An approximation to the convolution of gamma distributions

In general, the exact distribution of a convolution of independent gamma random variables is quite complicated and does not admit a closed form. Of all the distributions proposed, the gamma-series representation of Moschopoulos (1985 Moschopoulos, P. G. (1985). The distribution of the sum of independent gamma random variables. Annals of the Institute of Statistical Mathematics 37Part A:541–544. [Google Scholar]) is relatively simple to implement but for particular combinations of scale and/or shape parameters the computation of the weights of the series can result in complications with too much time consuming to allow a large-scale application. Recently, a compact random parameter representation of the convolution has been proposed by Vellaisamy and Upadhye (2009 Vellaisamy, P., Upadhye, N. S. (2009). On the sums of compound negative binomial and gamma random variables. Journal of Applied Probability 46:272–283.[Crossref], [Web of Science ®] , [Google Scholar]) and it allows to give an exact interpretation to the weights of the series. They describe an infinite discrete probability distribution. This result suggested to approximate Moschopoulos’s expression looking for an approximating theoretical discrete distribution for the weights of the series. More precisely, we propose a general negative binomial distribution. The result is an “excellent” approximation, fast and simple to implement for any parameter combination.     

A new generalized two-sided class of distributions with an emphasis on two-sided generalized normal distribution

The ordinary-G class of distributions is defined to have the cumulative distribution function (cdf) as the value of the cdf of the ordinary distribution F whose range is the unit interval at G, that is, F(G), and it generalizes the ordinary distribution. In this work, we consider the standard two-sided power distribution to define other classes like the beta-G and the Kumaraswamy-G classes. We extend the idea of two-sidedness to other ordinary distributions like normal. After studying the basic properties of the new class in general setting, we consider the two-sided generalized normal distribution with maximum likelihood estimation procedure.     

A new generalization of the Weibull-geometric distribution with bathtub failure rate

In this paper, the researchers attempt to introduce a new generalization of the Weibull-geometric distribution. The failure rate function of the new model is found to be increasing, decreasing, upside-down bathtub, and bathtub-shaped. The researchers obtained the new model by compounding Weibull distribution and discrete generalized exponential distribution of a second type, which is a generalization of the geometric distribution. The new introduced model contains some previously known lifetime distributions as well as a new one. Some basic distributional properties and moments of the new model are discussed. Estimation of the parameters is illustrated and the model with two known real data sets is examined.     

一般信任模式的跨部门差异及其中介机制: 基于2010年中国综合社会调查的研究

本文基于“市场”与“国家再分配”两种不同制度环境的讨论,利用中国综合社会调查2010年的数据,运用倾向值匹配方法处理潜在的选择性误差,考察了不同部门中个体的一般信任水平。结果显示,相比私有部门（外资企业和私营企业）,在公共部门中工作的个体呈现了更高的一般信任水平。进一步的分析表明,政治参与水平和相对剥夺感作为中介于工作部门与一般信任水平之间的解释机制是显著的,在公共部门中工作的个体不仅在态度上对内在政治效能感有更高的认定,而且也能积极参与居委会社区的选举。这些特征极大提升了他们的一般信任水平。此外,公共部门中的个体在社会地位与经济地位上所持有的较低的相对剥夺感也有助于其建立更高的一般信任水平。     

我国经济欠发达地区农村社会养老保险制度的构建

与发达地区相比,我国经济欠发达地区农村养老保险发展十分缓慢,覆盖面极其有限。实际上,经济欠发达地区的农民最需要社会养老保险,因为他们的基本生活需求没有保证,这些地区未富先老特征更为明显,传统的保障功能在弱化。然而,源于农民收入低,增长慢,支付保险费的能力弱;集体经济薄弱,无法为农民养老保险提供资金支持;地方财力单薄,难以全面提供以政府为主的养老基金融资;经济欠发达地区农民获得社会养老保险能力又最弱。为此,应将经济欠发达地区农村社会养老保险作为建设覆盖城乡居民社会保障体系的推进重点,变政府扶持为财政拨款,并向经济欠发达地区倾斜;大力进行宣传教育,让农民充分了解参加社会养老保险的必要性。     

Rényi entropy of m-generalized order statistics

Abstract

Characterizing relations via Rényi entropy of m-generalized order statistics are considered along with examples and related stochastic orderings. Previous results for common order statistics are included.     

科学元原则的动摇与后科学时代

科学是按“元原则→公理体系→数学与逻辑方法→具体科学→具体科学技术、工程等的应用”的程式完成其建构的。通过对这一程式的静态分析,可发现科学本身的真理性（即科学性）是值得怀疑的;科学一元论的统治也是值得怀疑的。这种怀疑,使我们看到了后科学时代的曙光。