Aging and ordering properties of multivariate lifetimes with Archimedean dependence structures

This paper further studies monotone aging properties of the multivariate random lifetime. We revise the sufficient condition for the negative monotone aging property in terms of the multivariate usual stochastic order in Theorem 3.3 of Rezapour et al. (2013) Rezapour, M., Alamatsaz, M.H., Pellerey, F. (2013). Multivariate aging with Archimedean dependence structures in high dimensions. Commun. Stat. - Theory Methods 42:2056–2070.[Taylor &; Francis Online], [Web of Science ®] , [Google Scholar] and derive the condition sufficient to the multivariate monotone aging properties in terms of the upper orthant order. Also we study the upper orthant order of multivariate residual lifetimes and inactivity times from populations sharing a common Archimedean survival copula and Archimedean survival copula, respectively. Two simple applications in multivariate stress-strength and frailty models are presented as well.     

公司运营危机预警模型的比较研究——以中国上市公司为例

研究当前国内外公司运营危机预警问题的现状,首先要寻找一套适合于我国上市公司的财务状况识别指标体系,然后依据该指标体系采用不同方法建立运营危机预警模型,最后利用样本公司实际指标数据对各个模型的短期及中期预警效果进行比较分析与实证研究。结果表明,分类树模型的三年期预警准确率都在80%以上。     

MAP segmentation in Bayesian hidden Markov models: a case study

We consider the problem of estimating the maximum posterior probability (MAP) state sequence for a finite state and finite emission alphabet hidden Markov model (HMM) in the Bayesian setup, where both emission and transition matrices have Dirichlet priors. We study a training set consisting of thousands of protein alignment pairs. The training data is used to set the prior hyperparameters for Bayesian MAP segmentation. Since the Viterbi algorithm is not applicable any more, there is no simple procedure to find the MAP path, and several iterative algorithms are considered and compared. The main goal of the paper is to test the Bayesian setup against the frequentist one, where the parameters of HMM are estimated using the training data.     

What do we call post-apartheid?

In this paper, the author examines the different uses and meanings of the usual expression “post-apartheid.” It has been used extensively in the social sciences, political discourse and the media since the mid-1980s. But what does it refer to, and has it always meant the same thing over the last 20 years? To answer that question, the author reviews the different ways she has used the notion in her research into workers’ forms of thinking and political subjectivities in South Africa since 1996. She distinguishes between its use as a chronological marker, an academic concept open to various problematics and epistemological decisions and a notion used by interviewees under various acceptations. She concentrates more specifically on the sequential implications of the adverb “post” in her work and argues that there have been political sequences in what she (with others) has named “post-apartheid.” She concludes that she intends to stop using this term in order to concentrate on identifying the current political sequence in South Africa.     

Alternative Methods for Computing the Sensitivity of Complex Surveillance Systems

Stochastic scenario trees are a new and popular method by which surveillance systems can be analyzed to demonstrate freedom from pests and disease. For multiple component systems—such as a combination of a serological survey and systematically collected observations—it can be difficult to represent the complete system in a tree because many branches are required to represent complex conditional relationships. Here we show that many of the branches of some scenario trees have identical outcomes and are therefore redundant. We demonstrate how to prune branches and derive compact representations of scenario trees using matrix algebra and Bayesian belief networks. The Bayesian network representation is particularly useful for calculation and exposition. It therefore provides a firm basis for arguing disease freedom in international forums.     

A statistical measure of internal consistency

A test for homogeneity of several populations against the simple tree alternative is proposed when the observations in various groups are subject to the same pattern of random right-censorship. The test is a generalization of the one proposed by Slivka (1970) which is useful when testing time is expensive so that an early termination of an experiment is desirable. The power of the test is examined in a simulation study.     

A nonparametric bayesian approach to analysis of drug dependence data

In this paper, a nonparametric Bayesian approach to the analysis of binary response data is considered. Using a Dirichlet process prior, and squared error loss, the Bayes estimators of response probabilities are obtained. Finally, the results obtained are employed to analyze the ARC 090 Trial data.     

Automatic locally adaptive smoothing for tree-based set estimation

Tree-based methods similar to CART have recently been utilized for problems in which the main goal is to estimate some set of interest. It is often the case that the boundary of the true set is smooth in some sense, however tree-based estimates will not be smooth, as they will be a union of ‘boxes’. We propose a general methodology for smoothing such sets that allows for varying levels of smoothness on the boundary automatically. The method is similar to the idea underlying support vector machines, which is applying a computationally simple technique to data after a non-linear mapping to produce smooth estimates in the original space. In particular, we consider the problem of level-set estimation for regression functions and the dyadic tree-based method of Willett and Nowak [Minimax optimal level-set estimation, IEEE Trans. Image Process. 16 (2007), pp. 2965–2979].     

关于抛物线与相交直线围成的弓形面积初等数学解法的探讨

文章运用两种巧妙的分割和利用无究递缩等比数列求和公式等初等数学知识，求出了抛物线与相交直线围成的弓形面积计算公式。