Examining the Rule of Thumb of Not Using Multilevel Modeling: The “Design Effect Smaller Than Two” Rule

Educational researchers commonly use the rule of thumb of “design effect smaller than 2” as the justification of not accounting for the multilevel or clustered structure in their data. The rule, however, has not yet been systematically studied in previous research. In the present study, we generated data from three different models (which differ in the location of the clustering effect). With a 3 (design effect) × 5 (cluster size) × 4 (number of clusters) Monte Carlo simulation study we found that the rule should not be applied when researchers: (a) are interested in the effects of higher-level predictors, or (b) have a cluster size less than 10. Implications of the findings and limitations of the study are discussed.     

Reexamining the Impact of Nonnormality in Two-Group Comparison Procedures

The authors performed a Monte Carlo simulation to empirically investigate the robustness and power of 4 methods in testing mean differences for 2 independent groups under conditions in which 2 populations may not demonstrate the same pattern of nonnormality. The approaches considered were the t test, Wilcoxon rank-sum test, Welch-James test with trimmed means and Winsorized variances, and a nonparametric bootstrap test. Results showed that the Wilcoxon rank-sum test and Welch-James test with trimmed means and Winsorized variances were not robust in terms of type I error control when the 2 populations showed different patterns of nonnormality. The nonparametric bootstrap test provided power advantages over the t test. The authors discuss other results from the simulation study and provide recommendations.     

高职行业英语课程开发探究

目前高职院校在英语教学方面存在着亟需解决的问题,行业英语能有效地弥补基础英语与专业英语之间的差距。在对课程性质、学生情况、调研情况等综合因素分析的基础上,提出高职行业英语课程的目标设置,并从四个方面,即课程设置、教材开发、场景模拟和教师队伍建设四个方面对高职行业英语课程进行开发。     

我国冰雪旅游发展的系统动力学仿真研究

目的:预测分析冰雪旅游业下一阶段的发展潜力,以此来规避风险、降低损失,实现冰雪旅游业发展的最大化效益。方法:利用系统动力学方法,借助Vensim PLE软件,构建我国冰雪旅游发展的系统动力学模型,仿真分析子系统中各影响因素之间的相互作用关系并探究冰雪旅游发展的动力机制。结果:增加潜在旅游者数量、加大宣传力度、加强基础设施建设投入金额、加大投资额度等发展策略均能不同程度地促进冰雪旅游发展;增加潜在旅游者数量、加大投资额度发展策略是实现2022年“三亿人参与冰雪运动”总目标的有力保证;以2022年为时间节点,2020—2022年增加潜在旅游消费者是首选的发展策略;2022年以后加强冰雪旅游投资额度是首选的发展策略。结论:未来冰雪旅游的发展可以通过控制潜在旅游者数量、加大投资额度及其相关因素,有效实现冰雪旅游的可持续发展。     

Learning statistics with interactive pictures using R Shiny: Generally preferred,but not generally advantageous

Constructing interactive web apps has become more accessible for instructors, for example, by using the R package Shiny. Here we explored learners' preferences and the efficiency of interactive simulations versus static pictures in acquiring statistics knowledge of Cohen's d and standard normal distribution. Results revealed that students' spontaneous interaction with pictures was infrequent (pilot study, N = 26). While prompts (Exp. 1, N = 152) effectively ensured the manipulation of simulations, student exposure to interactive simulations led to longer learning times though similar test performance compared with student exposure to static pictures. Multiple interactive representations led to lower test performance than single interactive and static representations (Exp. 2, N = 117). Though no advantage was gained regarding learning outcomes, participants preferred the interactive variant (Exp. 3, N = 119). Taken together, this study demonstrates that the superiority of interactive pictures cannot be assumed to hold in general. Further work should evaluate how mental model construction can be effectively scaffolded by interactive simulations.     

大型虚拟仿真训练中心的建设与研究

虚拟仿真技术可以模拟现实世界的真实系统,学生可以进行机械设计、零部件建模与整体装配、艺术设计与建筑设计,可以虚拟特殊领域的实验,如化工爆破、电力系统的极限运行状态等现实难于进行的实验操作,有助于培养学生的创新实践能力,同时具有成本低、效率高、安全性好的特点。     

基于Matlab的夫兰克-赫兹实验的计算机模拟

夫兰克-赫兹实验是至今探索原子结构的重要手段之一。本文基于Matlab模拟夫兰克-赫兹实验,研究阴极射线管电压和拒斥电压对电流曲线的影响,并分析了其原因。     

“三期”叠加背景下区域发展对科技创新效能响应的SD情景仿真*

首先对2011年全国科技创新效能进行了评估,得出虽然作为我国科技大省之一的陕西省的科技资源投入相比不小,但其科技创新效能相比全国其他省区并没有太大优势,分析其原因在于科技成果转化率不高所致;进而通过系统动力学建模原理,构建陕西经济发展的SD模型,并设定三种不同的科技成果转化率情景方案,并对选取的观测变量进行仿真,得出未来陕西省科技成果转化率需要至少提升至25%以上方能实现陕西“十二五”规划中部分约束性目标;并就如何提升陕西科技成果转化效率提出建立以政府需求和市场需求相结合的研发模式、构建产学研用协同创新的产业化研发平台、建设科技创新企业混合产权制度和完善公平的市场竞争环境三项对策建议。     

网络面偏移量递阶控制草地视景生成仿真

传统方法中采用二维层状纹理绘制方法生成草地动态视景,当草地出现层阶地势是草地视景的边界接缝处理不够理想,轮廓区域出现视觉的跳变。引入竖直纹理切片,对草地的视景生成进行优化,提出一种基于网络面偏移量递阶控制模型的草地视景生成算法,首先进行草地三维体纹理构造,采用高斯核平滑处理算法处理草叶数据,在草地动态模拟中,设计网络面偏移量递阶控制算法,根据草叶弯曲程度和地势平坦程度而自动进行网络面的层数调整的动态非均匀层递阶控制,消除视觉跳变现象。基于GPU可编程功能,实现不同大规模地形下风场作用下的草地动态视景生成模拟仿真。仿真实验表明,采用该方法进行草地动态实时模拟,能真实动态地模拟风力等作用下草地起伏视景,绘制执行效率和生动逼真性都优越于传统方法。