Improved sib-pair linkage test for disease susceptibility loci

An improved sib-pair test for linkage is introduced which is superior to the previously proposed tests. The test is derived from the standard chi-squared goodness of fit statistic by restricting the alternative hypothesis to the genetically possible. Critical values are given and exact power comparisons are made with the previously proposed tests. The new test is shown to be more powerful for finite samples as well as being asymptotically uniformly most powerful. © 1993 Wiley-Liss, Inc.     

The Evaluation of Routine Andrological Parameters in Human Semen/Auswertung der Routine-Parameter der Andrologie am Sperma

A study was carried out to evaluate the andrological parameters in 540 human semen specimens divided into groups according to sperm counts. The parameters were: motility percentage and grade, percentage of viability and of morphologically normal sperm and immature cells. The Duncan multiple range test and the Kruskal-Wallis test with multiple comparison of ranks were used in the statistical analyses. Of particular interest, among other our findings, were the significant differences obtained by comparing the group with sperm counts up to 5 x 10(6) per ml semen and that with counts ranging from 5.1 to 10 x 10(6) per ml semen. This was true for all parameters with the exception of semen volume. Comparison of the oligozoospermic groups (up to 20 x 10(6)/ml) with those having higher sperm counts also showed significant differences. There was a trend towards improvement of the examined parameters with the increase in sperm density, but with a remarkable heterogeneity particularly within the oligozoospermic groups. In all groups motility, viability and morphological normality of sperm showed a positive correlation with each other. "Normal values" of the parameters studied could be derived from scatterplot charts over the entire range of sperm counts and from the statistical evaluation of the grouped material.     

医学显微图像分割方法研究进展

医学显微图像分割是医学图像处理中的一个经典难题.针对近年来出现的新方法、新理论,对各种分割方法进行了系统论述,主要包括基于数学形态学方法、神经网络分割、模糊分割、小波分析、遗传算法、统计方法和基于特定模型等方法的图像分割.由于显微图像的复杂性,采用单一方法很难准确分割,故对混合方法也作了一定论述.文中还简要讨论了各种方法的特点和局限性.同时对分割的评价体系也做了简要论述.     

Evaluating the accuracy of a geographic closed-ended approach to ethnicity measurement,a practical alternative

PurposeMeasuring ethnicity accurately is important for identifying ethnicity variations in disease risk. We evaluated the degree of agreement and accuracy of maternal ethnicity measured using the new standardized closed-ended geographically based ethnicity question and geographic reclassification of open-ended ethnicity questions from the Canadian census.MethodsA prospectively designed study of respondent agreement of mothers of healthy children aged 1–5 years recruited through the TARGet Kids! practice-based research network. For the primary analysis, the degree of agreement between geographic reclassification of the Canadian census maternal ethnicity variables and the new geographically based closed-ended maternal ethnicity variable completed by the same respondent was evaluated using a kappa analysis.ResultsEight hundred sixty-two mothers who completed both measures of ethnicity were included in the analysis. The kappa agreement statistic for the two definitions of maternal ethnicity was 0.87 (95% confidence interval, 0.84–0.90) indicating good agreement. Overall accuracy of the measurement was 93%. Sensitivity and specificity ranged from 83% to 100% and 96% to 100%, respectively.ConclusionsThe new standardized closed-ended geographically based ethnicity question represents a practical alternative to widely used open-ended ethnicity questions. It may reduce risk of misinterpretation of ethnicity by respondents, simplify analysis, and improve the accuracy of ethnicity measurement.     

Testing for changing volatility

In this paper, we propose a consistent U‐statistic test with good sampling properties to detect changes in volatility. We show that the test has a limiting standard normal distribution under the null hypothesis, and that it is powerful compared with various alternatives. A Monte Carlo experiment is conducted to highlight the merits of the proposed test relative to other popular tests for structural changes in volatility. An empirical example is examined to demonstrate the practical application of the proposed testing method.     

Testing a parametric function against a non‐parametric alternative in IV and GMM settings

Summary This paper develops a specification test for functional form for models identified by a conditional moment restriction, including IV and GMM settings. The framework is one where the moment restriction is specified as a function of data, a finite‐dimensional parameter vector and a non‐parametric function (an infinite‐dimensional parameter vector). The null hypothesis is that the moment restriction does not depend on the non‐parametric function. The test is relatively easy to implement and its asymptotic distribution is known. The test performs well in simulation experiments.     

Dissolution Curve Comparisons Through the F2 Parameter,a Bayesian Extension of the f2 Statistic

Dissolution (or in vitro release) studies constitute an important aspect of pharmaceutical drug development. One important use of such studies is for justifying a biowaiver for post-approval changes which requires establishing equivalence between the new and old product. We propose a statistically rigorous modeling approach for this purpose based on the estimation of what we refer to as the F₂ parameter, an extension of the commonly used f₂ statistic. A Bayesian test procedure is proposed in relation to a set of composite hypotheses that capture the similarity requirement on the absolute mean differences between test and reference dissolution profiles. Several examples are provided to illustrate the application. Results of our simulation study comparing the performance of f₂ and the proposed method show that our Bayesian approach is comparable to or in many cases superior to the f₂ statistic as a decision rule. Further useful extensions of the method, such as the use of continuous-time dissolution modeling, are considered.     

我国护理期刊学术影响力排名分析

[目的]分析我国护理期刊学术影响力排名,综合评价我国21种护理学统计源期刊学术影响力。[方法]以2014年版《中国科技期刊引证报告》(扩刊版)中21种护理期刊为研究对象,以总被引频次、影响因子、他引总引比、高被引论文数、来源文献量、平均引文数、地区分布数、Web下载量共8项指标为依据,赋予各项指标不同的权重,运用归一化加权法综合评价21种护理期刊的学术影响力。[结果]2014年21种护理学统计源期刊与全国6 345种科技期刊6项评价指标比较显示,总被引频次、影响因子、他引总引比、来源文献量、地区分布数5项评价指标均显著高于科技期刊平均水平,但平均引文数显著低于我国科技期刊的平均水平;运用多指标归一化加权法得出21种护理学统计源期刊的综合值,排名前5位的依次为《中华护理杂志》《护理研究》《中国实用护理杂志》《护士进修杂志》和《护理学杂志》;将本研究护理核心期刊排名情况与《中国科技期刊引证报告》进行比较,部分期刊在2个评价体系中排名有不同程度的上升或下降,存在综合值排名与影响因子排名分离的现象。[结论]我国护理期刊整体影响力较科技期刊平均水平高,但护理科研论文质量较其他科技期刊存在较大差距;运用多指标数据归一化加权法综合评价我国21种护理学统计源期刊的学术影响力,能作出全面、科学、准确的评价,真实反映护理期刊的影响力,能够为护理学术期刊自身发展及提高期刊影响力提供改进方向。     

Type I error probability spending for post–market drug and vaccine safety surveillance with binomial data

Type I error probability spending functions are commonly used for designing sequential analysis of binomial data in clinical trials, but it is also quickly emerging for near–continuous sequential analysis of post–market drug and vaccine safety surveillance. It is well known that, for clinical trials, when the null hypothesis is not rejected, it is still important to minimize the sample size. Unlike in post–market drug and vaccine safety surveillance, that is not important. In post–market safety surveillance, specially when the surveillance involves identification of potential signals, the meaningful statistical performance measure to be minimized is the expected sample size when the null hypothesis is rejected. The present paper shows that, instead of the convex Type I error spending shape conventionally used in clinical trials, a concave shape is more indicated for post–market drug and vaccine safety surveillance. This is shown for both, continuous and group sequential analysis.