A monte carlo study of the LN statistic for the multivariate nonparametric median and rank sum tests for two populations

Small sample tables are not available for the multisample multivariate rank sum test (MMRST) or the multisample multivariate median test (MMMT) L_N statistic. Consequently, the statistic usually is compared to its asymptotic Chi-square value. To investigate the appropriateness of this procedure a Monte Carlo study is used to measure both significance level and relative power for a variety of multivariate dispersion structures.     

The World of Research Has Gone Berserk: Modeling the Consequences of Requiring “Greater Statistical Stringency” for Scientific Publication

ABSTRACT

In response to growing concern about the reliability and reproducibility of published science, researchers have proposed adopting measures of “greater statistical stringency,” including suggestions to require larger sample sizes and to lower the highly criticized “p?<?0.05” significance threshold. While pros and cons are vigorously debated, there has been little to no modeling of how adopting these measures might affect what type of science is published. In this article, we develop a novel optimality model that, given current incentives to publish, predicts a researcher’s most rational use of resources in terms of the number of studies to undertake, the statistical power to devote to each study, and the desirable prestudy odds to pursue. We then develop a methodology that allows one to estimate the reliability of published research by considering a distribution of preferred research strategies. Using this approach, we investigate the merits of adopting measures of “greater statistical stringency” with the goal of informing the ongoing debate.     

论中国现代短篇小说的缘起

短篇小说的创作自清末民初开始复苏,此时期几乎所有的事物都表现出了既现代、又保守的过渡性特征,短篇小说也不例外。说它现代,是在形式上开始借鉴西方;说它保守,则是其现代化的步伐迈得还不够彻底,尤其在精神内涵上,它还与传统母体藕断丝连,甚至貌"离"神"合"。但不管怎么说,清末民初现代短篇小说创作已经起步,并且其创作上的经验和努力,已经为"五四"短篇小说的发展和迅速繁荣铺设了一个宽广的平台。     

汉魏六朝“耕隐”作品的文学史意义——以《文选》中“耕隐”作品为例

《文选》中的诗文表现归隐行为或归隐意念的"耕"及耕作名目,称为"耕隐"作品。先秦典籍中安平乐道思想是源泉,汉魏六朝"耕隐"作品则是流变。从杨恽以"耕"为谋生手段,至张衡有愿望而无"耕隐"实践,再到陶渊明真正践行"耕隐"愿望,是逐渐演进的过程,其中的重要作品均为名作。田园诗是"耕隐"作品成熟的标志;耕作由零散提及至田园诗成为重要诗歌题材,描述诗人"耕隐"心态,表现怡然自得心境;"耕隐"作品影响巨大,形成"桃源"文化现象。     

What Have We (Not) Learnt from Millions of Scientific Papers with P Values?

ABSTRACT

P values linked to null hypothesis significance testing (NHST) is the most widely (mis)used method of statistical inference. Empirical data suggest that across the biomedical literature (1990–2015), when abstracts use P values 96% of them have P values of 0.05 or less. The same percentage (96%) applies for full-text articles. Among 100 articles in PubMed, 55 report P values, while only 4 present confidence intervals for all the reported effect sizes, none use Bayesian methods and none use false-discovery rate. Over 25 years (1990–2015), use of P values in abstracts has doubled for all PubMed, and tripled for meta-analyses, while for some types of designs such as randomized trials the majority of abstracts report P values. There is major selective reporting for P values. Abstracts tend to highlight most favorable P values and inferences use even further spin to reach exaggerated, unreliable conclusions. The availability of large-scale data on P values from many papers has allowed the development and applications of methods that try to detect and model selection biases, for example, p-hacking, that cause patterns of excess significance. Inferences need to be cautious as they depend on the assumptions made by these models and can be affected by the presence of other biases (e.g., confounding in observational studies). While much of the unreliability of past and present research is driven by small, underpowered studies, NHST with P values may be also particularly problematic in the era of overpowered big data. NHST and P values are optimal only in a minority of current research. Using a more stringent threshold, as in the recently proposed shift from P < 0.05 to P < 0.005, is a temporizing measure to contain the flood and death-by-significance. NHST and P values may be replaced in many fields by other, more fit-for-purpose, inferential methods. However, curtailing selection biases requires additional measures, beyond changes in inferential methods, and in particular reproducible research practices.     

论马克思主义的求真精神

马克思主义的求真精神贯穿于马克思主义的产生发展传播的历程中。马克思主义的求真精神不是抽象的、孤立的意识形式,有着实践支撑和价值取向,在社会主义的中国就表现为集体主义的价值观。中国共产党人根据不同的历史和实践提出了不同的具有马克思主义求真精神的指导思想,促进了中国改革和发展的进步。马克思主义的求真精神对规范市场经济条件下的人们的行为、建立诚信原则有着重要的指导作用。     

弗洛斯特诗歌之审美现代性特色研究

所谓现代主义即审美现代性,是对现代工业社会的一种启蒙性的反思与重构。弗洛斯特就是一位具有强烈现代性意识的诗人,他的诗歌的现代性主要表现在3个方面：一是主题中的现代性内容,二是诗歌创作中具有新时代意义的表现手段,三是诗歌韵律上声音效果的创新。     

尼克松时期美国与朝鲜关系的缓和

1953年朝鲜战争结束后,美朝关系陷入了紧张状态,美国对朝鲜民主主义共和国实行了全面遏制政策。但到了尼克松时期,面对当时美国深陷越战和美苏对峙,国力相对衰弱的状况,尼克松政府从美国国家利益出发,开始大规模调整美国的对外政策。对朝政策作为尼克松政府对亚洲政策的一部分,也经历了一个相对缓和的阶段。尼克松时期美朝关系的相对缓和,对美国、朝鲜乃至整个东北亚地区的安全与稳定均产生了一定的积极意义。     

Do we really need confidence intervals in the new statistics?

This paper compares the use of confidence intervals (CIs) and a sensitivity analysis called the number needed to disturb (NNTD), in the analysis of research findings expressed as ‘effect’ sizes. Using 1,000 simulations of randomised trials with up to 1,000 cases in each, the paper shows that both approaches are very similar in outcomes, and each one is highly predictable from the other. CIs are supposed to be a measure of likelihood or uncertainty in the results, showing a range of possible effect sizes that could have been produced by random sampling variation alone. NNTD is supposed to be a measure of the robustness of the effect size to any variation, including that produced by missing data. Given that they are largely equivalent and interchangeable under the conditions tested here, the paper suggests that both are really measures of robustness. It concludes that NNTD is to be preferred because it requires many fewer assumptions, is more tolerant of missing data, is easier to explain, and directly addresses the key question of whether the underlying effect size is zero or not.     

A study of geometric and statistical curvatures for the skew-normal family of distributions

With special reference to the family of skew-normal distributions, we consider geometric curvature of a probability density function as a means to define and identify rare or catastrophic events—a phenomenon common in studying the financial instruments. Further, we study the statistical curvature properties of this family of distributions and discuss the sample size issue, to assess, to what extent the linear and likelihood-based inference of exponential family of distribution can be applicable for the skew-normal family.