中国碳排放的环境库兹涅茨曲线分析——基于空间面板模型的实证研究

在环境库兹涅茨曲线理论的基础上,选用30个省域2000—2009年数据,运用空间面板计量经济模型研究碳排放与经济增长的关系,结果表明:利用空间相关性指标检验出经济发展与碳排放之间存在显著的空间效应;利用空间面板自回归和误差模型发现,中国碳排放与经济增长存在倒U形关系,转折点在8.167亿元至11.025亿元人均GDP之间;工业结构比重对碳减排有消极影响,而技术进步、FDI与碳排放之间存在显著的正效应,这说明通过降低工业结构比重、促进新能源技术的革新以及引进外资等能减少中国的碳排放。     

非参数固定效应Panel Data模型的分位数回归推断

利用分位数回归方法,讨论了非参数固定效应Panel Data模型的估计和检验问题,得到了参数估计的渐近正态性及收敛速度。同时,建立一个秩得分(rank score)统计量来检验模型的固定效应,并证明了这个统计量渐近服从标准正态分布。     

基于数据汇总的普查调查框误差研究

作为一种全面调查,普查数据的生产过程可以视为由个体数据汇总为总量数据的过程.为了开展普查数据质量评估与控制研究,从中国普查调查实施过程共性出发,构建普查数据汇总模型的一般形式,并以此为基础界定普查调查框及其作用,将普查划分为两种类型;同时从普查数据汇总的角度论述普查调查框误差的量化形式,进一步完善单位清查(清查摸底)环节在普查数据汇总中的理论意义.     

On pooling data summaries in the absence of interactions “response-by-study”

The standard hypothesis testing procedure in meta-analysis (or multi-center clinical trials) in the absence of treatment-by-center interaction relies on approximating the null distribution of the standard test statistic by a standard normal distribution. For relatively small sample sizes, the standard procedure has been shown by various authors to have poor control of the type I error probability, leading to too many liberal decisions. In this article, two test procedures are proposed, which rely on thet—distribution as the reference distribution. A simulation study indicates that the proposed procedures attain significance levels closer to the nominal level compared with the standard procedure.     

Choice of Parametric Accelerated Life and Proportional Hazards Models for Survival Data: Asymptotic Results

We discuss the impact of misspecifying fully parametric proportional hazards and accelerated life models. For the uncensored case, misspecified accelerated life models give asymptotically unbiased estimates of covariate effect, but the shape and scale parameters depend on the misspecification. The covariate, shape and scale parameters differ in the censored case. Parametric proportional hazards models do not have a sound justification for general use: estimates from misspecified models can be very biased, and misleading results for the shape of the hazard function can arise. Misspecified survival functions are more biased at the extremes than the centre. Asymptotic and first order results are compared. If a model is misspecified, the size of Wald tests will be underestimated. Use of the sandwich estimator of standard error gives tests of the correct size, but misspecification leads to a loss of power. Accelerated life models are more robust to misspecification because of their log-linear form. In preliminary data analysis, practitioners should investigate proportional hazards and accelerated life models; software is readily available for several such models.     

Conditions for Non-confounding and Collapsibility without Knowledge of Completely Constructed Causal Diagrams

In this paper, we discuss several concepts in causal inference in terms of causal diagrams proposed by Pearl (1993 , 1995a , b ), and we give conditions for non-confounding, homogeneity and collapsibility for causal effects without knowledge of a completely constructed causal diagram. We first introduce the concepts of non-confounding, conditional non-confounding, uniform non-confounding, homogeneity, collapsibility and strong collapsibility for causal effects, then we present necessary and sufficient conditions for uniform non-confounding, homegeneity and collapsibilities, and finally we show sufficient conditions for non-confounding, conditional non-confounding and uniform non-confounding.     

Bayesian modelling of catch in a north-west Atlantic fishery

Summary. We model daily catches of fishing boats in the Grand Bank fishing grounds. We use data on catches per species for a number of vessels collected by the European Union in the context of the Northwest Atlantic Fisheries Organization. Many variables can be thought to influence the amount caught: a number of ship characteristics (such as the size of the ship, the fishing technique used and the mesh size of the nets) are obvious candidates, but one can also consider the season or the actual location of the catch. Our database leads to 28 possible regressors (arising from six continuous variables and four categorical variables, whose 22 levels are treated separately), resulting in a set of 177 million possible linear regression models for the log-catch. Zero observations are modelled separately through a probit model. Inference is based on Bayesian model averaging, using a Markov chain Monte Carlo approach. Particular attention is paid to the prediction of catches for single and aggregated ships.     

Bayes model averaging with selection of regressors

Summary. When a number of distinct models contend for use in prediction, the choice of a single model can offer rather unstable predictions. In regression, stochastic search variable selection with Bayesian model averaging offers a cure for this robustness issue but at the expense of requiring very many predictors. Here we look at Bayes model averaging incorporating variable selection for prediction. This offers similar mean-square errors of prediction but with a vastly reduced predictor space. This can greatly aid the interpretation of the model. It also reduces the cost if measured variables have costs. The development here uses decision theory in the context of the multivariate general linear model. In passing, this reduced predictor space Bayes model averaging is contrasted with single-model approximations. A fast algorithm for updating regressions in the Markov chain Monte Carlo searches for posterior inference is developed, allowing many more variables than observations to be contemplated. We discuss the merits of absolute rather than proportionate shrinkage in regression, especially when there are more variables than observations. The methodology is illustrated on a set of spectroscopic data used for measuring the amounts of different sugars in an aqueous solution.     

QFII对证券市场行业收益波动率影响研究

该文选取QFII进入我国A股市场后全阶段重仓持股的六大行业2002年7月1日至2008年7月31日之间的日收盘价,以研究QFII对六大行业波动收益率的影响。GARCH(1,1)模型和EGARCH(1,1)模型检验结果显示,在QFII刚进入时,QFII投资没有引起行业收益波动率的增加。分析结果显示,即使在2005年第四季度股改开始后,除金属、非金属和金融保险业外,QFII投资没有引起行业波动率增加,而在2007年12月QFII批准投资额度增加后,行业收益波动率增加。     

中国城市化发展进程及展望

中国的城市化在改革开放后步入了平稳发展期,遵循城市化逻辑增长模型,利用1973-2008年的数据进行估计后得出:中国城市化年均增长速度为0.0412,远远快于0.01729的世界平均水平;2014年左右,中国将结束高速城市化过程,此时的城市化率将达50.11%;中国城市化的饱和值约为84.98%,而67%左右可能是中国未来20年城市化发展的顶部,此后城市化水平会在一个较长的时期维持在70%左右。