A bivariate space-time downscaler under space and time misalignment

Ozone and particulate matter PM(2.5) are co-pollutants that have long been associated with increased public health risks. Information on concentration levels for both pollutants come from two sources: monitoring sites and output from complex numerical models that produce concentration surfaces over large spatial regions. In this paper, we offer a fully-model based approach for fusing these two sources of information for the pair of co-pollutants which is computationally feasible over large spatial regions and long periods of time. Due to the association between concentration levels of the two environmental contaminants, it is expected that information regarding one will help to improve prediction of the other. Misalignment is an obvious issue since the monitoring networks for the two contaminants only partly intersect and because the collection rate for PM(2.5) is typically less frequent than that for ozone.Extending previous work in Berrocal et al. (2009), we introduce a bivariate downscaler that provides a flexible class of bivariate space-time assimilation models. We discuss computational issues for model fitting and analyze a dataset for ozone and PM(2.5) for the ozone season during year 2002. We show a modest improvement in predictive performance, not surprising in a setting where we can anticipate only a small gain.     

我国农村区域间收入差距构成的实证分析

 摘　　要:本文针对我国改革开放以来，农村东、中、西部三大区域间及其内部各省际间收入差距变动趋势进行分析，首先运用泰尔指数，探究到三大区域之间农民收入差距是我国农民收入差距拉大的主要原因；其次借助基尼系数，层次地挖掘到农民收入差距的拉大根源于工资性收入及农村产业结构的变革；再次通过横向比较，进一步揭示出工资性收入是缩小三大区域内部、拉大三大区域之间农民收入差距的关键所在；最后针对现存问题，提出了对策建议，以期为我国经济的增长、社会的和谐与稳定持续发展献计献策。     

Multimodal exponential families of circular distributions with application to daily peak hours of PM2.5 level in a large city

In this paper, we propose two multimodal circular distributions which are suitable for modeling circular data sets with two or more modes. Both distributions belong to the regular exponential family of distributions and are considered as extensions of the von Mises distribution. Hence, they possess the highly desirable properties, such as the existence of non-trivial sufficient statistics and optimal inferences for their parameters. Fine particulates (PM2.5) are generally emitted from activities such as industrial and residential combustion and from vehicle exhaust. We illustrate the utility of our proposed models using a real data set consisting of fine particulates (PM2.5) pollutant levels in Houston region during Fall season in 2019. Our results provide a strong evidence that its diurnal pattern exhibits four modes; two peaks during morning and evening rush hours and two peaks in between.     

异质型人力资本与经济发展——基于空间异质性的实证研究

区域经济发展的不平衡性,始终是社会经济研究领域内的热点问题。不同层级的人力资本,应与区域的异质性相一致,以实现各自区域经济发展的最大化。本文在充分考量“四大板块”区域异质性基础上,以人力资本的异质性为视角,利用1987-2017年的省级面板数据构建多种空间面板计量模型,从经济增长和经济运行质量两个维度来探寻不同层次人力资本对区域经济发展效能的空间差异。研究表明：①全国层面,所有层次的人力资本对经济增长均有促进作用;但初级和中级人力资本会遏制产业结构高级化,只有高级人力资本才能推动产业结构高级化。②区域层面,不同层次的人力资本对东、中、西和东北地区经济发展的直接效应和间接效应具有明显的区域空间异质性。     

中国快递业发展的区域不平衡性测度研究

选取大陆31个省份2007—2014年样本数据,分别测算三区域、八区域分组下快递业发展的不平衡性及极化趋势。研究结果表明:中国快递业发展存在较强的区域不平衡性,且这种不平衡性还呈现不断加大趋势;东中西快递业发展不平衡性明显,总体呈现东部强中西部弱的特点,基尼系数分解结果显示,东中西组间差异为不平衡性贡献了70%以上的份额,同时东部和西部地区内部也存在相当程度的不平衡性;八区域不平衡性也非常明显,总体呈现沿海强内陆弱、东强西弱、南强北弱的基本格局,组间差异贡献了88%左右的份额,就区域内而言,南部沿海和西北地区不平衡性较强,东部沿海、长江中游及东北地区则较为平衡;三区域及八区域分组下快递业不平衡发展均呈现出不断增强的极化趋势。     

我国地区R&D资本存量测算：1978-2015年

2008年国民账户体系（System of National Accounts, SNA）拓展了固定资产的边界,研发（Research and Development, R&D）被视为一类新的固定资产,列入了知识产权产品。目前,官方统计并未给出中国各地区的R&D资本存量数据,现有文献也鲜有讨论2008年SNA框架下的相关测算。因此,本文依据2008年SNA和现有的统计资料,在合理估计1978年以来各地区的当期R&D投资的基础上,采用永续盘存法科学测算了1978-2015年各地区的R&D资本存量数据。结果显示：1978年以来,中国各地区R&D资本存量总体上呈快速上升趋势;各地区R&D资本存量年均增速与各地区GDP年均增速,具有正相关关系;中国的R&D资本存量主要由东部地区贡献,东部地区是中国研发创新的主要区域。     

要素匹配与中国投资效率空间差异性——基于双层嵌套型函数的分解研究

本文基于四要素双层嵌套的生产函数,利用1990-2016年全国层面及省际层面数据测算投资效率,并分析其空间结构特征及演变轨迹,检验投资效率匹配效应影响因素。研究发现：①1990-2016年我国整体投资效率呈下降趋势,资本-技能劳动匹配效应与整体投资效率走势趋同,快速累积的资本存量和不断升级的资本质量与短缺的技能劳动之间矛盾突出。②东中西部地区投资效率增长非一致性明显。东部地区资本相对投资效率明显高于中西部,但下降幅度大于中西部,中西部与东部地区之间差距缩小,其中匹配效应是区域间投资效率非平衡的主要成因。③若产业结构升级的技能劳动需求不能满足,将引发要素错配,不利于有效投资。房价与工资提升分别通过影响技能劳动供给和需求抑制要素匹配效率;教育和公路设施会对地区要素匹配产生积极影响,改善地区间投资效率非均衡性;地区投资效率存在显著正向空间相关性,毗邻地区的要素流动和经济发展相近地区的技术溢出均对投资效率产生积极的影响。     

Testing differentially methylated regions through functional principal component analysis

DNA methylation is an epigenetic modification that plays an important role in many biological processes and diseases. Several statistical methods have been proposed to test for DNA methylation differences between conditions at individual cytosine sites, followed by a post hoc aggregation procedure to explore regional differences. While there are benefits to analyzing CpGs individually, there are both biological and statistical reasons to test entire genomic regions for differential methylation. Variability in methylation levels measured by Next-Generation Sequencing (NGS) is often observed across CpG sites in a genomic region. Evaluating meaningful changes in regional level methylation profiles between conditions over noisy site-level measurements is often difficult to implement with parametric models. To overcome these limitations, this study develops a nonparametric approach to detect predefined differentially methylated regions (DMR) based on functional principal component analysis (FPCA). The performance of this approach is compared with two alternative methods (GIFT and M3D), using real and simulated data.KEYWORDS: Functional principal component, epigenetics, DNA methylation, next-generation sequencing     

An empirical Bayes approach to evaluation of results for a specific region in multiregional clinical trials

To accelerate the drug development process and shorten approval time, the design of multiregional clinical trials (MRCTs) incorporates subjects from many countries/regions around the world under the same protocol. After showing the overall efficacy of a drug in all global regions, one can also simultaneously evaluate the possibility of applying the overall trial results to all regions and subsequently support drug registration in each of them. In this paper, we focus on a specific region and establish a statistical criterion to assess the consistency between the specific region and overall results in an MRCT. More specifically, we treat each region in an MRCT as an independent clinical trial, and each perhaps has different treatment effect. We then construct the empirical prior information for the treatment effect for the specific region on the basis of all of the observed data from other regions. We will conclude similarity between the specific region and all regions if the posterior probability of deriving a positive treatment effect in the specific region is large, say 80%. Numerical examples illustrate applications of the proposed approach in different scenarios. Copyright © 2013 John Wiley & Sons, Ltd.     

金融市场化对地区发展不平衡异质性影响研究

基于中心-外围模型思想及人口加权变异系数,本文对地区发展不平衡进行了测算及空间分解,而后实证检验了金融市场化对地区发展不平衡的异质性影响。主要研究结论如下：（1）金融市场化对中心区域和外围区域组内与组间发展不平衡的影响是异质性的;（2）金融市场化提升了东部地区总的发展不平衡,却降低了中西部地区总的发展不平衡,类似结果对于空间分解得到的其他发展不平衡指标也成立。     

公共压力、企业国际化与企业环境治理

企业环境行为和环境治理责任是社会各界普遍关注的重要话题。本文借助2011年年底的PM2.5爆表事件作为外生冲击,系统地考察了PM2.5爆表事件后企业国际化对环境治理行为的影响机理和作用机制。实证检验发现：第一,在PM2.5爆表事件后,相比于国际化程度低的企业,国际化程度高的企业环境治理绩效更好,表现为企业环境资本投资更多;第二,PM2.5爆表事件带来的公共压力对国际化程度高的企业环境治理的提升现象在信息透明度低、分析师跟踪少的企业更加显著;第三,在民营性质、高管理层权力及行业竞争程度高的企业中,PM2.5爆表事件带来的公共压力对国际化程度高的企业环境治理的提升现象更为明显。     

Spatial modeling of extreme rainfall in northeast Thailand

It is well recognized that the generalized extreme value (GEV) distribution is widely used for any extreme events. This notion is based on the study of discrete choice behavior; however, there is a limit for predicting the distribution at ungauged sites. Hence, there have been studies on spatial dependence within extreme events in continuous space using recorded observations. We model the annual maximum daily rainfall data consisting of 25 locations for the period from 1982 to 2013. The spatial GEV model that is established under observations is assumed to be mutually independent because there is no spatial dependency between the stations. Furthermore, we divide the region into two regions for a better model fit and identify the best model for each region. We show that the regional spatial GEV model reflects the spatial pattern well compared with the spatial GEV model over the entire region as the local GEV distribution. The advantage of spatial extreme modeling is that more robust return levels and some indices of extreme rainfall can be obtained for observed stations as well as for locations without observed data. Thus, the model helps to determine the effects and assessment of vulnerability due to heavy rainfall in northeast Thailand.     

Accuracy of edge detection methods with local information in speckled imagery

We compare the accuracy of five approaches for contour detection in speckled imagery. Some of these methods take advantage of the statistical properties of speckled data, and all of them employ active contours using B-spline curves. Images obtained with coherent illumination are affected by a noise called speckle, which is inherent to the imaging process. These data have been statistically modeled by a multiplicative model using the G0 distribution, under which regions with different degrees of roughness can be characterized by the value of a parameter. We use this information to find boundaries between regions with different textures. We propose and compare five strategies for boundary detection: three based on the data (maximum discontinuity on raw data, fractal dimension and maximum likelihood) and two based on estimates of the roughness parameter (maximum discontinuity and anisotropic smoothed roughness estimates). In order to compare these strategies, a Monte Carlo experience was performed to assess the accuracy of fitting a curve to a region. The probability of finding the correct edge with less than a specified error is estimated and used to compare the techniques. The two best procedures are then compared in terms of their computational cost and, finally, we show that the maximum likelihood approach on the raw data using the G0 law is the best technique.     

金融发展差异与货币政策区域效应——以华东六省一市为例

选取华东六省一市作为研究对象,运用因子分析方法研究2012年该7个省市金融发展情况及其差异,并对其金融发展相似性进行聚类分析。在此基础上,采用1990—2012年数据,对聚类后的三类地区通过基于VAR模型的协整关系检验、Granger因果关系检验等建立变量间长期均衡模型,实证研究货币政策在华东地区不同省市效应的差异性。研究结果表明:三类地区经济增长和货币政策对于区域金融发展均具有明显的区域效应,经济发展和广义货币供应量与金融发展均呈正相关关系。鉴此,提出如下政策建议:正视区域经济发展差异,实施差别化货币调控政策;优化各区域金融结构差异,改善货币政策传导效应等。     

中国地区经济发展不平衡及影响因素研究——基于夜间灯光数据

本文以全球夜间灯光数据为参照，分别从地级和县级行政区层面研究了1992-2016年我国地区经济发展不平衡的演化及其影响因素。受地级和县级人均GDP数据可得性和准确性的限制，首先利用省级人均GDP与灯光亮度关系估算地级和县级的经济产出水平。基于地级和县级经济产出水平，测算了地区经济差异指数、泰尔指数和阿特金森指数，证实了各省份、全国及四大地区均呈现库兹涅茨倒“U”曲线。对泰尔指数进行四大地区分解，发现了四大地区间的经济差异是我国地区经济不平衡的主要根源。地区经济发展不平衡的影响因素研究再次证实库兹涅茨曲线的存在，还发现城镇化水平和产业结构变迁与地区经济不平衡之间也存在倒“U”型关系，教育水平的提升与交通基础设施的完善分别扩大和缩小了地区经济的不平衡，但资源禀赋、对外开放度和政府消费与地区经济不平衡的关系并不显著。     

西部承接东部地区产业转移的实证分析——以陕西省为例

欠发达地区积极主动地承接发达地区的产业转移,已成为其加快经济发展的重要途径.采用区域产业静态和动态集聚指数测算出东部地区五省一市具有转移趋势的产业和陕西省的区位优势产业,在此基础上确定出陕西省承接东部地区产业转移的对接行业.结果表明,东部五省一市目前劳动密集型产业对外转移趋势明显,陕西省的优势产业主要是重工业及资源型工业.陕西省应利用自己的产业基础和优势,找准产业承接的行业对接点.     

Regional efficacy evaluation in multi-regional clinical trials using a discounting factor weighted Z test

Multi-regional clinical trial (MRCT) is an efficient design to accelerate drug approval globally. Once the global efficacy of test drug is demonstrated, each local regulatory agency is required to prove effectiveness of test drug in their own population. Meanwhile, the ICH E5/E17 guideline recommends using data from other regions to help evaluate regional drug efficacy. However, one of the most challenges is how to manage to bridge data among multiple regions in an MRCT since various intrinsic and extrinsic factors exist among the participating regions. Furthermore, it is critical for a local agency to determine the proportion of information borrowing from other regions given the ethnic differences between target region and non-target regions. To address these issues, we propose a discounting factor weighted Z statistic to adaptively borrow information from non-target regions. In this weighted Z statistic, the weight is derived from a discounting factor in which the discounting factor denotes the proportion of information borrowing from non-target regions. We consider three ways to construct discounting factors based on the degree of congruency between target and non-target regions either using control group data, or treatment group data, or all data. We use the calibrated power prior to construct discounting factor based on scaled Kolmogorov–Smirnov statistic. Comprehensive simulation studies show that our method has desirable operating characteristics. Two examples are used to illustrate the applications of our proposed approach.     

劳动力流动对中国地区经济差距影响的空间计量经济模型分析

学术界对劳动力流动对地区经济发展产生的影响有两种不同观点：一种观点认为劳动力流动能够缩小地区差距;另一种观点则认为劳动力流动会扩大地区发展差距。考虑各地区经济发展的空间依赖性,通过构建空间计量经济模型,并利用中国各省区经济的面板数据进行研究与实证分析。结果表明：劳动力流动对中国不同地区经济发展的作用方向和强度表现不同,对地区差距的影响是劳动力流入与劳动力流出综合作用产生的结果。     

中国区域经济协调发展实证研究

 由于我国经济发展的区域不均衡性,区域经济的协调发展问题不仅是我国一项长期重要国策,也使其成为社会经济研究的热点问题。本文将空间计量模型与面板分析方法相结合,以我国省域经济发展作为研究对象和数据来源,从而对我国省域经济增长的协调发展和所受影响因素进行研究。结果显示,我国区域经济发展存在着显著的空间相关性,在经济发展的不同阶段影响经济增长的因素不同,对经济发展有持续显著正影响的因素有：人力资本、人口资本、市场化进程和财政支出等。据此本文提出若干政策建议,以促进我国经济协调增长。     

基于SFA我国区域全要素生产率差异的实证研究

本文利用SFA对我国区域全要素生产率进行实证研究之后认为：改革开放以来我国不同地区的全要素生产率均有明显上升,但欠发达地区的增长快于发达地区,说明TFP有一定的收敛性;而从TFP增长率的构成看,技术进步的贡献最大,规模经济贡献很小,生产效率的贡献甚至为负值,说明我国在以往的经济增长中,注重了技术进步,而忽略了地区生产效率的提高。