Examination of the poverty-environmental degradation nexus in Sub-Saharan Africa

The relationship between environmental degradation and poverty has increasingly become the focus of national strategic decision-making in recent years.However,despite several theoretical explorations on the nexus,a dearth of empirical literature on the poverty-environmental degradation nexus,specifically on Sub-Saharan Africa(SSA),still exists.In this study,we investigated the poverty-environmental degradation nexus in SSA.We hypothesized that poverty is both a cause and effect of environmental degradation,and this relationship is explained as a vicious cycle.Unlike previous studies,we employed several alternative indicators of environmental degradation to examine the poverty-environmental degradation nexus in this study.We used data from 41 countries of SSA between 1996 and 2019 and employed the generalized method of moments(GMM)approach.The findings suggest a cyclical relationship between poverty and environmental degradation in SSA,which confirms that an increase in poverty leads to an increase in environmental degradation,especially in deforestation and PM2.5 emissions.Similarly,the increase in environmental degradation positively affects poverty in SSA.We also confirmed that exogenous conditioning factors such as population growth rate,education,industrialization,and income inequality,institutional quality indicators such as governance effectiveness,control of corruption,freedom ad civil liberty,and democracy,and endogenous factors including fossil fuel energy use,fuelwood energy use,household health expenditure,infant mortality rate,and agriculture productivity influence the nexus between poverty and environmental degradation.The findings on the relationship between poverty and environmental degradation in SSA are a testimonial evidence that both poverty and environmental degradation are significant issues in SSA.Hence,poverty alleviation policies in SSA should not lead to PM2.5 emissions and deforestation,which may as well force people into a poverty-environmental degradation trap.Instead,poverty reduction policies should simultaneously achieve environmental conservation.

Some Additional Moment Conditions for a Dynamic Count Panel Data Model with Predetermined Explanatory Variables

This paper proposes some additional moment conditions for the linear feedback model with explanatory variables being predetermined, which is proposed by [1] for the purpose of dealing with count panel data. The newly proposed moment conditions include those associated with the equidispersion, the Negbin I-type model and the stationarity. The GMM estimators are constructed incorporating the additional moment conditions. Some Monte Carlo experiments indicate that the GMM estimators incorporating the additional moment conditions perform well, compared to that using only the conventional moment conditions proposed by [2,3].

Dividend Payments with a Hybrid Strategy in the Compound Poisson Risk Model

In this paper, a hybrid dividend strategy in the compound Poisson risk model is considered. In the absence of dividends, the surplus of an insurance company is modelled by a compound Poisson process. Dividends are paid at a constant rate whenever the modified surplus is in a interval;the premium income no longer goes into the surplus but is paid out as dividends whenever the modified surplus exceeds the upper bound of the interval, otherwise no dividends are paid. Integro-differential equations with boundary conditions satisfied by the expected total discounted dividends until ruin are derived;for example, closed-form solutions are given when claims are exponentially distributed. Accordingly, the moments and moment-generating functions of total discounted dividends until ruin are considered. Finally, the Gerber-Shiu function and Laplace transform of the ruin time are discussed.

市场激励型环境规制与区域绿色创新效率——基于产业结构优化的中介作用和财政分权的调节作用

市场激励型环境规制是解决环境治理负外部性、推进区域绿色创新效率的重要途径。以2005~2020年省级面板数据为研究对象,采用系统广义矩模型(GMM)法检验市场激励型环境规制对区域绿色创新效率的影响效应及作用机理。结果表明:市场激励型环境规制能够显著促进区域绿色创新效率的提升;从影响机制来看,市场激励型环境规制可以通过促进产业结构合理化和产业结构高级化显著促进区域绿色创新效率的提升。此外,有效的财政分权环境能够正向调节市场激励型环境规制与区域绿色创新效率的关系。

带支撑广义Maxwell粘弹性阻尼耗能结构风振响应分析

工程中粘弹性阻尼器的安装通过支撑与结构进行连接,但在安装粘弹性阻尼器的耗能结构随机响应分析中,为了简化计算过程,将支撑的刚度看作无穷大或者忽略支撑刚度的影响。实际上,对支撑刚度的影响加以考虑更能符合工程实际。针对考虑支撑刚度影响的粘弹性阻尼耗能结构风振响应分析过程复杂的问题,提出了一种求解考虑支撑影响的广义Maxwell粘弹性阻尼耗能结构基于Davenport谱风振响应的简明解析解法。在广义Maxwell粘弹性阻尼器微分型本构模型基础上,给出了考虑支撑刚度的粘弹性阻尼器等效本构关系。将粘弹性阻尼器等效本构关系与结构运动方程联立,采用复模态法将其解耦,获得结构风振响应的统一表达式。将耗能结构在Davenport风速谱下的系列响应功率谱密度函数分解为频域响应函数与Davenport功率谱密度函数的乘积形式,基于随机振动理论中谱矩的定义,对响应功率谱密度函数积分后获得无积分项的系列响应谱矩表达式。在算例中通过与虚拟激励法计算结果对比,验证了所提解法的准确性,并分析了支撑刚度在耗能系统中的影响。

新常态下产业结构变动与经济增长——基于省级动态面板数据的GMM方法

新常态下,正确处理好稳增长与调结构的关系,有重要的政策含义。文章通过构建NAV、MLI两个不同的产业结构变动指数,基于省级1993-2013年的面板数据,运用GMM方法进行了实证检验。结果表明:从全国范围来看,短期内,产业结构变动与经济增长之间存在双向格兰杰因果关系,而较长时期内,仅存在经济增长到产业结构变动的单向格兰杰因果关系。其次,从省级层面来看,产业结构变动与经济增长之间的格兰杰因果关系表现出很大的异质性。基于此结论,文章认为,产业政策并不具有较长时期有效性,产业政策的制定需要视期限、地区的不同而择机、择时制定;同时,要规避产业政策缺陷带来的不足,规避"结构负利"的出现。

基于GMM区分性训练方法的语言辨识系统

文章给出了一种新的语言辨识系统,该系统基于高斯混合模型的区分性训练算法。该区分训练算法在估计模型参数时,采用了广义概率下降法(GPD)和最小分类误差准则(MCE)。利用OGI多语言电话语料库对算法进行了测试,实验表明,该算法是进行语言辨识的一种有效方法。

我国市场化进程中的工资形成机制——基于动态面板数据Sys-GMM方法的实证研究

文章使用动态面板数据对我国1992-2008年的工资形成机制进行了实证研究。结果表明,我国工资形成存在较强的粘性特征,工资变动对上年工资的依赖性较强;劳动生产率对工资有一定影响,但两者的联系还很不充分;工资对反映劳动力市场供求关系的失业率反应不敏感;利润对工资有一定负效应,说明企业利润增长可能是以挤占工资为代价的;东、中、西部地区的工资形成机制存在一定差异。这些结果表明我国工资形成机制的市场化水平还不高。最后,在实证分析的基础上提出提高工资形成机制市场化水平,建立工资正常增长机制的对策建议。

欠发达地区金融发展与经济增长的实证研究:基于面板数据模型的GMM估计结果

当前,金融发展理论仍在不断深入、细化地向前发展。使用1998——2005年的截面数据考察股票市场和银行系统对欠发达地区经济增长的影响,同时利用广义矩(GMM)技术对动态面板数据进行估计。研究结果表明,在欠发达地区,由于股票市场规模的狭小,其对经济增长的影响不显著;银行体系在经济增长的过程中也没能有效地发挥其推动作用。金融总量不足、结构不合理以及金融机构治理结构混乱,制约了欠发达地区金融发展对经济增长的促进作用。

一类近似因子模型的GMM估计及其统计性质研究

对于一类异质性误差项存在截面相关性的近似因子模型,本文首先提出了估计共同因子向量和因子载荷矩阵的广义矩估计方法(GMM),该方法推广了Doz等(2012)的极大似然估计方法;其次,分别研究了模型参数广义矩估计的渐近性质和有限样本的统计性质,在适当的条件下,证明了参数的GMM估计是具有渐近正态分布的一致估计;最后,利用近似因子模型对我国各类上市公司增长性的共同驱动因素及其差异性进行了实证分析。

服务贸易的就业效应及影响因素研究——基于动态面板数据模型的GMM估计

基于全国省级动态面板数据,运用系统广义矩估计方法,对服务贸易的就业效应及其影响因素进行实证研究。结果表明,服务出口对就业具有正向促进作用,进口对就业具有负向影响,但是出口就业的促进效应大于进口就业的替代效应。第三产业产出增长能够显著促进就业,而工资、国有企业就业人数占比会显著抑制就业,利率影响不显著。如何大力发展服务贸易等由此成为促进就业增长的有力措施。

Modeling the dynamic performance of transportation infrastructure using panel data model in state-space specifications

In this study,different modeling approaches used in panel data for performance forecast of transportation infrastructure are firstly reviewed,and the panel data models(PDMs)are highlighted for longitudinal data sets.The state-space specification of PDMs are proposed as a framework to formulate dynamic performance models for transportation facilities and panel data sets are used for estimation.The models could simultaneously capture the heterogeneity and update forecast through inspections.PDMs are applied to tackle the cross-section heterogeneity of longitudinal data,and PDMs in state-space forms are used to achieve the goal of updating performance forecast with new coming data.To illustrate the methodology,three classes of dynamic PDMs are presented in four examples to compare with two classes of static PDMs for a group of composite pavement sections in an airport in east China.Estimation results obtained by ordinary least square(OLS)estimator and system generalized method of moments(SGMM)are compared for two dynamic instances.The results show that the average root mean square errors of dynamic specifications are all significantly lower than those of static counterparts as prediction continues over time.There is no significant difference of prediction accuracy between state-space model and curve shifting model over a short time.In addition,SGMM does not obtain higher prediction accuracy than OLS in this case.Finally,it is recommended to specify the inspection intervals as several constants with integer multiples.

财政分权、税收竞争与制造业高质量发展——基于变异系数-系统GMM的估计

研究国内财政分权体制和地方政府税收竞争对制造业高质量发展的影响机理及其效应,对制造业高质量发展新路径的形成具有重要意义。文章在构建多维评价指标体系的基础上,依据中国30个省级行政区面板数据,对制造业高质量发展指数进行变异系数处理,并从财政收入分权和财政支出分权双重视角构建系统GMM估计模型,检验财政分权体制下税收总量竞争和税收结构竞争对制造业高质量发展的影响。结果表明:样本考察期内,中国制造业高质量发展指数呈“波浪式”上升趋势,2009-2015年中国制造业高质量发展指数较低,2016-2019年制造业高质量发展指数快速上升;整体上,财政分权与制造业高质量发展呈负相关关系;财政分权体制下,税收总量竞争显著抑制制造业高质量发展,增值税竞争促进制造业高质量发展,企业所得税竞争抑制制造业高质量发展。文章从优化财政分权体制、规范税收优惠政策、实行地区差异化税收政策等角度,提出提升制造业高质量发展的政策建议。

商业模式框架下利益相关者满足与企业价值关系研究——来自我国教育传媒行业上市公司面板数据的系统GMM估计

在广义虚拟经济背景下,商业模式的重要性逐渐引起各方关注,但由于缺乏对其构成要素之间关系的深入研究,商业模式理论的应用受到限制。本文在商业模式理论框架下,对其构成要素中利益相关者与企业价值之间的关系进行深入探讨,指出利益相关者的满足是影响商业模式中企业价值的关键变量;在此基础上,采用动态面板模型系统GMM方法对我国教育传媒行业上市公司的数据进行实证分析,结果表明利益相关者满足与企业价值显著相关。

纵向数据广义部分线性模型的惩罚GMM估计

对纵向数据的部分线性模型,通常的做法是用样条方法或者核方法逼近非参数部分,然后再用广义估计方程的估计方法去估计参数部分.本文使用P-样条拟合非参数函数,对不同的矩条件用不同的广义矩方法对模型的参数和非参数进行估计,并且给出了估计量的大样本性质;并用计算机模拟和实例证明了当模型中存在不同的矩条件时,采用不同的惩罚广义矩方法可以显著地提高估计精度.

动态因子模型的广义矩估计(GMM)及其统计性质研究

对于一类存在截面相关性的动态因子模型,本文首次分别提出了动态因子向量和因子载荷矩阵的广义矩估计方法(GMM),该方法是对传统频域分析方法的补充;其次,分别研究了模型参数广义矩估计量的渐近性质和有限样本性质。研究发现,在适当的条件下,动态因子及其因子载荷矩阵的GMM估计不仅是具有渐近正态分布的一致估计,而且具有良好的有限样本性质。最后,本文利用动态因子模型对我国6大类上市公司盈利能力增长性的共同驱动因素及其差异性进行了实证分析。

带常数项的向量误差校正模型的GMM估计方法

将Quintos研究的一类不带常数项的协整向量的GMM估计推广到带常数项的协整向量的GMM估计 ,利用Johansen的降秩估计法得到了参数的估计、渐近性分布。文中所得的结论包括了Johansen和Quintos两文中的结论。

利用GMM逼近的协整分析推广

将Quintos研究的一类向量误差校整模型,推广到其协整向量满足某种线性限制的情形,并讨论协整向量的收敛性和 极限分布,得到了相应的结论。

Small Sample Estimation in Dynamic Panel Data Models: A Simulation Study

We used simulated data to investigate both the small and large sample properties of the within-groups (WG) estimator and the first difference generalized method of moments (FD-GMM) estimator of a dynamic panel data (DPD) model. The magnitude of WG and FD-GMM estimates are almost the same for square panels. WG estimator performs best for long panels such as those with time dimension as large as 50. The advantage of FD-GMM estimator however, is observed on panels that are long and wide, say with time dimension at least 25 and cross-section dimension size of at least 30. For small-sized panels, the two methods failed since their optimality was established in the context of asymptotic theory. We developed parametric bootstrap versions of WG and FD-GMM estimators. Simulation study indicates the advantages of the bootstrap methods under small sample cases on the assumption that variances of the individual effects and the disturbances are of similar magnitude. The boostrapped WG and FD-GMM estimators are optimal for small samples.

中国被诉反倾销寒蝉效应分析——基于引力模型的系统GMM估计

基于2001~2011年国外反倾销面板案件数据，构造以同期对华反倾销最多的27个国家或地区为截面的动态面板数据模型，应用系统GMM模型实证分析国外对华反倾销对中国总出口的影响。结果显示。国外对华反倾销调查并没有抑制中国出口，而反倾销措施对中国总出口有明显的负面影响。总的来看，国外对华反倾销使得中国总出口明显下降，中国被诉反倾销寒蝉效应显著存在。