Empirical likelihood confidence regions for comparison distributions and roc curves

Abstract: The authors derive empirical likelihood confidence regions for the comparison distribution of two populations whose distributions are to be tested for equality using random samples. Another application they consider is to ROC curves, which are used to compare measurements of a diagnostic test from two populations. The authors investigate the smoothed empirical likelihood method for estimation in this context, and empirical likelihood based confidence intervals are obtained by means of the Wilks theorem. A bootstrap approach allows for the construction of confidence bands. The method is illustrated with data analysis and a simulation study.     

从"贵族民主制"到"等级君主制"的英国

英国是在外族入侵不列颠的基础上发展形成的。在其"等级君主制"形成前的1700多年里大致经历了公元前5世纪盎格鲁人,撒克逊人和朱特人入侵不列颠;公元10世纪统一国家的形成;1066年位于欧洲大陆诺曼底的公爵威廉率军入侵;从威廉二世到亨利二世统治时期的社会改革;1295年英国议会形成等历史阶段,从而使英国政体从"贵族民主制"演变为"等级君主制"。     

Estimation of the Population Size in the Classical Occupancy Problem

In the classical occupancy problem where the random variable X is the number of N elements selected by K individuals when each element is equally likely to be chosen by any of the individuals, it is desired to estimate N. Three estimators given in the literature are compared with three estimators derived in this article, two of which are based on Bayesian methods, utilizing a simulation study. One of the Bayes estimators appears to perform the best along with one proposed in the literature in 1968. The estimators are also compared using data obtained from a cemetery in Ohio.     

Principled leveraging of external data in the evaluation of diagnostic devices via the propensity score-integrated composite likelihood approach

In the area of diagnostics, it is common practice to leverage external data to augment a traditional study of diagnostic accuracy consisting of prospectively enrolled subjects to potentially reduce the time and/or cost needed for the performance evaluation of an investigational diagnostic device. However, the statistical methods currently being used for such leveraging may not clearly separate study design and outcome data analysis, and they may not adequately address possible bias due to differences in clinically relevant characteristics between the subjects constituting the traditional study and those constituting the external data. This paper is intended to draw attention in the field of diagnostics to the recently developed propensity score-integrated composite likelihood approach, which originally focused on therapeutic medical products. This approach applies the outcome-free principle to separate study design and outcome data analysis and can mitigate bias due to imbalance in covariates, thereby increasing the interpretability of study results. While this approach was conceived as a statistical tool for the design and analysis of clinical studies for therapeutic medical products, here, we will show how it can also be applied to the evaluation of sensitivity and specificity of an investigational diagnostic device leveraging external data. We consider two common scenarios for the design of a traditional diagnostic device study consisting of prospectively enrolled subjects, which is to be augmented by external data. The reader will be taken through the process of implementing this approach step-by-step following the outcome-free principle that preserves study integrity.     

《诗经》英译的两大难题及其解决方法

文章就翻译《诗经》过程中可能遇到的两大难题,即如何保持语言的准确性和风格的完整性进行了深入的分析和探讨,从语言的发展、作品的个人风格及民族风格等方面分析了难题产生的原因,此外,还结合JamesLegge所翻译的《诗经》,提出了相应的解决方法,如淡化、阐释和变通等手法。     

Optimal cutoffs for continuous biomarkers for survival data under competing risks

Identifying an optimal cutoff value for a continuous biomarker is often useful for medical applications. For binary outcome, commonly used cutoff finding criteria include Youden's index, classification accuracy, and the Euclidean distance to the upper left corner on the ROC curve. We extend these three criteria to accommodate censored survival time that subjected to competing risks. We provide various definitions of time-dependent true positive rate and false positive rate and estimate those quantities using nonparametric methods. In simulation studies, the Euclidean distance to the upper left corner on the ROC curve shows the best overall performance.     

Assessing point forecast accuracy by stochastic error distance

ABSTRACT

We propose point forecast accuracy measures based directly on distance of the forecast-error c.d.f. from the unit step function at 0 (“stochastic error distance,” or SED). We provide a precise characterization of the relationship between SED and standard predictive loss functions, and we show that all such loss functions can be written as weighted SEDs. The leading case is absolute error loss. Among other things, this suggests shifting attention away from conditional-mean forecasts and toward conditional-median forecasts.     

Individuals’ power and their social network accuracy: A situated cognition perspective

Individuals differ in how accurately they perceive their social environment, but research and theory provide conflicting predictions on whether powerful people are more or less accurate than others. Drawing on social network theory and the situated cognition theory of power, we examine the relationship between individuals’ formal and informal power and their perceptual accuracy of social network relationships. We propose that individuals’ perceptual accuracy is related to: 1) their formal and informal power in the organization; 2) the type of relationship being perceived (positive/negative valence) and its relevance to task and goal completion; and 3) the dependence relationship with the target of perception (i.e., whether the perceiver is dependent on the perceived to get their work done). Predictions were tested using cognitive social structure data collected from a technical call center. Results showed that power was generally linked to increased perceptual accuracy, particularly for the types of relationships most relevant for task and goal completion. We further demonstrated that social network accuracy was related to employees’ outcomes, including subsequent transfer, promotion, and exit from the organization.     

妙哉合肥方言

合肥方言属于非物质文化遗产,它表述文明、词汇丰富、分工细致,比北方话更精密、准确、完善,其中不少语言有音有义而无字,证实了它的古老性。     

提高青少年跳远运动员助跑准确性的实验研究

跳远助跑准确性直接影响跳远技术的正常发挥和比赛成绩,对运动员进行助跑准确性方面的训练已越来越受到重视。本文采用了助跑技术专门训练和心理专门训练相结合的方法,对10名青少年跳远运动员进行了提高助跑准确性的训练。结果表明,这些训练方法能够明显提高运动员的助跑准确性,从而导致跳远成绩的提高。