Power and Sample Size for Fixed-Effects Inference in Reversible Linear Mixed Models

ABSTRACT

Despite the popularity of the general linear mixed model for data analysis, power and sample size methods and software are not generally available for commonly used test statistics and reference distributions. Statisticians resort to simulations with homegrown and uncertified programs or rough approximations which are misaligned with the data analysis. For a wide range of designs with longitudinal and clustering features, we provide accurate power and sample size approximations for inference about fixed effects in the linear models we call reversible. We show that under widely applicable conditions, the general linear mixed-model Wald test has noncentral distributions equivalent to well-studied multivariate tests. In turn, exact and approximate power and sample size results for the multivariate Hotelling–Lawley test provide exact and approximate power and sample size results for the mixed-model Wald test. The calculations are easily computed with a free, open-source product that requires only a web browser to use. Commercial software can be used for a smaller range of reversible models. Simple approximations allow accounting for modest amounts of missing data. A real-world example illustrates the methods. Sample size results are presented for a multicenter study on pregnancy. The proposed study, an extension of a funded project, has clustering within clinic. Exchangeability among the participants allows averaging across them to remove the clustering structure. The resulting simplified design is a single-level longitudinal study. Multivariate methods for power provide an approximate sample size. All proofs and inputs for the example are in the supplementary materials (available online).     

Strategic flexibility analysis of HRD research and practice post COVID-19 pandemic

ABSTRACT

While governments, intergovernmental organizations, non-profits, corporations are all aware that disruptions through pandemics and other natural bio-disasters like the COVID-19 pandemic can happen, barely are we proactive about them. Instead, we are always reactive. In a virtual Town Hall meeting of the Academy of Human Resource Development (AHRD) held on 9 April 2020, on the theme ‘How is the pandemic a game-changer for HRD?,’ the President of AHRD, Laura Bierema, challenged HRD scholars to determine the possible futures of HRD scholarship post-COVID-19 Pandemic. This article proposes the use of the Strategic Flexibility Framework (SFF) to determine the possible futures of HRD post-COVID-19 pandemic. I first discuss the SFF as a scenario planning and analysis tool. I then developed four scenarios of possible futures for HRD Research and Practice post-COVID-19 pandemic. These scenarios include the ‘Meaning of work,’ ‘Leadership,’ ‘Contactless Commerce & Education,’ and ‘Volunteerism.’ I conclude by discussing the important opportunities that can serve as intervention points for post-COVID-19 HRD theory, research, and practice.     

试论教育战略及教育战略学的建设

教育战略是教育整体具有全局性、远见性、主导性和决定性、实效性的行动纲领与策略体系。该文首次对教育战略本体进行"元研究"意义上的讨论,并论及教育战略学的建设问题。     

森林生态服务供给的政策手段研究

通过比较法制、财经、市场等政策手段的优缺点,指出政府实施有利于环境的森林政策,不但要根据具体对象选择恰当的政策手段,而且要重视不同手段的平衡使用。并以范例证明了"政府主导、市场带动、群众参与"的森林环境政策模式。     

文艺传播亟须强化人文理性精神

目前我国的文艺传播 ,亟须在强化法律建设和法治精神的前提下 ,强化人文理性精神 ,以期在新的传播环境中 ,尽快克服靠集中整治解决问题的“路径依赖” ,摆脱文艺传媒发生重要异变 ,而新的约束机制却匮乏和乏力带来的监管困境。同时 ,整合壮大正派的文艺批评阵营 ,倡导理性务实的文艺批评 ,以削弱进而消除各种“炒作”加剧的浮躁、混乱现象 ,促进经济社会和人的全面发展。     

航空公司战略联盟的经济动因分析

本文从经济学角度讨论航空公司战略联盟的动因,认为航空公司联盟旨在节约生产成本和交易成本。本文分析了航空公司战略联盟的网络经济性,基于交易成本经济学分析了航空公司联盟相对于市场而言对交易成本的节约。本文提出修正的威廉姆森启发式模型,并将其应用于分析和比较在国际航空运输市场中完整航空客运产品的实现方式。     

网络文化对高校“两课”教育的挑战及应对

网络文化作为一种新的文化形态,远未成熟,但它带给社会政治、经济、文化等各方面的影响和冲击却是不容忽视的.面对机遇与挑战,只有正确认识和把握网络技术和网络文化对青年大学生的影响问题,才能找到应对措施,进一步展开"两课"教育.     

毛泽东与邓小平“共同富裕”措施之比较

“共同富裕”是毛泽东、邓小平共同的追求。由于他们所处的时代条件和思考问题的出发点不同,对实现共同富裕的前提条件、物质保证、力量源泉和分配原则等方面所采取的措施存在异同,结果人民在追求共同富裕的道路上前后出现“普遍贫穷”与逐步摆脱贫穷并走上小康之差别。邓小平的共同富裕思想对我们今天全面建设小康社会具有重要指导意义。     

中国抗战为何未出现战略反攻阶段

中国人民经八年抗战,最终把日本军队赶出中国,但中国战场并未如人们预期的那样出现一个"战略反攻阶段",而是在全世界反法西斯战争全面胜利的形势下结束了战争。这种局面的出现,既体现了中国抗战不同于欧洲及太平洋战场的特点,也反映出太平洋战争爆发后,中国战场在世界反法西斯战争中所肩负的特殊任务及其作用。但这并不能由此否定中国人民用自己的力量取得了抗日战争的伟大胜利和对世界反法西斯战争的巨大贡献。     

战略联盟:产业创新中的机会开发者

产业创新战略已经成为知识经济背景下的企业战略选择。机会开发是产业创新战略的第一步。战略联盟这种新型组织形式和竞争形态具有使企业扩大搜寻范围,在现存或其他产业和技术领域中开发新机会的功能。联盟能够随着环境的变化而不断地改变形体、吐纳养分和进化演变,通过不断地认识和开发新机会,联盟为企业增加财富创造力和保持持续竞争优势。建立"潜在机会评估框架"能很好地演示这一过程。