Assessing accuracy of a continuous screening test in the presence of verification bias

Summary.  In studies to assess the accuracy of a screening test, often definitive disease assessment is too invasive or expensive to be ascertained on all the study subjects. Although it may be more ethical or cost effective to ascertain the true disease status with a higher rate in study subjects where the screening test or additional information is suggestive of disease, estimates of accuracy can be biased in a study with such a design. This bias is known as verification bias. Verification bias correction methods that accommodate screening tests with binary or ordinal responses have been developed; however, no verification bias correction methods exist for tests with continuous results. We propose and compare imputation and reweighting bias-corrected estimators of true and false positive rates, receiver operating characteristic curves and area under the receiver operating characteristic curve for continuous tests. Distribution theory and simulation studies are used to compare the proposed estimators with respect to bias, relative efficiency and robustness to model misspecification. The bias correction estimators proposed are applied to data from a study of screening tests for neonatal hearing loss.     

研究生导师队伍建设的重要环节——学术论文量化评估

本文从研究生导师队伍科研成果的结构入手 ,认为对导师科研工作评估重点应是对学术论文的量化 ,并提出学术论文量化评估的指标设置、权重系数及其数学模型。     

The evaluation of DNA evidence in pedigrees requiring population inference

Summary. The evaluation of nuclear DNA evidence for identification purposes is performed here taking account of the uncertainty about population parameters. Graphical models are used to detail the hypotheses being debated in a trial with the aim of obtaining a directed acyclic graph. Graphs also clarify the set of evidence that contributes to population inferences and they also describe the conditional independence structure of DNA evidence. Numerical illustrations are provided by re-examining three case-studies taken from the literature. Our calculations of the weight of evidence differ from those given by the authors of case-studies in that they reveal more conservative values.     

A Study to Improve the Method of Ascertaining Attribute Weight Based on Rough Sets Theory

There are some shortages to ascertain attribute weight based on rough set in current studies. In this paper, attrib- ute importance represented by rough set is studied deeply. Aiming at the existing problems, algebra presentation of rough sets is proved to be more comprehensive than its information presentation, then a new method of ascertaining attribute weigh is put forward based on rough set conditional entropy. Finally, it is shown that the new method is more reasonable than the old one by an example.     

广义岭选择指数(英文)

把岭回归的原理和方法应用到家畜性状的选择指数中 ,提出了广义岭选择指数 ,理论和实践证明的这一指数形式在一定意义上优于传统的选择指数。也可以说 ,它在一定意义上丰富了选择指数的理论 ,但不能代替经典的选择指数     

Probability Generating Function Based Jeffrey's Divergence for Statistical Inference

Statistical inference procedures based on transforms such as characteristic function and probability generating function have been examined by many researchers because they are much simpler than probability density functions. Here, a probability generating function based Jeffrey's divergence measure is proposed for parameter estimation and goodness-of-fit test. Being a member of the M-estimators, the proposed estimator is consistent. Also, the proposed goodness-of-fit test has good statistical power. The proposed divergence measure shows improved performance over existing probability generating function based measures. Real data examples are given to illustrate the proposed parameter estimation method and goodness-of-fit test.     

An Improved Distribution-free EWMA Mean Chart

Control charts are effective tools for signal detection in both manufacturing processes and service processes. Much service data come from a process with variables having nonnormal or unknown distributions. The commonly used Shewhart variable control charts, which depend heavily on the normality assumption, should not be properly used here. In this article, we propose an improved asymmetric EWMA mean chart based on a simple statistic to monitor process mean shift. We explored the sampling properties of the new monitoring statistic and calculated the average run lengths of the proposed asymmetric EWMA mean chart. We recommend the proposed improved asymmetric EWMA mean chart because the average run lengths of the modified charts are more accurate and reasonable than those of the five existed mean charts. A numerical example of service times with a right skewed distribution from a service system of a bank branch is used to illustrate the application of the improved asymmetric EWMA mean chart and to compare it with the five existing mean charts. The proposed chart showed better detection performance than those of the five existing mean charts in monitoring and detecting shifts in the process mean.     

中庸与中道思想比较研究

中国的孔子和古希腊的亚里士多德在相似的历史时期提出了共同的中庸和中道思想,对世界文化思想的发展均产生了重大影响.在我们建设全面小康、构建和谐社会的今天,有必要从其产生的历史背景、含义、内容、实现途径以及各自对后世的影响这些方面对这一人类思想史上的优秀成果进行剖析,以充分吸收这一思想的精华,古为今用,洋为中用.     

Status and competitive choice

In this paper, we extend the logic of existing sociological theory on status to explain how status processes can inform selection in competitive choice situations. We argue that in the absence of knowledge about the specific abilities of others and assuming a desire to win, when given the opportunity to “pick their battles,” people will draw on overt status differences as a basis for selecting a competitor from a pool of possible competitors. Results from three studies indicate that, as predicted, status differences affect competitor selection, with individuals choosing to compete against those who are relatively lower status based on diffuse characteristics. Moreover, consistent with expectation state theories, results from two studies show that the expectations that people form for their potential competitors based on status differences mediate this relationship. We conclude by discussing the implications of this research.     

Generalized estimator of population mean by using conventional and non-conventional measures in the presence of measurement errors

In survey research, it is assumed that reported response by the individual is correct. However, given the issues of prestige bias, self-respect, respondent's reported data often produces estimated values which are highly deviated from the true values. This causes measurement error (ME) to be present in the sample estimates. In this article, the estimation of population mean in the presence of measurement error using information on a single auxiliary variable is studied. A generalized estimator of population mean is proposed. The class of estimators is obtained by using some conventional and non-conventional measures. Simulation and numerical study is also conducted to assess the performance of estimators in the presence and absence of measurement error.