Bayesian quantile regression for skew-normal linear mixed models

Linear mixed models have been widely used to analyze repeated measures data which arise in many studies. In most applications, it is assumed that both the random effects and the within-subjects errors are normally distributed. This can be extremely restrictive, obscuring important features of within-and among-subject variations. Here, quantile regression in the Bayesian framework for the linear mixed models is described to carry out the robust inferences. We also relax the normality assumption for the random effects by using a multivariate skew-normal distribution, which includes the normal ones as a special case and provides robust estimation in the linear mixed models. For posterior inference, we propose a Gibbs sampling algorithm based on a mixture representation of the asymmetric Laplace distribution and multivariate skew-normal distribution. The procedures are demonstrated by both simulated and real data examples.     

人口受教育程度对居民消费的影响研究--基于动态面板分位数回归法

本文采用1996～2015年的31个省市自治区宏观数据,使用动态面板分位数回归方法研究人口受教育程度和居民消费的数量关系。研究结果表明,人口受教育程度对消费有着较为显著的影响,且人口受教育程度对中等消费支出水平的影响略大于高、低消费支出水平的影响,这说明中等消费水平的居民消费受到人口受教育程度的影响更加敏感和有弹性。另外,模型中其他各解释变量系数在各分位数上的差异不大,说明这些影响因素对于不同消费支出水平的消费影响没有太明显差异。     

一类带耗散项非线性波动问题的研究

对一类带耗散项非线性波动方程进行了研究,用“参数微分法”,得到其解析近似解。其结果可用于研讨摄动对原物理问题的解的影响,类似的问题在许多动力学问题物理解的数值定性分析及应用WKB方处理时也会常遇到。     

股指期货最优套期保值与绩效评价——基于分位数回归的实证研究

针对股指期货套期保值的问题,利用分位数回归方法对沪深300指数中权重占前两位的股票的最优套期保值比率进行了实证测算和绩效评价,实证结果表明：运用分位数回归计算得到的最优套期保值比率都大于0.99,在不同分位点上,期货收益对现货收益的影响大小及变动情况存在明显差异。     

中国农村贫困人口多维特征分析

利用中国综合社会调查（CGSS）数据,从个体的基本特征、家庭特征、社会特征和其他特征4个维度,采用二值Logit模型,考察这些特征变量对于农村人口陷入贫困可能性的影响;并进一步通过分位数回归模型比较分析这些特征变量对农村贫困人口和非贫困人口不同收入水平的影响。研究发现,在中国农村,具有以下几个典型特征的人群陷入贫困的可能性较大：老年人、受教育程度较低（自身、配偶或父母）、身体健康状况较差、少数民族、未婚状态、家庭抚养负担过重、无宗教信仰、没有非农工作、周工作时间较短、使用电视或互联网频率较低（这里理解为获取与农业生产和非农就业相关信息）。此外,比较分析结果表明,对于贫困人口和非贫困人口,不同维度下特征变量对收入水平影响的大小和方向存在较大差异。     

Confidence and prediction intervals based on interpolated records

In several statistical problems, nonparametric confidence intervals for population quantiles can be constructed and their coverage probabilities can be computed exactly, but cannot in general be rendered equal to a pre-determined level. The same difficulty arises for coverage probabilities of nonparametric prediction intervals for future observations. One solution to this difficulty is to interpolate between intervals which have the closest coverage probability from above and below to the pre-determined level. In this paper, confidence intervals for population quantiles are constructed based on interpolated upper and lower records. Subsequently, prediction intervals are obtained for future upper records based on interpolated upper records. Additionally, we derive upper bounds for the coverage error of these confidence and prediction intervals. Finally, our results are applied to some real data sets. Also, a comparison via a simulation study is done with similar classical intervals obtained before.     

An empirical investigation of the box-cox model and a nonlinear least squares alternative

In this paper we present a generalized functional form estimator, recently developed by jeffrey Wooldridge; and then we compare it empirically to the popular Box-Cox (BC) estimator using three data sets. We begin by briefly reviewing the drawbacks of the BC estimator. We Then introduce the nonlinear lest squares (NLS) alternative of Wooldridge which retains the desirable qualities of the BC estimator without the associated theoretical problems. We continue by applying both the BC and the NLS models to data from three classic hedonic regression studies and then compare the estimation resuts-point estimates, inferences and fitted values. The estimations include a wage rate equation, and two computer hedonic regression equations, one using data from a classic study by Gregory Chow and the other using an IBM data set that formed the basis of the new official BLS computer price index.     

An Empirical Comparison of Estimating Methods for the Ramberg–Osgood EIV Model

The standard tensile test is one of the most frequent tools performed for the evaluation of mechanical properties of metals. An empirical model proposed by Ramberg and Osgood fits the tensile test data using a nonlinear model for the strain in terms of the stress. It is an Error-In-Variables (EIV) model because of the uncertainty affecting both strain and stress measurement instruments. The SIMEX, a simulation-based method for the estimation of model parameters, is powerful in order to reduce bias due to the measurement error in EIV models. The plan of this article is the following. In Sec. 2, we introduce the Ramberg–Osgood model and another reparametrization according to different assumptions on the independent variable. In Sec. 3, there is a summary of SIMEX method for the case at hand. Section 4 is a comparison between SIMEX and others estimating methods in order to highlight the peculiarities of the different approaches. In the last section, there are some concluding remarks.     

欧洲主权债务危机与欧元的前景

由美国次贷危机引发的全球性金融危机对欧洲大陆的冲击使欧洲长期积累的财政和债务问题逐步转变为主权债务危机。欧债危机的持续发酵主要是由欧元区内货币政策与财政政策脱节、高社会福利与低经济增长矛盾以及危机爆发后救助迟缓、乏力等因素导致的,同时它也是欧元区在建立之初就一直存在的严重的结构性缺陷所带来危害的集中体现。欧债危机对欧元区的稳定造成了极大冲击,给欧元未来的命运蒙上了一层阴影。欧元区未来的结局可能是促使欧债危机国家退出欧元区,而这对欧洲一体化进程则是沉重的打击。