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91.
In biomedical studies, interest often focuses on the relationship between patients characteristics or some risk factors and both quality of life and survival time of subjects under study. In this paper, we propose a simultaneous modelling of both quality of life and survival time using the observed covariates. Moreover, random effects are introduced into the simultaneous models to account for dependence between quality of life and survival time due to unobserved factors. EM algorithms are used to derive the point estimates for the parameters in the proposed model and profile likelihood function is used to estimate their variances. The asymptotic properties are established for our proposed estimators. Finally, simulation studies are conducted to examine the finite-sample properties of the proposed estimators and a liver transplantation data set is analyzed to illustrate our approaches. 相似文献
92.
张进辅 《西南大学学报(社会科学版)》2006,32(3)
西南民族心理研究对于西南乃至整个国家的发展、民族和谐和社会稳定具有十分重要和特殊的意义.总体而言,在研究目标上要进一步强化为社会发展与稳定、为建立和谐社会服务的功能,在研究内容上应特别注重系统性和综合性的研究,在方法论上还需充分重视质性研究和量化研究的紧密结合、思辨分析与实证调查的紧密结合. 相似文献
93.
Consider a supply chain with one supplier and multiple retailers. The supplier produces a single product and sells it to the retailers, who in turn sell the product to consumers. The supplier has limited production capacity, and the retailers are engaged in a Cournot competition at the consumer/market level. When the sum of the retailer orders exceeds the capacity, the supplier allocates her capacity according to a pre‐announced allocation mechanism. Two mechanisms are considered: proportional allocation and lexicographic allocation. An extensive study of the two allocation mechanisms shows that the lexicographic mechanism has the ability to dampen the competition at the retail level, increasing the profits for both the supplier and the supply chain. 相似文献
94.
劳动合同法明确了限制违约金的立法模式取代了以往任意约定违约金的立法模式。随着中国建立法治社会目标的不断明确,劳动合同违约金制度的新问题也随之而来。本文通过研究劳动合同违约金制度存在的问题,提出了一些完善劳动合同违约金制度的立法建议。 相似文献
95.
This article discusses regression analysis of current status data, which occur in many fields including cross-sectional studies, demographical investigations, and tumorigenicity experiments (Keiding, 1991; Sun 2006). For the problem, we focus on the situation where the survival time of interest can be described by the additive hazards model and a multiple imputation approach is presented for inference. A major advantage of the approach is its simplicity and it can be easily implemented by using the existing software packages for right-censored failure time data. Extensive simulation studies are conducted and indicate that the approach performs well for practical situations and is comparable to the existing methods. The methodology is applied to a set of current status data arising from a tumorigenicity experiment and the model checking is discussed. 相似文献
96.
Pao-Sheng Shen 《统计学通讯:理论与方法》2013,42(1):128-137
Consider the model φ(S(y | X)) = β(y) T X, where φ is a known link function, S(· | X) is the survival function of a response Y given a covariate X = (1, X, X 2,…, X p ), and β(y) is an unknown vector of time-dependent regression coefficients. The response Y is subject to left truncation and right censoring. We assume that given X, Y is independent of (C, T) where C and T are censoring and truncation variables with P(C ≥ T) = 1. In this article, with some modification of the assumptions in Lemmas 5 and 6 of Iglesias-Pérez and González-Manteiga (1999), we present an almost sure representation for the generalized product-limit estimator (GPL) of S(y | X). Based on the GPL and the approach of Teodorescu et al. (2010), a least squares estimator of β(y) is obtained and a bootstrap procedure is proposed to choose the optimum bandwidth. 相似文献
97.
ABSTRACTCompeting risks data are common in medical research in which lifetime of individuals can be classified in terms of causes of failure. In survival or reliability studies, it is common that the patients (objects) are subjected to both left censoring and right censoring, which is refereed as double censoring. The analysis of doubly censored competing risks data in presence of covariates is the objective of this study. We propose a proportional hazards model for the analysis of doubly censored competing risks data, using the hazard rate functions of Gray (1988), while focusing upon one major cause of failure. We derive estimators for regression parameter vector and cumulative baseline cause specific hazard rate function. Asymptotic properties of the estimators are discussed. A simulation study is conducted to assess the finite sample behavior of the proposed estimators. We illustrate the method using a real life doubly censored competing risks data. 相似文献
98.
ABSTRACTWe investigated the empirical likelihood inference approach under a general class of semiparametric hazards regression models with survival data subject to right-censoring. An empirical likelihood ratio for the full 2p regression parameters involved in the model is obtained. We showed that it converged weakly to a random variable which could be written as a weighted sum of 2p independent chi-squared variables with one degree of freedom. Using this, we could construct a confidence region for parameters. We also suggested an adjusted version for the preceding statistic, whose limit followed a standard chi-squared distribution with 2p degrees of freedom. 相似文献
99.
AbstractFor two components and one standby redundancy, we develop a characterization on the hazard rate order and the reversed hazard rate order of the redundant system lifetime in the context of mutually independent components lifetimes. Also, the likelihood ratio order is derived on the lifetime of the series system with two components lifetimes and two matched active redundancies lifetimes both following the proportional hazard model. 相似文献
100.
Maria Angeles Gil 《统计学通讯:理论与方法》2013,42(4):1521-1526
Several indices of entropy have been suggested in the literature as weighted diversity measures of a population with respect to a classification process. Among them, Shannon's entropy and Havrda -Charvát's non-additive entropies of order a, have been exhaustively used. When the population is finite but too large to be censused, the diversity with respect to a given classification process must be estimated from a sample. In this note, on the basis of an asymptotic study of the sample indices in the stratified random sampling, we are going to confirm that when we deal with large samples one can guarantee a gain in precision from stratified random over simple random sampling. This gain becomes considerable when the ‘inaccuracy" (as intended by Kerridge and Rathie and Kannapan) between the frequency vector in each stratum and that in the whole population, varies greatly from stratum to stratum. 相似文献