效应。此外,生产性服务业与制造业协同集聚对本地区和人力资本水平相近城市的经济增长效率具有显著促进作用,但对邻近城市和经济发展水平相近城市的经济增长效率因"虹吸效应"而产生一定的抑制作用。这些研究,对如何更有针对性地加快提升长三角城市群经济增长效率,提供了有价值的理论依据。     

区域经济发展过程中产业的承接、聚集与扩散--基于对福建制鞋业发展的实证分析

发展中国家通过吸引外来投资,发展外向型经济,在推动当地经济发展的同时,却由于外资企业两头在外的经营体系,提高了国内企业进入产业的门槛,加大了产业扩散的难度.福建沿海制鞋业发展表明,承接产业转移,实现产业的扩散和本地化,需要面向国内市场,具有自主开拓市场能力的民营企业的广泛参与.     

Theoretical properties of tests for spatial clustering of count data

Testing for spatial clustering of count data is an important problem in spatial data analysis. Several procedures have been proposed to this end but despite their extensive use, studies of their fundamental theoretical properties are almost non‐existent. The authors suggest two conditions that any reasonable test for spatial clustering should satisfy. The latter are based on the notion that the null hypothesis should be rejected almost surely as the amount of spatial clustering tends to infinity. The authors show that the chisquared test and the Potthoff—Whittinghill V have both properties but that other classical tests do not.     

A mathematical comparison of the members of an infinite family of agglomerative clustering algorithms

This article presents an algebraic analysis of agglomerative clustering method algorithms, which results in a graphic portrayal of these algorithms and a classification scheme for these algorithms based on the degree of distortion perpetrated on the object space by the algorithms in each group.     

经济集聚机制研究几个问题探索

目前,经济集聚现象越来越得到经济学界及区域研究学者的广泛重视,因此本文对当前区域发展的非常关注的经济集聚现象进行探讨,并就经济集聚的概念进行深刻剖析。在此基础上,提出了有关经济集聚研究的几个有价值的新研究方向,如考虑集聚效应的城市最优增长控制,中小企业在集群中的影响作用,集群的价值链分析及价值转移分析,试图为经济集聚机制研究提供新的思路和新的观察视角。     

Mixture separation for mixed-mode data

One possible approach to cluster analysis is the mixture maximum likelihood method, in which the data to be clustered are assumed to come from a finite mixture of populations. The method has been well developed, and much used, for the case of multivariate normal populations. Practical applications, however, often involve mixtures of categorical and continuous variables. Everitt (1988) and Everitt and Merette (1990) recently extended the normal model to deal with such data by incorporating the use of thresholds for the categorical variables. The computations involved in this model are so extensive, however, that it is only feasible for data containing very few categorical variables. In the present paper we consider an alternative model, known as the homogeneous Conditional Gaussian model in graphical modelling and as the location model in discriminant analysis. We extend this model to the finite mixture situation, obtain maximum likelihood estimates for the population parameters, and show that computation is feasible for an arbitrary number of variables. Some data sets are clustered by this method, and a small simulation study demonstrates characteristics of its performance.     

Mo-S-Fe簇合物的硬脂酸彩色复合膜研究

在钢铁表面获得了具有金属光泽和良好装饰效果的不溶性彩色Mo—S-Fe簇合物膜,采用加速化学腐蚀实验、LSV、XPS和AES研究了多种钝化剂处理簇合物膜前后的耐蚀性能。结果表明,硬脂酸钝化处理后,不仅保护和稳定了膜层的颜色,而且提高了钢铁的抗腐蚀能力,硬脂酸与彩色膜表面的Fe~(2+)反应形成了一层致密的不溶性配合物膜。