Simultaneous non-parametric confidence intervals for survival probabilities from censored data

In medical studies with censored data Kaplan and Meier's product limit estimator has frequent use as the estimate of the survival function. Simultaneous confidence intervals for the survival function at various time points constitute a useful addition to the analysis. This study compares several such methods. We consider in a simulation investigation two whole curve confidence bands and four methods based on the Bonferroni inequality. The results show that three Bonferroni-type methods are essentially equivalent, all being better than the other methods when the number of time points is small (3 or 5).     

Word-specific cortical activity as revealed by the mismatch negativity

Neurophysiological brain activity evoked by individual spoken words and pseudowords was recorded and the mismatch negativity (MMN), an automatic index of experience-dependent auditory memory traces, was calculated. Consistent with earlier reported results, the MMN response to word-final syllables was enhanced compared with that elicited by the same syllables placed in a pseudoword context. Here we now demonstrate that the enhancement of the MMN elicited by two individual words showed different scalp topographies. The early word-specific brain activity is consistent with the assumption that the memory traces activated by individual words are carried by large neuronal ensembles that differ in their distributions over the cortex. Current source estimates localized the between-word differences in the right hemisphere and in parieto-occipital left-hemispheric areas. The differential brain responses to individual words appeared as early as ∼100 ms after the recognition points of the words, suggesting that their specific memory traces become active almost immediately after the information in the acoustic input is sufficient for word identification.     

基于网络的人工髋关节术后评定系统

目的　对人工髋关节置换术后的效果进行评定。方法　采用了三种著名的人工髋关节置换术评定标准 ,利用网络技术和计算机对数据进行采集整理和分析。结果　完成了评定系统的功能 ,能得出正确的结论。结论　采用基于网络的人工髋关节评定系统提高评定的速度和质量 ,其评定结果可方便的进行交流     

诊断试验ROC参数估计双正态样本量估计方法探讨

目的 探讨ROC双正态样本量估计方法的准确性。方法 通过Monte Carlo方法对ROC双正态样本量估计法进行评价与修正。结果 根据模拟试验结果得到双正态样本量估计法的校正公式及修正曲线。结论 采用文中给出的样本量调整方法。可以有效地进行样本量估计。达到诊断试验评价的要求。     

A note on the empirical Bayes heterogeneity variance estimator in meta-analysis

This paper focuses on the empirical Bayes (EB) or Mandel-Paule estimator of the heterogeneity variance in meta-analysis, which was discussed by Morris and proposed in earlier publications by Mandel and Paule in an inter-laboratory context. The relationship of the EB estimator to other heterogeneity variance estimators typically used in meta-analysis is explored, and approximate variance estimators for the EB estimate of the heterogeneity variance are proposed based on the M-estimation method. Statistical inference for the overall treatment effect using the EB estimator and the proposed standard errors is discussed using two example data sets from meta-analysis applications.     

Real-world cost-effectiveness of drug-eluting stents vs. bare-metal stents for coronary heart disease—A five-year follow-up study

Objective

To evaluate the cost-effectiveness of using drugeluting stents (DES) compared to bare-metal stents (BMS) for coronary heart disease (CHD).