An approximation of logarithmic functions in the regression setting

We consider a method of moments approach for dealing with censoring at zero for data expressed in levels when researchers would like to take logarithms. A Box–Cox transformation is employed. We explore this approach in the context of linear regression where both dependent and independent variables are censored. We contrast this method to two others, (1) dropping records of data containing censored values and (2) assuming normality for censored observations and the residuals in the model. Across the methods considered, where researchers are interested primarily in the slope parameter, estimation bias is consistently reduced using the method of moments approach.     

变换法在解微分方程中的应用

变量代换法是解常微分方程的一种辅助方法，它能使问题简化．本文通过联系实例给出了变换在求解微分方程中的具体应用。     

用Excel统计数值型数据频数分布的三种方法

本文根据两种不同的数据分组方式,分别讨论了利用Excel软件统计数值型数据频数分布的三种基本方法并作了简要评述。     

Modeling cooperation among self-interested agents: a critique

This paper reviews recent attempts to model cooperation in groups of self-interested unrelated individuals. It concludes that no empirically plausible model has been developed, and the economist's quest for an explanation of human prosociality in terms of self-interested agents has not been successful. We show that the equilibrium criteria employed in standard game-theoretic models have no attractive dynamic properties, and the mechanisms deployed in these models are not generally seen in empirical examples of cooperative groups. We also show that these models are not robust to plausible rates of signaling error and mutation. We present an alternative, involving strongly reciprocal agents, that satisfies all the requirements for a dynamically stable model of cooperation.     

浅探交际教学法和语法教学法在英语教学中的结合

通过分析交际教学法和语法教学法自身的特点和各自在英语教学中的优势与局限 ,指出将两者结合应用应是现阶段大学英语教学最理想的教学模式 ,并从教学目的、教学对象和教师自身角度说明了这种结合应用的必要性。在此基础上 ,总结了目前在结合应用实践中发现的问题 ,并提出了相应的解决办法。     

《洛阳伽蓝记》里的单纯词

本文具体分类研究了《洛阳伽蓝记》中各种类型的单纯词,简要概括了单纯词在汉语词汇史上的地位。     

Asymptotic bias in the linear mixed effects model under non-ignorable missing data mechanisms

Summary.  In longitudinal studies, missingness of data is often an unavoidable problem. Estimators from the linear mixed effects model assume that missing data are missing at random. However, estimators are biased when this assumption is not met. In the paper, theoretical results for the asymptotic bias are established under non-ignorable drop-out, drop-in and other missing data patterns. The asymptotic bias is large when the drop-out subjects have only one or no observation, especially for slope-related parameters of the linear mixed effects model. In the drop-in case, intercept-related parameter estimators show substantial asymptotic bias when subjects enter late in the study. Eight other missing data patterns are considered and these produce asymptotic biases of a variety of magnitudes.     

Influence diagnostics and outlier tests for semiparametric mixed models

Summary. Semiparametric mixed models are useful in biometric and econometric applications, especially for longitudinal data. Maximum penalized likelihood estimators (MPLEs) have been shown to work well by Zhang and co-workers for both linear coefficients and nonparametric functions. This paper considers the role of influence diagnostics in the MPLE by extending the case deletion and subject deletion analysis of linear models to accommodate the inclusion of a nonparametric component. We focus on influence measures for the fixed effects and provide formulae that are analogous to those for simpler models and readily computable with the MPLE algorithm. We also establish an equivalence between the case or subject deletion model and a mean shift outlier model from which we derive tests for outliers. The influence diagnostics proposed are illustrated through a longitudinal hormone study on progesterone and a simulated example.     

创作方法:文学理论不该遗弃的概念

创作方法概念不该遗弃,而应重新认识其内涵和层次。本文认为,创作方法包括三个基本要素,即创作目的、创作对象和创作原则。具体创作对象的差异以及三要素的不同组合方式使得创作方法具有无限丰富的形态。风格的多样反映了创作方法的多样。以这种新的创作方法概念,可以对许多纠缠不清的问题,如创作方法与世界观、文艺思潮及风格流派的关系问题等,作出新的解释。     

教育技术系统方法在幼儿教育中的应用个案

运用教育技术系统方法开展教学活动,对于幼儿教育同样适用,在幼儿教育中使用系统方法,整合信息技术,让幼儿从小接受多角度、全方位的思维训练。现以一次成功运用系统方法的幼教实践活动作为案例,提取其中的主要步骤进行分析,抛出幼儿教育推广系统方法之砖。