The size accuracy of combination tests

Adaptive clinical trials typically involve several independent stages. The P‐values from each stage are synthesized through a so‐called combination function which ensures that the overall test will be valid if the stagewise tests are valid. In practice however, approximate and possibly invalid stagewise tests are used. This paper studies how imperfections of the stagewise tests feed through into the combination test. Several general results are proven including some for discrete models. An approximation formula which directly links the combined size accuracy to the component size accuracy is given. In the wider context of adaptive clinical trials, the main conclusion is that the basic tests used should be size accurate at nominal sizes both much larger and also much smaller than nominal desired size. For binary outcomes, the implication is that the parametric bootstrap should be used.     

Challenges facing foster parent resource workers in Canada

Many different professional staff members in children's services systems interact with foster parents. In Canada, the title “resource worker” is used in many jurisdictions for those who work most directly and closely with licensed foster parents. There is, however, limited research on the experiences of resource workers. In the study, 68 resource workers from 14 agencies within a large metropolitan area in Canada were asked: “What challenges do you face as a foster parent resource worker?” The results were analyzed using concept mapping methodology and resulted in nine concepts: balance diverse stakeholder needs, motivate foster parents, manage dual roles, respond to foster parent misconduct, deal with disagreements, maintain credibility, meet demands of organization, stay up to date on changes, and lack of support. The results were compared and contrasted with the available literature.     

Time matters: the potential and pitfalls of using mixed methods approaches in longitudinal program evaluation

While social programs are often assessed using short-term impact studies, longitudinal designs allow evaluators to capture change over time, identify longer-term outcomes, adapt instruments, and better understand participants in transition. A mixed methods design can be critical in understanding these dynamics; yet there is a lack of literature exploring the practical considerations of planning and conducting qualitative and quantitative data collection and analysis within longitudinal studies. This paper examines two different mixed methods frameworks used in a 5-year evaluation of three youth entrepreneurship programs in East Africa. We show how the evaluation team dealt with unique challenges across methods and over time, and how the design ultimately facilitated a richer understanding of program impacts and processes. Considerations for conducting this type of study are explored, related to the impact of longevity on analysis and research staff. Successfully using a longitudinal mixed methods approach requires researchers to be strategic and reflexive, and work in close collaboration.     

我国保险市场发展的新变化及监管对策分析

文章在概述我国保险市场的基本情况与发展历程基础上,探讨了我国保险市场在保险产品、保险销售模式及保险市场所处大资产管理行业等方面出现的新变化、存在的问题以及各种新变化之间的关系,认为保险业监管应根据保险市场发展的新变化及其存在的问题制定有效的宏观与微观监管策略.     

应急医药物资实物与产能混合储备研究

实物与产能相结合的应急医药物资储备模式是提高应急保障能力、优化资源配置的一种有效途径。为降低应急医药物资储备成本,政府需要对混合储备模式下的储备数量分配进行合理决策。文章在借鉴非线性成本以及应急物资储备研究的基础上,对两种储备方式进行成本分析,构建了实物与产能混合储备模式下的应急医药物资储备模型,给出了不同条件下的最优储备方案,并给出算例进行验证,分析了设备折旧率等因素对最优储备方案以及最小储备成本的影响。结果表明,混合储备模式下合理分配储备数量能够实现应急储备成本最小化,为政府应急医药物资储备工作的开展提供具体的指导依据。     

西方权力制衡理论的历史溯源

西方权力制衡理论萌芽于古希腊古罗马时代。亚里士多德在继承柏拉图思想的基础上提出了不同阶级通过参与城邦政治,并在不同政治机构中参与管理的混合政体思想。后古罗马的波里比阿提出了君主、寡头和民主三位一体的混合政体思想。此后,中世纪以王权和教权为主的二元权力化体系更是界定了政教各自独立、互相平衡、相互制约的控制领域。上述思想观点和实践为近代分权与制衡理论的形成奠定了思想基础。     

保险市场基于保费信号的信号传递博弈模型分析

信号传递博弈是不完全信息动态博弈模型中一类简单、重要的博弈模型,它在经济管理领域内有很多应用。用保费作为信号,建立不完全信息动态的信号博弈模型,分析保险双方的博弈策略选择及其可能达到的均衡,研究表明,博弈模型存在某种形式的精练贝叶斯纳什均衡。     

Semiparametric lack-of-fit tests in an additive hazard regression model

In the semiparametric additive hazard regression model of McKeague and Sasieni (Biometrika 81: 501–514), the hazard contributions of some covariates are allowed to change over time, without parametric restrictions (Aalen model), while the contributions of other covariates are assumed to be constant. In this paper, we develop tests that help to decide which of the covariate contributions indeed change over time. The remaining covariates may be modelled with constant hazard coefficients, thus reducing the number of curves that have to be estimated nonparametrically. Several bootstrap tests are proposed. The behavior of the tests is investigated in a simulation study. In a practical example, the tests consistently identify covariates with constant and with changing hazard contributions.     

Bootstrap estimation of actual significance levels for tests based on estimated nuisance parameters

Often for a non-regular parametric hypothesis, a tractable test statistic involves a nuisance parameter. A common practice is to replace the unknown nuisance parameter by its estimator. The validality of such a replacement can only be justified for an infinite sample in the sense that under appropriate conditions the asymptotic distribution of the statistic under the null hypothesis is unchanged when the nuisance parameter is replaced by its estimator (Crowder M.J. 1990. Biometrika 77: 499–506). We propose a bootstrap method to calibrate the error incurred in the significance level, for finite samples, due to the replacement. Further, we have proved that the bootstrap method provides a more accurate estimator for the unknown actual significance level than the nominal level. Simulations demonstrate the proposed methodology.     

论肖邦叙事曲与混合曲式结构

肖邦在叙事曲中运用混合曲式结构 ,这与他生活在浪漫主义时代强烈地追求音乐上的创新、追求强烈对比的感情表现、追求音乐与其他艺术的综合等相联系 ;又与肖邦独特的艺术个性和音乐审美理想、追求创造新的音乐体裁形式、在传统体裁中采用新的艺术手法相联系 ;更重要的是与具体作品内容的表现需要相联系