Testing symmetry based on empirical likelihood

In this paper, we propose a general kth correlation coefficient between the density function and distribution function of a continuous variable as a measure of symmetry and asymmetry. We first propose a root-n moment-based estimator of the kth correlation coefficient and present its asymptotic results. Next, we consider statistical inference of the kth correlation coefficient by using the empirical likelihood (EL) method. The EL statistic is shown to be asymptotically a standard chi-squared distribution. Last, we propose a residual-based estimator of the kth correlation coefficient for a parametric regression model to test whether the density function of the true model error is symmetric or not. We present the asymptotic results of the residual-based kth correlation coefficient estimator and also construct its EL-based confidence intervals. Simulation studies are conducted to examine the performance of the proposed estimators, and we also use our proposed estimators to analyze the air quality dataset.     

中国英语学习者写作中的迁移性冗余

冗余是语言和言语交际的固有特征.它不仅与信息相关,而且与语言表达相关.在用英语写作时,中国英语学习者常常将汉语中的语言规则应用到英语作文中,造成冗长和重复性的表达,这种迁移性冗余妨碍了交流的效率.迁移性冗余主要体现在三个层面:句子、段落和语篇,其产生原因与中国人的哲学思想、思维方式及汉语的使用规则和习惯密切相关,了解其表现形式和产生缘由有助于消除这一类的冗余,提高交流的流畅性.     

What Influences the Growth of the Chinese Nonprofit Sector: A Prefecture-Level Study

The nonprofit sector in China has experienced unprecedented growth in its scope and impact over the past four decades. Despite the significant growth, the distribution of nonprofit activities across localities is not well understood. This study combines administrative and census data to examine the size of the Chinese nonprofit sector across 334 prefectures. The study demonstrates a significant variation in nonprofit sector size across prefectures. The study further shows that population heterogeneity, government social spending, and government fragmentation have positive effects on boosting nonprofit sector size in a prefecture. Although diverse service needs affect the growth of the Chinese nonprofit sector, government activities play a more important role in mobilizing nonprofit activities and driving nonprofit sector growth.     

Joint analysis of longitudinal data and competing terminal events in the presence of dependent observation times with application to chronic kidney disease

In many prospective clinical and biomedical studies, longitudinal biomarkers are repeatedly measured as health indicators to evaluate disease progression when patients are followed up over a period of time. Patient visiting times can be referred to as informative observation times if they are assumed to carry information in addition to that of the longitudinal biomarker measures alone. Irregular visiting times may reflect compliance with physician instruction, disease progression and symptom severity. When the follow-up time may be stopped by competing terminal events, it is possible that patient observation times may correlate with the competing terminal events themselves, thus making the observation times difficult to assess. To explicitly account for the impact of competing terminal events and dependent observation times on the longitudinal data analysis in the context of such complex data, we propose a joint model using latent random effects to describe the association among them. A likelihood-based approach is derived for statistical inference. Extensive simulation studies reveal that the proposed approach performs well for practical situations, and an analysis of patients with chronic kidney disease in a cohort study is presented to illustrate the proposed method.     

我国粮食安全状况的实证分析

粮食安全问题始终是关系到国民经济发展的最基本和最重要的问题.本文使用SWOT分析方法对我国粮食安全的基本情况(优势,劣势,机会,威胁)进行了系统的阐述和客观的判断,并使用主成分分析法对我国粮食安全状况进行了实证分析.计算出了我国1983-2006年历年的粮食安全指数,同时指出了我国不同时期粮食安全状况变化的原因.当然,安全是一个动态概念,不同的经济发展水平或经济发展时期有不同的安全概念.从现阶段我国的实际情况来看,当国内粮食市场呈现出供求平衡、价格稳定、政策有效以及农民种粮收益能够得到保障的特点时,我国的粮食安全程度是比较高的.     

关于课堂英语口语教学的几点建议

本文提出提高英语口语教学效果的相关问题，并提出几点建议。     

Data envelopment analysis 1978–2010: A citation-based literature survey

This study surveys the data envelopment analysis (DEA) literature by applying a citation-based approach. The main goals are to find a set of papers playing the central role in DEA development and to discover the latest active DEA subareas. A directional network is constructed based on citation relationships among academic papers. After assigning an importance index to each link in the citation network, main DEA development paths emerge. We examine various types of main paths, including local main path, global main path, and multiple main paths. The analysis result suggests, as expected, that Charnes et al. (1978) [Charnes A, Cooper WW, Rhodes E. Measuring the efficiency of decision making units. European Journal of Operational Research 1978; 2(6): 429–444] is the most influential DEA paper. The five most active DEA subareas in recent years are identified; among them the “two-stage contextual factor evaluation framework” is relatively more active. Aside from the main path analysis, we summarize basic statistics on DEA journals and researchers. A growth curve analysis hints that the DEA literature’s size will eventually grow to at least double the size of the existing literature.     

《皮裹腿故事集》的绿色解读

库柏的<皮裹腿故事集>是最早记录美国西进扩张历史的浪漫主义文学作品,描绘了自然之子纳蒂·邦波在北美荒野的精彩冒险活动,叙述了北美荒野让位于城镇、村庄的文明化过程,奠定了美国文学中的一个恒久主题:文明与自然的冲突.在生态危机日益严峻的今天,重读近两百年前库柏提出的美国进步发展史中的生态问题,为我们提供了培养在自然面前保持谦卑意识,重审美国"进步"概念的着手点.     

国内伊格尔顿研究教材定位的局限性

国内相关教材一般将英国理论家伊格尔顿定位为西方马克思主义文论家,对其文艺思想的研究局限于文学生产理论、意识形态理论及政治批评理论,但这些基本上是伊格尔顿早期作品的理论内容,不能反映伊格尔顿思想的全貌.此外,教材对有关伊格尔顿意识形态理论的最新研究成果应用较少,教材内容存在滞后、单一、雷同之弊端.教材定位的局限性势必影响研究视界的多样化发展,学界对伊格尔顿近期学术动向尤其是文化理论的研究不够充分,虽然讨论了伊格尔顿的后现代主义批判理论,但是缺乏系统考察和理论重视.