Estimating E-bayesian and hierarchical bayesian of scalar parameter of gompertz distribution under type II censoring schemes based on fuzzy data

In this study, the E-Bayesian and hierarchical Bayesian of the scalar parameter of a Gompertz distribution under Type II censoring schemes were estimated based on fuzzy data under the squared error (SE) loss function and the efficiency of the proposed methods was compared with each other and with the Bayesian estimator using Monte Carlo simulation.     

Heteroscedastic Global Tests that the Regression Parameters for Two or More Independent Groups are Identical

Simulation results are reported on methods that allow both within group and between group heteroscedasticity when testing the hypothesis that independent groups have identical regression parameters. The methods are based on a combination of extant techniques, but their finite-sample properties have not been studied. Included are results on the impact of removing all leverage points or just bad leverage points. The method used to identify leverage points can be important and can improve control over the Type I error probability. Results are illustrated using data from the Well Elderly II study.     

Computing maximum likelihood estimates from type II doubly censored exponential data

It is well-known that, under Type II double censoring, the maximum likelihood (ML) estimators of the location and scale parameters, θ and δ, of a twoparameter exponential distribution are linear functions of the order statistics. In contrast, when θ is known, theML estimator of δ does not admit a closed form expression. It is shown, however, that theML estimator of the scale parameter exists and is unique. Moreover, it has good large-sample properties. In addition, sharp lower and upper bounds for this estimator are provided, which can serve as starting points for iterative interpolation methods such as regula falsi. Explicit expressions for the expected Fisher information and Cramér-Rao lower bound are also derived. In the Bayesian context, assuming an inverted gamma prior on δ, the uniqueness, boundedness and asymptotics of the highest posterior density estimator of δ can be deduced in a similar way. Finally, an illustrative example is included.     

Empirical Non-Parametric Control Charts: Estimation Effects and Corrections

Owing to the extreme quantiles involved, standard control charts are very sensitive to the effects of parameter estimation and non-normality. More general parametric charts have been devised to deal with the latter complication and corrections have been derived to compensate for the estimation step, both under normal and parametric models. The resulting procedures offer a satisfactory solution over a broad range of underlying distributions. However, situations do occur where even such a large model is inadequate and nothing remains but to consider non- parametric charts. In principle, these form ideal solutions, but the problem is that huge sample sizes are required for the estimation step. Otherwise the resulting stochastic error is so large that the chart is very unstable, a disadvantage that seems to outweigh the advantage of avoiding the model error from the parametric case. Here we analyse under what conditions non-parametric charts actually become feasible alternatives for their parametric counterparts. In particular, corrected versions are suggested for which a possible change point is reached at sample sizes that are markedly less huge (but still larger than the customary range). These corrections serve to control the behaviour during in-control (markedly wrong outcomes of the estimates only occur sufficiently rarely). The price for this protection will clearly be some loss of detection power during out-of-control. A change point comes in view as soon as this loss can be made sufficiently small.     

第二次世界大战对世界格局产生的影响

第二次世界大战以雅尔塔体系为基础形成了以美苏两大国为首的世界政治格局,对战后世界政治、经济和国际关系产生了深刻影响。随着两极格局的终结,世界又朝着多极化趋势发展。     

美苏在德国赔偿问题上的矛盾与德国的分裂

德国在二战后被分裂成两个国家,就其外部因素来讲,是由于以美苏为首的大国合作政策在战后逐渐走向对抗并导致冷战的产物,是外部力量施加于德国的结果,而在走向对抗的过程中,美苏在德国赔偿问题上的冲突,是导致德国分裂的一个重要原因。     

基于CiteSpace的非裔未来主义研究与热点分析

作为新兴美学潮流,非裔未来主义提出至今虽不满三十年,但其影响力已辐射了文学、音乐、艺术等众多领域。以WoS和CNKI作为数据库,检索2003年至2021年国内外非裔未来主义研究文献,通过CiteSpace软件,运用知识图谱的分析方法对非裔未来主义研究文献进行共现、共被引与聚类分析。从一系列图谱来看,非裔未来主义研究整体呈现出蓬勃的发展势头;美国,尤其是在南方的佐治亚州已经形成了密切的合作网络;传统问题与现代热点相结合是它的一大特征,其中未来研究与跨传媒性更成为了其中的前沿热点。以知识图谱为分析方式深入探索非裔未来主义的研究领域、研究热点以及研究趋势,能够以更加科学的方式看待非裔未来主义研究,以期能够加深对非裔未来主义的了解并促进其相关研究的发展。     

基于文献计量学的煤工尘肺研究热点分析

探究近20年来我国煤工尘肺研究发展脉络与研究热点。以中国知网(CNKI)收录的2000—2020年1485篇煤工尘肺相关研究文献为数据源,运用CiteSpace对作者、发文机构、关键词绘制可视化知识图谱,同时根据知识图谱回顾相关文献内容。结果显示,煤工尘肺研究自2000年以来发文量呈现先上升后下降的趋势,煤工尘肺相关研究呈现趋冷的状态;研究热点内容为发病机制、治疗、诊断和流行病学研究。基于煤工尘肺研究热点内容及发展脉络,建议应继续加强煤工尘肺发病机制及诊疗措施研究,同时立足于患者的实际生活,致力于全方位全周期地提高患者生活质量。     

Adaptive phase I/II clinical trials for drug combination assessment in oncology using the outcomes of each cycle

Many new anticancer agents can be combined with existing drugs, as combining a number of drugs may be expected to have a better therapeutic effect than monotherapy owing to synergistic effects. Furthermore, to drive drug development and to reduce the associated cost, there has been a growing tendency to combine these as phase I/II trials. With respect to phase I/II oncology trials for the assessment of dose combinations, in the existing methodologies in which efficacy based on tumor response and safety based on toxicity are modeled as binary outcomes, it is not possible to enroll and treat the next cohort of patients unless the best overall response has been determined in the current cohort. Thus, the trial duration might be potentially extended to an unacceptable degree. In this study, we proposed a method that randomizes the next cohort of patients in the phase II part to the dose combination based on the estimated response rate using all the available observed data upon determination of the overall response in the current cohort. We compared the proposed method to the existing method using simulation studies. These demonstrated that the percentage of optimal dose combinations selected in the proposed method is not less than that in the existing method and that the trial duration in the proposed method is shortened compared to that in the existing method. The proposed method meets both ethical and financial requirements, and we believe it has the potential to contribute to expedite drug development.     

Early stopping in seamless phase I/II clinical trials

In recent years, seamless phase I/II clinical trials have drawn much attention, as they consider both toxicity and efficacy endpoints in finding an optimal dose (OD). Engaging an appropriate number of patients in a trial is a challenging task. This paper attempts a dynamic stopping rule to save resources in phase I/II trials. That is, the stopping rule aims to save patients from unnecessary toxic or subtherapeutic doses. We allow a trial to stop early when widths of the confidence intervals for the dose-response parameters become narrower or when the sample size is equal to a predefined size, whichever comes first. The simulation study of dose-response scenarios in various settings demonstrates that the proposed stopping rule can engage an appropriate number of patients. Therefore, we suggest its use in clinical trials.