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91.
章朝庆 《江苏广播电视大学学报》2003,14(3):46-48
“不变性”是线性代数中的重要思想方法,它主要反映矩阵在某种条件下的秩数不变、特征值不变及正定性不变等方面。以初等变换为首选的变换方法能够充分认识矩阵或线性方程组相关变换的本质。 相似文献
92.
基于跨时测量恒等视角与知识图谱分析,文章对我国教育技术学较常探讨的变量"自我效能"量表进行了工具检测,并以四川省某小学三年级的197名学生为被试,前后测时间间隔为6个月。文章采用结构方程模型的跨时测量恒等检验程序,依序针对不同恒等程度的模型进行比较,结果发现:数学自我效能量表不符合完全的度量恒等,放宽两道题项的参数限制后可达到部分的纯量恒等,但仍不及严格恒等的要求;跨时测量恒等性的结果会影响配对样本t检验的结论。基于此,文章提出建议:为了提升实验的内在效度,较长时间的实验研究应纳入工具的跨时测量恒等性检验。 相似文献
93.
讨论了梯度特征向量法的四个性质,即相容性、协调性、置换不变性、对称性,并且用梯度特征向量法推导和证明了判断矩阵在新元素导入下强保序的充要条件． 相似文献
94.
《European Journal of Sport Science》2013,13(1):35-45
Abstract The aim of the present study was to examine the sensitivity of the Soccer Defending Skill Scale (SDSS) using multiple-group analysis and a structured mean model. The data were 469 defending performances in the finals of the FIFA World Cup Korea/Japan 2002TM, which were measured as distances, angles between attackers and defenders, and the number of players using 6-point interval scales. The results of multiple-group analysis indicated that the model, which had factor loading, intercept and factor correlation, and F3/F4/F6 variances invariant across Brazil and Germany, represented the best fit to the data (e.g. Tucker-Lewis index = 1.001, confirmatory fit index = 1.000, root mean square error of approximation = 0.000). Furthermore, the latent mean model comparison between teams revealed significant differences in latent mean with respect to “defence to attackers without the ball” (Brazil < Germany). We conclude that our results provide strong support for the sensitivity of the SDSS. 相似文献
95.
Eun Sook Kim Seang-Hwane Joo Philseok Lee Yan Wang Stephen Stark 《Structural equation modeling》2016,23(6):870-887
This simulation study examines the efficacy of multilevel factor mixture modeling (ML FMM) for measurement invariance testing across unobserved groups when the groups are at the between level of multilevel data. To this end, latent classes are generated with class-specific item parameters (i.e., factor loading and intercept) across the between-level classes. The efficacy of ML FMM is evaluated in terms of class enumeration, class assignment, and the detection of noninvariance. Various classification criteria such as Akaike’s information criterion, Bayesian information criterion, and bootstrap likelihood ratio tests are examined for the correct enumeration of between-level latent classes. For the detection of measurement noninvariance, free and constrained baseline approaches are compared with respect to true positive and false positive rates. This study evidences the adequacy of ML FMM. However, its performance heavily depends on the simulation factors such as the classification criteria, sample size, and the magnitude of noninvariance. Practical guidelines for applied researchers are provided. 相似文献
96.
The VIA Classification of Strengths and Virtues attempts to provide a comprehensive model of character based on 24 character strengths. The present study is the largest study to date exploring the structure of the 24 strengths in youth. One sample (N = 23,850) completed the VIA-Youth, a teen measure of the VIA Classification. Based on a random subsample, it was determined the data were best modeled using four factors. The remainder of the sample was used to demonstrate measurement invariance for the four-factor model across ages 10–17 and country. Comparison with 471 English academy school students who completed two alternate measures of the VIA Classification also demonstrated measurement invariance. The results suggest a four-factor model that includes two primarily interpersonal factors, one reflecting general engagement, the second other-directedness. Other factors involved intellectual and self-control strengths. Implications for the understanding of character strengths in youth versus adults are discussed. 相似文献
97.
崔万臣 《唐山师范学院学报》2000,(2)
极限保号性是极限理论中的重要性质,对这一性质的教与学,本文提出比现行教材更全面,更简捷明确,更便于学习者掌握其实质的阐述方法。 相似文献
98.
Alex C. Garn E. Kipling Webster 《Measurement in physical education and exercise science》2018,22(3):200-212
The Test of Gross Motor Development – Second Edition (TGMD-2) is a widely used evaluation tool of children’s fundamental motor skills (FMS). This study illustrates how exploratory structural equation modeling (ESEM) addresses current limitations associated with TGMD-2 factor structure. Using the normative dataset from the TGMD-2 manual, we test alternative measurement models using ESEM and confirmatory factor analysis (CFA) and assess measurement invariance between boys and girls and across age. Findings highlight complexity and poor discriminant validity in the two-factor solution that is accentuated when relying on CFA independent clusters assumption. Results also demonstrate differential item functioning (DIF) across age for three of the 12 TGMD-2 indicators. Taken together, this study provides valuable information on the need to reevaluate the TGMD-2 factor structure and can guide revisions for the third edition of the TGMD. 相似文献
99.
Within mathematics education research, there has been a strong focus on students’ understanding of mathematical equivalence because of its key role in the development of mathematics skills. One of the most frequently used tools to assess students’ understanding of equivalence has been the Mathematical Equivalence Assessment (MEA) (Rittle-Johnson et al., 2011). In this study, we investigate for the first time the cross-cultural measurement invariance of an adaptation of the MEA. This included a sample (N = 2760) of students aged 8–12 years old from China, England, New Zealand, South Korea, Turkey, and US to examine whether the same construct is being measured across all countries. Configural and partial scalar invariance was established for a two-factor, 11-item version of the adapted MEA. There were significant mean differences across countries, with students from China performing better and students from New Zealand performing worse than the rest of the sample. 相似文献
100.
Haotian Wu Guo Dong Bai Shuo Liu Lianlin Li Xiang Wan Qiang Cheng Tie Jun Cui 《国家科学评论(英文版)》2020,7(3):561
We propose a theory to characterize the information and information processing abilities of metasurfaces, and demonstrate the relation between the information of the metasurface and its radiation pattern in the far-field region. By incorporating a general aperture model with uncertainty relation in L2-space, we propose a theory to predict the upper bound of information contained in the radiation pattern of a metasurface, and reveal the theoretical upper limit of orthogonal radiation states. The proposed theory also provides guidance for inverse design of the metasurface with respect to given functionalities. Through investigation of the information of disordered-phase modulated metasurfaces, we find the information invariance (1−γ, where γ is Euler''s constant) of chaotic radiation patterns. That is to say, the information of the disordered-phase modulated radiation patterns is always equal to 1−γ, regardless of variations in size, the number of elements and the phase pattern of metasurface. This value might be the lower bound of radiation-pattern information of the metasurface, which can provide a theoretical limit for information modulation applications, including computational imaging, stealth technologies and wireless communications. 相似文献