A longitudinal analysis of infant and senescent mortality using mixture models

We construct a mixture distribution including infant, exogenous and Gompertzian/non-Gompertzian senescent mortality. Using mortality data from Swedish females 1751–, we show that this outperforms models without these features, and compare its trends in cohort and period mortality over time. We find an almost complete disappearance of exogenous mortality within the last century of period mortality, with cohort mortality approaching the same limits. Both Gompertzian and non-Gompertzian senescent mortality are consistently present, with the estimated balance between them oscillating constantly. While the parameters of the latter appear to be trending over time, the parameters of the former do not.     

On a bounded bimodal two-sided distribution fitted to the Old-Faithful geyser data

In this paper, we shall develop a novel family of bimodal univariate distributions (also allowing for unimodal shapes) and demonstrate its use utilizing the well-known and almost classical data set involving durations and waiting times of eruptions of the Old-Faithful geyser in Yellowstone park. Specifically, we shall analyze the Old-Faithful data set with 272 data points provided in Dekking et al. [3]. In the process, we develop a bivariate distribution using a copula technique and compare its fit to a mixture of bivariate normal distributions also fitted to the same bivariate data set. We believe the fit-analysis and comparison is primarily illustrative from an educational perspective for distribution theory modelers, since in the process a variety of statistical techniques are demonstrated. We do not claim one model as preferred over the other.     

中国居民收入分布专题实证研究——居民收入分布变迁测度及其影响因素分解

基于核密度估计方法,给出居民收入分布变迁测度及其影响因素分解的相对收入分布方法。使用中国健康和营养调查的微观居民收入数据,实证分析中国居民收入分布及其变迁的特征、过程及其影响因素。实证结果显示:中国居民收入分布变迁的速度与经济体制改革进程相对应;经济增长因素是引起居民收入分布变迁的主要因素,在提高总体居民收入水平的同时加剧了居民收入分布的极化程度;收入分配因素对居民收入分布变迁的作用相对较弱,但有一定的减贫或缩小居民收入差距作用。     

关于层次分析法的数值试验

通过对层次分析法进行数值模拟,证实了次序性程度不仅对评价结果存在着显著的影响,而且也与一致性指标存在着密切的关系,同时也证实了标度精度不足是导致多种标度并存的原因,并建议采用适当的标度精度,这一观点与Saaty是一致的。实验结果还清楚地表明,单纯使用一致性指标判定一个矩阵好坏是不够的,应该辅助以其它指标。     

关系化用工:农业规模经营的社会基础

农业规模经营是中国乡村振兴进程中的关键议题。农业规模经营在快速发展的同时也呈现出用工效益的差异,从而使一些规模农业经营主体陷入困境。采用嵌入性视角探讨农业规模经营中用工模式嵌入社会关系的逻辑及其影响。研究发现,农业规模经营陷入困境的主要原因在于市场化用工无法有效解决农业规模经营中的劳动监督问题。而将市场规则嵌入关系规则的关系化用工使得雇佣双方产生了利他倾向,进而在很大程度上调动了工人内在的劳动积极性,从而使农业规模经营主体摆脱经营失败困境。关系化用工的实现依赖于农业规模经营主体在用工选择、生产管理和日常生活中充分发挥社会关系的积极作用,但社会关系范围和程度都是有限度的。因此,农业规模经营的健康发展不仅需要处理好经济关系,而且需要处理好社会关系。     

Extended generalised Pareto models for tail estimation

The most popular approach in extreme value statistics is the modelling of threshold exceedances using the asymptotically motivated generalised Pareto distribution. This approach involves the selection of a high threshold above which the model fits the data well. Sometimes, few observations of a measurement process might be recorded in applications and so selecting a high quantile of the sample as the threshold leads to almost no exceedances. In this paper we propose extensions of the generalised Pareto distribution that incorporate an additional shape parameter while keeping the tail behaviour unaffected. The inclusion of this parameter offers additional structure for the main body of the distribution, improves the stability of the modified scale, tail index and return level estimates to threshold choice and allows a lower threshold to be selected. We illustrate the benefits of the proposed models with a simulation study and two case studies.     

公平分配与居民福利——收入差距对中国居民恩格尔系数的影响分析

居民收入水平不同,恩格尔系数也不同,因此收入分配对社会总体恩格尔系数的影响是不确定的。基于马斯洛层次需求理论证明边际食品消费倾向递减,并且当消费函数为线性或近似线性时,收入差距扩大会降低恩格尔系数。基于省际面板数据的实证分析表明,中国居民边际食品消费倾向递减且消费函数为(近似)线性,居民收入差距扩大降低了居民恩格尔系数(基尼系数升高对恩格尔系数下降的贡献率为22%),从而出现"分配越不平等,居民总体生活水平越高"的矛盾现象。因此在使用总体指标评价居民生活水平时,收入分配指标必须得到同等的重视;在经济发展中,公平和效率必须兼顾才能实现居民福利最大化。     

An Improved Boxplot for Univariate Data

The boxplot is an effective data-visualization tool useful in diverse applications and disciplines. Although more sophisticated graphical methods exist, the boxplot remains relevant due to its simplicity, interpretability, and usefulness, even in the age of big data. This article highlights the origins and developments of the boxplot that is now widely viewed as an industry standard as well as its inherent limitations when dealing with data from skewed distributions, particularly when detecting outliers. The proposed Ratio-Skewed boxplot is shown to be practical and suitable for outlier labeling across several parametric distributions.     

Generation of multivariate distributions by vertical density representation

Troutt (1991,1993) proposed the idea of the vertical density representation (VDR) based on Box-Millar method. Kotz, Fang and Liang (1997) provided a systematic study on the multivariate vertical density representation (MVDR). Suppose that we want to generate a random vector X[d]Rⁿthat has a density function ?(x). The key point of using the MVDR is to generate the uniform distribution on [D]_?(v) = {x :?(x) = v} for any v > 0 which is the surface in RⁿIn this paper we use the conditional distribution method to generate the uniform distribution on a domain or on some surface and based on it we proposed an alternative version of the MVDR(type 2 MVDR), by which one can transfer the problem of generating a random vector X with given density f to one of generating (X, X_n+i) that follows the uniform distribution on a region in Rⁿ⁺¹defined by ?. Several examples indicate that the proposed method is quite practical.