Small-sample degrees of freedom for multi-component significance tests with multiple imputation for missing data

When performing multi-component significance tests with multiply-imputeddatasets, analysts can use a Wald-like test statistic and areference F-distribution. The currently employed degrees offreedom in the denominator of this F-distribution are derivedassuming an infinite sample size. For modest complete-data samplesizes, this degrees of freedom can be unrealistic; for example,it may exceed the complete-data degrees of freedom. This paperpresents an alternative denominator degrees of freedom thatis always less than or equal to the complete-data denominatordegrees of freedom, and equals the currently employed denominatordegrees of freedom for infinite sample sizes. Its advantagesover the currently employed degrees of freedom are illustratedwith a simulation.     

探讨现代医院药剂管理的思路及意义

随着我国医疗体制的改革,医院也面临着新形势下自身管理体系和管理方式的改革和创新。现代医院的管理模式也发生很大变化,从传统经验管理型逐步转变为现代管理型。现代医院管理采用科学的管理方法和管理技术,广泛地运用现代自然科学和社会科学的研究成果使管理手段现代化、科学化。现代医院药剂管理是医院管理工作的重要组成部分,对医疗质量及用药安全起着重要的作用。医院药剂管理的现代化可以保证用药的安全性,提高医疗质量,提高医院的核心竞争力,促进现代市场经济体制下医疗水平的提升和医院的发展。现代医院药剂管理的关键在于如何实现新模式下的管理目标及如何提高新模式下的药剂管理水平。本文结合我院在医疗改革背景下逐渐创新各个环节的管理模式,完善管理体系,突破管理瓶颈而获得的实践体会,进一步探讨现代医院药剂管理的方法及意义,为医院药剂管理工作提供理论指导。     

支原体肺炎患儿血清中相关炎性因子的表达变化情况及其临床意义探讨(英文)

目的:探讨支原体肺炎(Mycoplasma Pneumoniae Pneumonia,MPP)患儿血清中细胞因子IL-8,IL-12的表达水平及hs-CRP、IgG和血清补体(C)的变化及其临床意义。方法:收集MPP患儿50例,分为重症组、轻症组。健康儿童42例作为对照组;用ELISA法测定MPP患儿急性期、恢复期及对照组儿童血清IL-8、IL-12的水平,用血浆蛋白分析仪速率散射比浊法测定hs-CRP,Ig和C含量。结果:在急性期和恢复期MPP患儿血清IL-12含量明显低于正常对照组(P0.05);而血清IL-8含量在急性期明显高于正常对照组(P0.01)。重症组患儿血清中IL-12明显低于轻症组,而血清中IL-8较轻症组高(P均0.01)。急性期MPP患儿血清IgM,IgG与对照组相比明显升高(P均0.01);而IgA明显降低(P0.05)。急性期MPP患儿hs-CRP、C3、C4与对照组比较显著升高(分别为P0.01、P0.01、P0.05)。重症组患儿血清中IgM,IgG与轻症组相比明显升高(P均0.01);IgA与轻症组相比明显降低(P0.05);重症组患儿血清中hs-CRP、C3、C4与轻症组相比明显升高(P均0.01)。结论:检测相关血清炎性细胞因子对判定MPP患儿的病情和预后有较高的临床应用价值。     

Robust semiparametric microarray normalization and significance analysis

Microarray technology allows the monitoring of expression levels of thousands of genes simultaneously. A semiparametric location and scale model is proposed to model gene expression levels for normalization and significance analysis purposes. Robust estimation based on weighted least absolute deviation regression and significance analysis based on the weighted bootstrap are investigated. The proposed approach naturally combines normalization and significance analysis, and incorporates the variations due to normalization into the significance analysis properly. A small simulation study is used to compare finite sample performance of the proposed approach with alternatives. We also demonstrate the proposed method with a real dataset.     

Some Corrections of the Significance Level in Meta-Analysis

In many applications we obtain test statistics by combining estimates from different experiments or studies. The usual combined estimator of the overall effect in independent studies leads to systematic overestimates of the significance level, see Li, Shi , and Roth (1994). This results in a great number of unjustified significant evidences. By examination of the convexity of composed functions involved and application of higher and inverse moments of the χ² distribution we propose corrections for the estimated standard deviation of the overall effect estimator. Analytical results and simulations show that we improve the estimated significance level in such models.     

Phenotypic Correlation: Its Estimation and Testing Significance

Plant scientists often assess correlation coefficients to develope a selection strategy for better plant type. They generate data on the desired traits on several genotypes grown in a randomized complete block design. Using the data from such experiments, this paper presents the asymptotic standard error of an estimate of phenotypic correlations coefficient and a test of significance. The method is illustrated using data on chickpea crop.     

The Error Rate of Tests for Regression Coincidence and Parallelism Under Unknown Multiplicative Heteroscedasticity

The usual F test of regression coincidence, which is appropriate under a homoscedastic model, is examined under a multiplicatively heteroscedastic model. The departure of the test from its nominal level is slight when the sample of explanatory variables is symmetric, but may be substantially inflated when the sample has positive skew. Conversely, the nominal level may be slightly depressed when the sample has negative skew. The size of the perturbation from the nominal level depends on the degree of heteroscedasticity, however its effect is more pronounced with positively skewed samples. Similar trends are evident for the usual F test of regression parallelism. There is no apparent pattern to the discrepancy of the level of the test with regard to the data which would permit empirical researchers to adjust their results.     

Increased radiation toxicity with germline ATM variant of uncertain clinical significance

BackgroundWhile patients with ataxia telangiectasia are known to have increased radiation sensitivity, patients with germline heterozygous ataxia telangiectasia mutated (ATM) mutations can have widely varying functional and clinical effects, which can make management decisions difficult. With an increased prevalence of gene panel-based testing for breast cancer patients, radiation oncologists are increasingly confronted with patients who carry germline ATM variants of uncertain clinical significance. This study describes the clinical courses and outcomes of 5 breast cancer patients with varying germline heterozygous ATM mutations undergoing radiation therapy at our institution in order to provide additional knowledge of the varying clinical effects to aid future decision making.Case SeriesWe identified 5 patients with breast cancer and varying germline heterozygous ATM mutations treated at the University of North Carolina Hospitals between 2015 and 2017. The median age at breast cancer diagnosis for the patient series was 46. Clinical effects of radiation treatment varied amongst the 5 patients. The one patient with a pathogenic ATM mutation had no increased radiation related toxicity. Of the 4 patients with ATM variants of uncertain significance, one patient had increased radiation sensitivity with Grade 3 dermatitis. All patients have remained recurrence free with a median duration of 18 months.ConclusionOur data illustrates that patients with germline heterozygous ATM mutations can have widely varying clinical effects with radiation therapy. Given the possibility of unpredictable deleterious effects, our study highlights the importance of caution and careful consideration when devising the multi-modality management strategy in these patients.