Sample Size and Power Calculation in Comparing Diagnostic Accuracy of Biomarkers with Pooled Assessments

When testing of a biomarker is costly, pooling of samples becomes a useful and efficient alternative (Faraggi et al., 2003). In this paper, we develop procedures for sample size and power calculations for planning a study comparing the accuracy of biomarkers in diagnosis of diseases with pooled samples. Explicit formulas are derived for several important pooling strategies. The effects of pooling samples on sample size and power of the test are also discussed.     

兔大肠杆菌病原菌的分离鉴定与药敏试验

从重庆市几个种兔场临诊严重腹泻的病兔采集病料 ,分离出 3株菌 ,经形态学检查及生化鉴定 ,呈革兰氏阴性 ,两端钝圆的杆状 ,常规的生化结果均符合大肠杆菌特征 ,但 3株菌对棉子糖、蕈糖的分解及赖氨酸的利用上存在着差异。用青霉素G等 2 0种药物进行药敏试验 ,结果表明 :对头孢类、庆大霉素、妥布霉素、阿米卡星、壮观霉素、痢特灵等敏感 ;对麦迪霉素、强力霉素等中敏 ;而对青霉素G、四环素、链霉素等表现为耐药。其中 1号菌株对喹诺酮类、强力霉素、卡那霉素、复方新诺明等耐药 ,2号菌株对喹诺酮类、氯霉素、卡那霉素等敏感 ,而对复方新诺明、利福平等耐药 ,3号菌株对卡那霉素、氯霉素、强力霉素等敏感 ,而对利福平耐药。该试验结果表明 :在不同兔场 ,感染兔的大肠杆菌的株型不一致 ,并且对药物的敏感性也不一致。     

Sensitivity Analysis for Importance Assessment

We review briefly some examples that would support an extended role for quantitative sensitivity analysis in the context of model-based analysis (Section 1). We then review what features a quantitative sensitivity analysis needs to have to play such a role (Section 2). The methods that meet these requirements are described in Section 3; an example is provided in Section 4. Some pointers to further research are set out in Section 5.     

Properties of a class of inequality measures: A proposal for a resistant version

Summary This note explores the robustness properties of a general class of ineqyality measures which includes the Bonferroni and the Gini indexes as special cases and proposes some modifications in order to make them outlier resistant.     

企业投资项目财务风险性分析

企业投资项目财务风险性分析中,如何看待和处理变量间的相关问题,不仅仅考虑变量的单点估计,而且应考虑动态和相关性。在风险分析中,忽视了相关性而且造成判断的失误,应引起足够的重视;变量之间存在相关性时,首先应进行相关性分析,其次进行相关性条件下的敏感性分析。如此做出的投资项目的风险分析更接近实际情况,减少投资风险,增加投资效益。     

Sensitivity Analysis of Model Output with Input Constraints: A Generalized Rationale for Local Methods

In this work, we introduce a generalized rationale for local sensitivity analysis (SA) methods that allows to solve the problems connected with input constraints. Several models in use in the risk analysis field are characterized by the presence of deterministic relationships among the input parameters. However, SA issues related to the presence of constraints have been mainly dealt with in a heuristic fashion. We start with a systematic analysis of the effects of constraints. The findings can be summarized in the following three effects. (i) Constraints make it impossible to vary one parameter while keeping all others fixed. (ii) The model output becomes insensitive to a parameter if a constraint is solved for that parameter. (iii) Sensitivity analysis results depend on which parameter is selected as dependent. The explanation of these effects is found by proposing a result that leads to a natural extension of the local SA rationale introduced in Helton (1993) . We then extend the definitions of the Birnbaum, criticality, and the differential importance measures to the constrained case. In addition, a procedure is introduced that allows to obtain constrained sensitivity results at the same cost as in the absence of constraints. The application to a nonbinary event tree concludes the article, providing a numerical illustration of the above findings.     

新型微波辐射测试仪的研制

介绍了一种新型微波辐射测试仪的研制。给出了仪器的基本结构，测试原理和主要技术参数。同时详细阐述了仪器的误差分析和定度方法。为微波设备的电磁波泄漏测量提供了一种方便、实用的仪器。     

The feeling edge of culture

During the 1960s, the new generation changed the American Creed by deemphasizing sensitivity to evidence, emphasizing feelings and deductive thought, while assuming an adversarial position against the sociopolitical order and embracing the American Black's struggle against racism. Driven by pain, fueled by fear and anger and oriented by existential values of being, the Civil Rights Movement, sought to actualize political values of justice and equality. As peaceful demonstrations dwindled, violence increased, converting individual anger to social rage. Anger's cognitive structure changed the concept of society into a dichotomy of Black victims and White oppressors, forming an ethic of sensitivity with victims occupying the moral high ground. Pain and tragedy were banished from view and blamed on oppressors as individual identities divested civil traits and acquired cultural identity, disuniting the civil society. Rubbing against the American Creed, the ethic of sensitivity produced a feeling of malaise posing a threat to mental health.     

Tissue Dosimetry, Pharmacokinetic Modeling, and Interspecies Scaling Factors

Interspecies scaling factors (ISFs) are numbers used to adjust the potency factor (for example, the q1* for carcinogens or reference doses for compounds eliciting other toxic endpoints) determined in experimental animals to account for expected differences in potency between test animals and people. ISFs have been developed for both cancer and non-cancer risk assessments in response to a common issue: toxicologists often determine adverse effects of chemicals in test animals and then they, or more commonly risk assessors and risk managers, have to draw inferences about what these observations mean for the human population. This perspective briefly reviews the development of ISFs and their applications in health risk assessments over the past 20 years, examining the impact of pharmacokinetic principles in altering current perceptions of the ISFs applied in these health risk assessments, and assessing future directions in applying both pharmacokinetic and pharmacodynamic principles for developing ISFs.     

M-Estimators of Scale with Minimum Gross Errors Sensitivity

The median absolute deviation (MAD) is known to be the M-estimator of scale with minimum gross errors sensitivity (GES) when the error distribution is known to be symmetric and strongly unimodal. The problem considered here is to find the Fisher consistent M-estimator with minimum GES when the error distribution is symmetric but not necessarily unimodal. Under some general conditions, the score function χ corresponding to the minimizing M-estimator has the form χ(x) = ?1 when |x| < a; χ(x) = c when a < |x| < b; χ(x) = 1 when |x| > b. An example is given in which the M-estimator with minimum GES does not correspond to the MAD.