The Misspecification of the Covariance Structures in Multilevel Models for Single-Case Data: A Monte Carlo Simulation Study     

Mariola Moeyaert  Maaike Ugille  John M. Ferron  S. Natasha Beretvas  Wim Van den Noortgate 《Journal of Experimental Education》2016,84(3):473-509

The impact of misspecifying covariance matrices at the second and third levels of the three-level model is evaluated. Results indicate that ignoring existing covariance has no effect on the treatment effect estimate. In addition, the between-case variance estimates are unbiased when covariance is either modeled or ignored. If the research interest lies in the between-study variance estimate, including at least 30 studies is warranted. Modeling covariance does not result in less biased between-study variance estimates as the between-study covariance estimate is biased. When the research interest lies in the between-case covariance, the model including covariance results in unbiased between-case variance estimates. The three-level model appears to be less appropriate for estimating between-study variance if fewer than 30 studies are included.  相似文献   

Comparing Student Performance and Growth in 2- and 4-Year Institutions     

Strauss  Linda C.  Volkwein  J. Fredericks 《Research in higher education》2002,43(2):133-161

This study examines the organizational characteristics of 51 higher education institutions in relationship to student performance and growth. The study first finds that organizational measures of mission, size, wealth, complexity, and selectivity are statistically represented by the 2-year versus 4-year college mission. Findings indicate that 2-year and 4-year campuses indeed do exert significantly different influences on undergraduate GPA and self-reported intellectual growth. Next, the study uses both OLS regression and HLM to examine these influences. High school percentile rank and college classroom experiences are better predictors of Cum GPA at 4-year institutions, while student effort is a better predictor of GPA at 2-year institutions. Whereas the most important predictors of Cum GPA include precollege measures such as high school percentile rank and SAT score, the most influential predictors of student intellectual growth are campus experiences including classroom vitality, peer support, student effort, commitment, and involvement. Controlling for all other variables, students at 2-year institutions receive higher grades, and students at 4-year campuses experience more growth.  相似文献   

Modeling the influences of upper-elementary school students’ digital reading literacy,socioeconomic factors,and self-regulated learning strategies     

Shin-Feng Chen 《Research in Science & Technological Education》2017,35(3):330-348

Background: Reading is an interactive and constructive process of making meaning by engaging a variety of materials and sources and by participating in reading communities at school or in daily life.

Aim: The purpose of this study was to explore the factors affecting digital reading literacy among upper-elementary school students.

Method: A 3-stage stratified cluster sampling was implemented that resulted in a sample of 592 upper-elementary students from 29 classes in 7 schools. Self-Regulated Learning Strategies Assessment (S-RLSA), Digital Reading Literacy Assessment (DRLA), and student reports of their parents’ education backgrounds were used to collect data on the outcome and predictor variables. Interpretation of these data involved two highly regarded statistical techniques. First, structural equation modeling was used to explore relationships amongst the constructs. Second, multi-group invariance (MI) analyses were used to assess the influence of parental education and self-regulated learning strategies on students’ digital reading literacy.

Results: Enriching students’ family learning resources and strengthening their self-regulated learning abilities could have very important influences on promoting upper-elementary school students' digital reading literacy -webpage information retrieval, reading and communication abilities.

Conclusions: This study also provides information on how teachers can address student resources to improve digital reading literacy and self-regulated strategies.  相似文献   

BIM在建设工程项目中的创新价值初探     

刘慧  王孟钧  Miroslaw J. Skibniewski  郑俊巍 《科技管理研究》2016,(8):194-200

对BIM国际前沿文献进行跟踪研究,梳理BIM在建设工程项目中的主要应用模式。在分析建设工程创新特性的基础上,指出BIM为建设工程项目各参与组织构建了合作创新的工作环境。依据建设工程创新类别,分析BIM应用模式的创新定位,探索BIM在建设工程创新中的价值。  相似文献   

视频信息检索技术的发展及应用   总被引：4，自引：0，他引：4  

陈次白  季春  颜端武 《情报理论与实践》2005,28(5):542-545

今天视频检索的重要性已经越来越被人们所重视。本文总结了视频信息检索技术的发展历程、技术特点及国内外应用现状，最后预测了未来的发展趋势。  相似文献   

沉积微相约束条件下的随机地质建模方法及应用研究   总被引：12，自引：0，他引：12  

王端平  杨耀忠  龚蔚青  柳世成  王延忠  于金标 《科技通报》2004,20(2):121-126

以地质建模为主要研究对象,根据油田开发地质研究需要完善的方法技术,以建模方法研究为基础,进行了沉积微相约束地质建模综合研究.在分析目前国内外研究现状的基础上,针对我国开发地质研究工作的特点,提出根据测井解释成果,应用随机模拟的方法定量地开展沉积微相研究.应用沉积微相研究成果约束测井储层参数的分布,形成油藏数值模拟研究所需要的准确的储层三维地质模型,解决了常规油田开发地质研究过程中沉积相研究成果与储层参数分布无法有效结合的缺陷.应用与该方法相适应的IRMS软件成功实现了山东胜利油区孤东油田第七开发区西部上第三系馆陶组油藏精确的沉积微相模型,由此微相约束形成的油藏储层三维地质模型数据体直接应用于油藏数值模拟研究,应用效果及现场实施的效果良好.  相似文献   

Application of machine learning techniques to assess the trends and alignment of the funded research output     

《Journal of Informetrics》2020,14(2):101018

Research and development activities are regarded as one of the most influencing factors of the future of a country. Large investments in research can yield a tremendous outcome in terms of a country’s overall wealth and strength. However, public financial resources of countries are often limited which calls for a wise and targeted investment. Scientific publications are considered as one of the main outputs of research investment. Although the general trend of scientific publications is increasing, a detailed analysis is required to monitor the research trends and assess whether they are in line with the top research priorities of the country. Such focused monitoring can shed light on scientific activities evolution as well as the formation of new research areas, thus helping governments to adjust priorities, if required. But monitoring the output of the funded research manually is not only very expensive and difficult, it is also subjective. Using structural topic models, in this paper we evaluated the trends in academic research performed by federally funded Canadian researchers during the time-frame of 2000–2018, covering more than 140,000 research publications. The proposed approach makes it possible to objectively and systematically monitor research projects, or any other set of documents related to research activities such as funding proposals, at large-scale. Our results confirm the accordance between the performed federally funded research projects and the top research priorities of Canada.  相似文献   

我国科技期刊视频摘要的社交化传播及其优化策略研究     

李杨  林芝 《编辑学报》2023,(4):434-438

通过对社交媒体平台上科技期刊视频摘要的实践进行梳理,总结我国科技期刊视频摘要社交化传播现状,并提出优化策略。在微信平台搜索“视频摘要”,并按一定标准筛选,对最终查找到的30本科技期刊的相关数据进行统计和分析。结果显示,社交平台上科技期刊论文视频摘要的识别检索存在一定困难,明确标注使用“视频摘要”的较少,不同科技期刊在公众号或视频号上的视频摘要传播效果存在差异。总体而言,我国科技期刊视频摘要相关实践已取得一定成效,但也存在一定问题,需进一步规范使用与清晰标注,强化社交化、多模态化与有策略的传播,以提升传播效果,并拓展学术成果传播的多样可能。  相似文献   

微电网的仿真与实验系统Ⅱ—建模仿真及实现     

解大  顾羽洁  徐涛  艾芊  张明  金之检 《实验室研究与探索》2011,30(10):53-58,145

文中基于美国西部联合电网(Western Systems Coordinating Council,WSCC)3机9节点系统,建立了1个带有逆变并网接口的输电网模型,并利用逆变并网接口模型模拟了微电网与上级输电网的连接,对微电网对上级电网电压与频率的支持情况进行了数字仿真。仿真结果表明在上级输电网的有功与无功负荷发生突变时,微电网的接入使上级输电系统的有功与无功功率能够实现就地平衡,并保持系统频率与电压幅值的稳定。整个微电网系统仿真环境设定均按照实验室所能达到的低电压低容量条件下完成。文中所有仿真算法及结果均在PSCAD/EMTDC软件环境及动态模拟实验室中得到验证。  相似文献   

旋风除尘器操作试验台的建模设计     

薛来  华张国 《实验室研究与探索》2011,30(9):39-41

设计制作了"旋风除尘器操作试验台",该装置能调节风量、进灰量等各种试验参数,可观察除尘器内部的气流运动、除尘效果和灰分收集情况,为"大气污染控制工程"和"锅炉原理"等课程的教学提供了实验手段。通过对旋风除尘器的工作原理及结构进行分析,建立以除尘效率、压力损失为目标函数的双目标数学模型。考虑了设计变量和约束条件后,经过优化设计,寻找出旋风除尘器的最优化结构参数,绘制试验平台结构图,并制作了旋风除尘器操作试验台。  相似文献