Hypothesis Testing of Hazard Ratio Parameters in Marginal Models for Multivariate Failure Time Data

Marginal hazard models for multivariate failure time data have been studied extensively in recent literature. However, standard hypothesis test statistics based on the likelihood method are not exactly appropriate for this kind of model. In this paper, extensions of the three commonly used likelihood hypothesis test statistics are discussed. Generalized Wald, generalized score and generalized likelihood ratio tests for hazard ratio parameters in a marginal hazard model for multivariate failure time data are proposed and their asymptotic distributions examined. The finite sample properties of these statistics are studied through simulations. The proposed method is applied to data from Busselton Population Health Surveys.     

关于微机应用于教学实习的探讨

本文指出了学生在微机教学实习中出现的若干问题，探讨了解决这些问题的方法。     

我国行政伦理失范成因的社会文化环境分析

当前我国行政伦理失范的重要成因之一是几千年来我国传统文化对人们私人选择和公共选择行为的作用。文章试图通过对中国传统文化中的"官本位"、"人伦文化"以及"非规则化的规则化"3个部分来解释当前行政人员伦理失范行为的文化基础,指出正确地认识社会文化环境在当前发挥的强大惯性和运作基础,对于我国行政伦理的重构具有重要的现实意义。     

Choice of Parametric Accelerated Life and Proportional Hazards Models for Survival Data: Asymptotic Results

We discuss the impact of misspecifying fully parametric proportional hazards and accelerated life models. For the uncensored case, misspecified accelerated life models give asymptotically unbiased estimates of covariate effect, but the shape and scale parameters depend on the misspecification. The covariate, shape and scale parameters differ in the censored case. Parametric proportional hazards models do not have a sound justification for general use: estimates from misspecified models can be very biased, and misleading results for the shape of the hazard function can arise. Misspecified survival functions are more biased at the extremes than the centre. Asymptotic and first order results are compared. If a model is misspecified, the size of Wald tests will be underestimated. Use of the sandwich estimator of standard error gives tests of the correct size, but misspecification leads to a loss of power. Accelerated life models are more robust to misspecification because of their log-linear form. In preliminary data analysis, practitioners should investigate proportional hazards and accelerated life models; software is readily available for several such models.     

Semiparametric Inference Methods for General Time Scale Models

In this paper we consider semiparametric inference methods for the time scale parameters in general time scale models (Oakes, 1995, Duchesne and Lawless, 2000). We use the results of Robins and Tsiatis (1992) and Lin and Ying (1995) to derive a rank-based estimator that is more efficient and robust than the traditional minimum coefficient of variation (min CV) estimator of Kordonsky and Gerstbakh (1993) for many underlying models. Moreover, our estimator can readily handle censored samples, which is not the case with the min CV method.     

论可持续发展背景下经济发展与环境的协调

从经济分析的角度，作者分析了可持续发展过程中环境恶化的经济原因，即市场失灵和政府失灵；揭示出经济发展与环境保护之间存在的倒U型曲线的内在关系。     

大学生英语口语中常见语用失误分析及策略研究

在大学英语教学改革的背景下,英语教师越来越重视口语教学。但学生口语中语用失误的频频发生影响了教学的效果。这其中既有教师"教"的原因,也有学生"学"的原因。从语用学角度出发,剖析常见语用失误产生的原因,加强教师对语用失误的认识,培养学生语用能力和语用移情的习惯是一种比较好的策略,将对解决这一问题起到积极的作用。     

论韩侂胄与开禧北伐

南宋重臣韩■胄领导的开禧北伐，在思想上、政治上、军事上都作了较充分的准备，符合历史发展趋势，故能以胜利开始，但由于朝廷的腐朽、投降派的猖獗、主和派得势、秦桧余党的卑劣、内部的叛徒和用人不当等等原因，终以失败告终，故开禧北伐并非没有准备和自不量力，更不能把韩■胄当奸臣对待。     

A time series approach to life table construction

This paper deals with the construction of the life table. A discussion of basic facts about the life table is followed by the proposal of a nonstationary, autoregressive model for the life table. The moment structure of the nonstationary, autoregressive model is developed. Some estimation procedures are proposed followed by several examples.     

Innovations to Make Markets More Inclusive for the Poor

Market failures, government failures and some of the characteristics of both the poor and business actors as well as their environment can act as barriers preventing the poor from participating more actively in markets, both as consumers and as producers. Private actors ‐ including for‐profit and not‐for‐profit entities, often in partnership with the public sector ‐ have been able to mitigate some of these constraints through innovations that have helped to make markets more inclusive for the poor, enabling them not just to gain access, but also to participate in ways that enhance their economic empowerment and human development. This article identifies the strategies and innovations used and devises a possible typology for them.