The Detection of Influential Observations for Allocation,Separation, and the Determination of Probabilities in a Bayesian Framework

Normal theory separation and allocation problems are discussed from a predictive point of view. Influence statistics are defined and employed to ascertain the impact that particular observations will have on the inferential goals—allocation of future observations, separation between populations, and the determination of probabilities for future cases. Methods are illustrated on a collection of financial data taken from Johnson and Wichern (1982).     

Asymptotic Properties and Variance Estimators of the M-quantile Regression Coefficients Estimators

M-quantile regression is defined as a “quantile-like” generalization of robust regression based on influence functions. This article outlines asymptotic properties for the M-quantile regression coefficients estimators in the case of i.i.d. data with stochastic regressors, paying attention to adjustments due to the first-step scale estimation. A variance estimator of the M-quantile regression coefficients based on the sandwich approach is proposed. Empirical results show that this estimator appears to perform well under different simulated scenarios. The sandwich estimator is applied in the small area estimation context for the estimation of the mean squared error of an estimator for the small area means. The results obtained improve previous findings, especially in the case of heteroskedastic data.     

Influence Diagnostics of Semiparametric Nonlinear Reproductive Dispersion Models

This article proposes a semiparametric nonlinear reproductive dispersion model (SNRDM) which is an extension of nonlinear reproductive dispersion model and semiparametric regression model. Maximum penalized likelihood estimators (MPLEs) of unknown parameters and nonparametric functions in SNRDMs are presented. Some novel diagnostic statistics such as Cook distance and difference deviance for parametric and nonparametric parts are developed to identify influence observations in SNRDMs on the basis of case-deletion method, and some formulae readily computed with the MPLEs algorithm for diagnostic measures are given. The equivalency of case-deletion models and mean-shift outlier models in SNRDM is investigated. A simulation study and a real example are used to illustrate the proposed diagnostic measures.     

Robust Estimators for the Parameters of Multivariate Lognormal Distribution

Abstract

In this paper, we introduce a class of location and scale estimators for the p-variate lognormal distribution. These estimators are obtained by applying a log transform to the data, computing robust Fisher consistent estimators for the obtained Gaussian data and transforming those estimators for the lognormal using the relationship between the parameters of both distributions. We prove some of the properties of these estimators, such as Fisher consistency, robustness and asymptotic normality.     

The generalized log-gamma mixture model with covariates: local influence and residual analysis

In a sample of censored survival times, the presence of an immune proportion of individuals who are not subject to death, failure or relapse, may be indicated by a relatively high number of individuals with large censored survival times. In this paper the generalized log-gamma model is modified for the possibility that long-term survivors may be present in the data. The model attempts to separately estimate the effects of covariates on the surviving fraction, that is, the proportion of the population for which the event never occurs. The logistic function is used for the regression model of the surviving fraction. Inference for the model parameters is considered via maximum likelihood. Some influence methods, such as the local influence and total local influence of an individual are derived, analyzed and discussed. Finally, a data set from the medical area is analyzed under the log-gamma generalized mixture model. A residual analysis is performed in order to select an appropriate model. The authors would like to thank the editor and referees for their helpful comments. This work was supported by CNPq, Brazil.     

The professionalization of the 'shoe clerk'

Summary.  The address reviews the professionalization of statisticians working in the regulated world of drug development. The need for statisticians to continue to push the boundaries of their professional environment is stressed. It is argued that to maintain the strength and influence of the profession it is neither desirable, nor necessary, to define in a statutory sense access to the profession.     

大学生主观生活质量及其影响因素研究

大学生的主观生活质量是目前学术领域研究比较薄弱的一个环节。文章通过实证调查所得资料的分析，认为当今大学生的主观生活质量总体上处于比较理想的水平，并通过因子分析和多元回归等统计方法，发现影响大学生主观生活质量的因素首先是学习满意度，其次包括人际关系满意度、精神满意度等10个方面。性别、家庭经济状况和年级对大学生的主观生活质量也有不同程度的影响。     

论藏文化对裕固族及其文化形成的影响

裕固族文化是以古老的回鹊文化为基础,并在与历史上的汉、藏和蒙古等民族文化间的相互交融中形成的。裕固族东迁以前就已信仰了藏传佛教,这是决定裕固族先民的东迁并形成裕固族及其文化的关键因素。藏文化对裕固族及其文化的影响是深远的。     

唐代骠国献乐考

唐德宗贞元年间(785～804年),骠国沿古代西南丝道赴长安献乐。骠国献乐不仅对当时社会产生了重要的政治影响,也构成了唐代中后期中外文化交流的重要内容。作者对骠国献乐的经过和骠国所献乐器、乐曲、乐工及其 乐舞表演的基本情况作了梳理;分析了骠国献乐产生的政治、文化影响。     

论《游仙窟》体制所受汉译佛经影响

《游仙窟》虚构故事的情节链很长并且各个环节连接得都比较紧密自然,受到汉译佛经中同类故事的影响;较大规模地用诗唱和,受到汉译佛经中较大规模地用偈颂对话形式的影响。