产业专业化、职能专业化与城市经济增长——基于中国地级单位面板数据的研究

本文利用2003—2008年中国284个地级单位面板数据,对中国城市产业专业化和职能专业化特征进行了分析,并将职能专业化指标引入动态外部性(MAR溢出、Jacobs溢出)与城市经济增长的分析框架,考察两类专业化对知识溢出进而对城市经济的影响。研究结果表明:中国城市产业专业化和职能专业化水平均较低,但表现出不断提高的趋势;在全国样本范围内,两类专业化水平与城市经济增长均呈现出显著的非线性关系,结合中国城市发展情况来看,更倾向于支持MAR溢出;分地区分规模城市中产业专业化和职能专业化引起的MAR溢出重要性各不相同。基于回归分析的结果,本文还讨论了各类城市的最优专业化水平。     

地区规模、集聚外部性与区域创新能力

采用2005-2013年中国内地30个地区（除西藏外）27个工业行业数据,构建面板门槛模型,实证检验不同地区规模下,区域内多样化集聚（Jacobs外部性）、专业化集聚（MAR外部性）和企业竞争对区域创新能力的影响。结果显示,当地区规模较小时,多样化集聚、专业化集聚与企业竞争都对区域创新能力具有显著促进作用,但随着地区规模的日益增大,多样化集聚对区域创新能力的促进作用明显减小;专业化集聚、企业竞争与区域创新能力之间存在倒U型关系。     

Effects of Mandatory Audit Firm Rotation Upon Quality of Audit： The Perception of Audit Firms Evidence From Bahrain

The objectives of this study are： （1） to explore current audit appointment practices by audit firms in Bahrain; （2） to look into the opinions of audit firms in Bahrain on potential effects provided by implementing mandatory audit firm rotation （audit quality）; and （3） to investigate audit firms＇ views in implementing mandatory audit firm rotation in Bahrain. To achieve these objectives, a questionnaire was developed and distributed to respondents that consist of all auditors working in audit firms in Bahrain. The findings indicated that there is a significant relationship between mandatory audit firm rotation and quality of audit. The study also indicated that longer partner tenure makes the auditor＇s performance lack the quality in the auditing process. The average mean for all questions of the hypothesis together is 2.73 with average standard deviation of 0.94 which is less than half of the mean. This means that there is no dispersion among respondents about the questions of the hypothesis. Also, the analysis shows that the t-value is 29.922, which is greater than the table critical value of t （1.66）, and the p-value obtained is 0.000 which is less than the value of significance at p 〈 0.05. These results confirm statistically that there is a significant relationship, so the null hypothesis is rejected and the alternative hypothesis is accepted.     

动态外部性与产业结构优化关系研究新进展

自马歇尔提出集聚概念以来,关于动态外部性与产业结构优化关系的研究就一直是学术界和现实社会关注的重点问题之一。通过对国外现有文献的梳理,从MAR外部性、Jacobs外部性、Porter外部性和集聚网络化角度来探讨产业结构优化,为进一步研究动态外部性与产业结构优化提供借鉴。     

上市公司重大资产重组的业绩改善研究

近年来，我国上市公司的重大资产重组事件频频发生。本文考察了2001年进行重大资产重组的71家上市公司，分析其重组前后的业绩变化。重大资产重组后企业盈利能力指标得到了显著改善，现金流管理、财务稳健性和经营能力指标的提高不显著。公司重组后第2年的业绩改善要高于重组后的2年平均业绩改善，表明我国上市公司的重组是实质性重组而非报表性重组。     

Modelling long-term investment returns via Bayesian infinite mixture time series models

This paper introduces the class of Bayesian infinite mixture time series models first proposed in Lau & So (2004) for modelling long-term investment returns. It is a flexible class of time series models and provides a flexible way to incorporate full information contained in all autoregressive components with various orders by utilizing the idea of Bayesian averaging or mixing. We adopt a Bayesian sampling scheme based on a weighted Chinese restaurant process for generating partitions of investment returns to estimate the Bayesian infinite mixture time series models. Instead of using the point estimates, as in the classical or non-Bayesian approach, the estimation in this paper is performed by the full Bayesian approach, utilizing the idea of Bayesian averaging to incorporate all information contained in the posterior distributions of the random parameters. This provides a natural way to incorporate model risk or uncertainty. The proposed models can also be used to perform clustering of investment returns and detect outliers of returns. We employ the monthly data from the Toronto Stock Exchange 300 (TSE 300) indices to illustrate the implementation of our models and compare the simulated results from the estimated models with the empirical characteristics of the TSE 300 data. We apply the Bayesian predictive distribution of the logarithmic returns obtained by the Bayesian averaging or mixing to evaluate the quantile-based and conditional tail expectation risk measures for segregated fund contracts via stochastic simulation. We compare the risk measures evaluated from our models with those from some well-known and important models in the literature, and highlight some features that can be obtained from our models.     

产业集聚外部性、城市网络外部性与城市生产效率——基于中国285个城市和十大城市群的多地域尺度分析

经济主体和经济活动在不同地理空间的集聚产生众多城市,城市之间的分工和经济联系形成城市网络。产业在城市的集聚可能带来集聚经济或集聚不经济,且专业化集聚与多样化集聚影响城市生产效率的机制不同,因而MAR外部性与Jacobs外部性对城市生产效率可能有不同的影响并表现出区域异质性;城市可以“借用”网络内其他城市经济集聚的外部性,但其生产资源也可能被“集聚”到其他城市,因而城市网络外部性对城市生产效率的影响具有“借用规模效应”和“集聚阴影效应”两种反向机制;城市间交通条件的改善有利于“借用规模效应”和“集聚阴影效应”的发挥,而产业功能互补性的增强会强化“借用规模效应”和弱化“集聚阴影效应”。以2003—2019年中国285个城市为样本的分析发现：在全国层面,MAR外部性与城市生产效率呈现倒U型关系,而Jacobs外部性对城市生产效率具有负向影响;城市网络外部性与城市生产效率显著负相关（“集聚阴影效应”强于“借用规模效应”）,交通条件的改善会强化而城市功能互补性的提高会弱化这种负面效应。在城市群城市与非城市群城市层面,Jacobs外部性对城市群城市生产效率的影响呈现倒U型趋势,但对非城市群城市生产效率具有负向影响;城市网络外部性对城市群城市和非城市群城市生产效率均具有正向影响,且交通条件的改善和功能互补性的提高均具有正向调节作用。在十大城市群层面,产业集聚外部性和城市网络外部性对城市生产效率的影响表现出多样化的异质性。因此,应进一步强化城市间的产业分工,提高城市功能互补性;城市群发展要注重改善内部交通条件和产业分工,并完善一体化发展体制机制;非城市群城市应找准自身产业发展的优势和定位,与其他城市形成合理分工和功能互补,并改善交通通达条件。