Hazard functions and life distributions in discrete time

The problem of studying lifelength distributions in discrete time is considered for certain forms of hazard functions. A class of life distributions that consists of the geometric, the Waring and the negative hypergeometric distributions is shown to result when the hazard function is inversely proportional to some linear function of time.     

The beta generalized linear exponential distribution

In this paper, a new five-parameter lifetime distribution called beta generalized linear exponential distribution (BGLED) is introduced. It includes at least 17 popular sub-models as special cases such as the beta linear exponential, the beta generalized exponential, and the exponentiated generalized linear distributions. Mathematical and statistical properties of the proposed distribution are discussed in details. In particular, explicit expression for the density function, moments, asymptotics distributions for sample extreme statistics, and other statistical measures are obtained. The estimation of the parameters by the method of maximum-likelihood is discussed and the finite sample properties of the maximum-likelihood estimators (MLEs) are investigated numerically. A real data set is used to demonstrate its superior performance fit over several existing popular lifetime models.     

On additive-multiplicative hazards model

In survival analysis and reliability theory, a fundamental problem is the study of lifetime properties of a live organism or system. In this regard, there have been considered and studied several models based on different concepts of ageing such as hazard rate and mean residual life. In this paper, we consider an additive-multiplicative hazard model (AMHM) and study some reliability and ageing properties of the proposed model. We then specify the bivariate models whose conditionals satisfy AMHM. Several properties of the proposed bivariate model are investigated and adequacy of the model is evaluated based on a real data set.     

An Additive–Multiplicative Restricted Mean Residual Life Model

The mean residual life measures the expected remaining life of a subject who has survived up to a particular time. When survival time distribution is highly skewed or heavy tailed, the restricted mean residual life must be considered. In this paper, we propose an additive–multiplicative restricted mean residual life model to study the association between the restricted mean residual life function and potential regression covariates in the presence of right censoring. This model extends the proportional mean residual life model using an additive model as its covariate dependent baseline. For the suggested model, some covariate effects are allowed to be time‐varying. To estimate the model parameters, martingale estimating equations are developed, and the large sample properties of the resulting estimators are established. In addition, to assess the adequacy of the model, we investigate a goodness of fit test that is asymptotically justified. The proposed methodology is evaluated via simulation studies and further applied to a kidney cancer data set collected from a clinical trial.     

Survival and lifetime data analysis with a flexible class of distributions

We introduce a general class of continuous univariate distributions with positive support obtained by transforming the class of two-piece distributions. We show that this class of distributions is very flexible, easy to implement, and contains members that can capture different tail behaviours and shapes, producing also a variety of hazard functions. The proposed distributions represent a flexible alternative to the classical choices such as the log-normal, Gamma, and Weibull distributions. We investigate empirically the inferential properties of the proposed models through an extensive simulation study. We present some applications using real data in the contexts of time-to-event and accelerated failure time models. In the second kind of applications, we explore the use of these models in the estimation of the distribution of the individual remaining life.     

Dynamic reliability models with conditional proportional hazards

A dynamic approach to the stochastic modelling of reliability systems is further explored. This modelling approach is particularly appropriate for load-sharing, software reliability, and multivariate failure-time models, where component failure characteristics are affected by their degree of use, amount of load, or extent of stresses experienced. This approach incorporates the intuitive notion that when a set of components in a coherent system fail at a certain time, there is a jump from one structure function to another which governs the residual lifetimes of the remaining functioning components, and since the component lifetimes are intrinsically affected by the structure function which they constitute, then at such a failure time there should also be a jump in the stochastic structure of the lifetimes of the remaining components. For such dynamically-modelled systems, the stochastic characteristics of their jump times are studied. These properties of the jump times allow us to obtain the properties of the lifetime of the system. In particular, for a Markov dynamic model, specific expressions for the exact distribution functions of the jump times are obtained for a general coherent system, a parallel system, and a series-parallel system. We derive a new family of distribution functions which describes the distributions of the jump times for a dynamically-modelled system.     

产业政策、融资能力与股权价值

产业政策是一种政府行为,是政府为了实现其经济和社会发展目标而制定的各种政策总和。本文基于Tirole （2006）的企业融资分析框架,分析了政府的投资补贴、收入税和预算平衡三种产业政策对企业家融资能力和股权价值的影响。理论研究表明：就股份制企业而言,投资补贴政策将增加企业家的融资能力及其股权价值,扩大投资规模,收入税政策则相反;预算平衡的产业政策对企业家的融资能力、股权价值及投资规模无影响。此外,在投资补贴和预算平衡这两种产业政策下,企业家的股权价值均大于1,且投资规模与其自有资产呈一种倍数关系。然而,在收入税政策下,企业家的股权价值则不一定大于1,投资规模也未必是其自有资产的倍数乘数。     

新型农村合作医疗中的道德风险及其规避——以湖南省隆回县为例

新型农村合作医疗中道德风险的产生有其内在机理,为有效规避新型农村合作医疗中的道德风险,应当建立信息批露与评价机制,缓减新型农村合作医疗中委托-代理双方的信息不对称问题;降低代理方道德风险行为的收益,弱化代理方道德风险行为的动力;健全监督机制,增大博弈成本,规范代理方的博弈行为;完善相应的配套措施。     

现代企业的融资安排与公司绩效的改善--兼论我国国有企业资本结构的重整战略

在现代企业理论中,企业的融资安排不再是仅涉及融资成本的问题,更重要的是它在公司治理中发挥了意想不到的作用,债权和股权两种不同性质的契约在约束经理人行为和解决代理问题上有着不同的约束力,甚至在某种程度上还可以互相补充.我国国有企业经营效益低下大部分是因为国有企业缺乏合理的融资结构,因而导致治理的低效率.所以,要提高企业效益就必须改革企业融资制度,让企业在自由的、市场化的融资条件下作出正确的融资决策.     

A unified approach to stochastic comparisons of multivariate mixture models

In this paper, we consider a unified approach to stochastic comparisons of random vectors corresponding to two general multivariate mixture models. These stochastic comparisons are made with respect to multivariate hazard rate, reversed hazard rate and likelihood ratio orders. As an application, results are presented for stochastic comparisons of generalized multivariate frailty models.