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1.
Joerg Evermann 《Structural equation modeling》2013,20(4):677-702
Multiple-group analysis in covariance-based structural equation modeling (SEM) is an important technique to ensure the invariance of latent construct measurements and the validity of theoretical models across different subpopulations. However, not all SEM software packages provide multiple-group analysis capabilities. The sem package for the R system, which holds an important position as the only open-source SEM software, does not currently offer multigroup analysis. This article offers an alternative to true multigroup modeling that is easy to understand and apply in the R software. It is limited, however, by the constraint that groups require equal sample size. 相似文献
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Mike W.-L. Cheung 《Structural equation modeling》2013,20(3):429-454
Multivariate meta-analysis has become increasingly popular in the educational, social, and medical sciences. It is because the outcome measures in a meta-analysis can involve more than one effect size. This article proposes 2 mathematically equivalent models to implement multivariate meta-analysis in structural equation modeling (SEM). Specifically, this article shows how multivariate fixed-, random- and mixed-effects meta-analyses can be formulated as structural equation models. metaSEM (a free R package based on OpenMx) and Mplus are used to implement the proposed procedures. A real data set is used to illustrate the procedures. Formulating multivariate meta-analysis as structural equation models provides many new research opportunities for methodological development in both meta-analysis and SEM. Issues related to and extensions on the SEM-based meta-analysis are discussed. 相似文献
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In this paper,a special-purpose CAD/CAM software package,BliskCad/Cam,based on a commercial CAD/CAM software Unigraphics is developed to reduce difficulties in CNC-EDM of the shrouded turbine blisks.The software package con- sists of five modules such as electrode design,path searching,and machining simulation module.Functions of BliskCad/Cam include parametrical reconstruction of 3-D model of the blisk,intelligent design of complex shaped electrode,automatic gener- ation of NC codes,search of interference-free tool path for multi-axis NC-EDM and machining simulation,etc.Experimental verification is conducted by using BliskCad/Cam and the results show that it satisfies the requirements,and can realize pre- cision machining and reduce accessorial time remarkably. 相似文献
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The aim of this article is to introduce the R package semds for structural equation multidimensional scaling. This methodology combines multidimensional scaling with latent variable features from structural equation modeling and is applicable to asymmetric and three-way input dissimilarity data. This key idea of this approach is that the input data are assumed to be imperfect measurements of a latent symmetric dissimilarity matrix. The parameter estimation is performed via an alternating least squares multidimensional scaling procedure that minimizes the stress. The latent dissimilarities are estimated as factor scores within a structural equation modeling framework. Applications shown in the article involve data associated with the banking crisis and data from avalanche research. The models fitted with the semds package are compared to related methods from multidimensional scaling. The R code to reproduce all the computations is provided in the supplementary materials. 相似文献
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化工原理实验数据处理软件的开发 总被引：6，自引：0，他引：6
以Microsoft Windows操作系统为开发平台，应用Access数据库和Visual Basic 6．0语言，开发了化工原理实验数据处理软件。该软件可运行在Windows 98及以上的操作系统上，界面友好，输入和修改数据简单，能自动绘制实验曲线，并打印实验结果。 相似文献
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This article provides a brief overview of confirmatory tetrad analysis (CTA) and presents a new set of Stata commands for conducting CTA. The tetrad command allows researchers to use model-implied vanishing tetrads to test the overall fit of structural equation models (SEMs) and the relative fit of two SEMs that are tetrad-nested. An extension of the command, tetrad_matrix , allows researchers to conduct CTA using a sample covariance matrix as input rather than relying on raw data. Researchers can also use the tetrad_matrix command to input a polychoric correlation matrix and conduct CTA for SEMs involving dichotomous, ordinal, or censored outcomes. Another extension of the command, tetrad_bootstrap , provides a bootstrapped p value for the chi-square test statistic. With Stata’s recently developed commands for structural equation modeling, researchers can integrate CTA with data preparation, likelihood ratio tests for model fit, and the estimation of model parameters in a single statistical software package. 相似文献
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《Structural equation modeling》2013,20(4):620-641
The Bollen-Stine bootstrap can be used to correct for standard error and fit statistic bias that occurs in structural equation modeling (SEM) applications due to nonnormal data. The purpose of this article is to demonstrate the use of a custom SAS macro program that can be used to implement the Bollen-Stine bootstrap with existing SEM software. Although this article focuses on missing data, the macro can be used with complete data sets as well. A series of heuristic analyses are presented, along with detailed programming instructions for each of the commercial SEM software packages. 相似文献
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In this software review, we provide a brief overview of four different functions to fit a piecewise random-effects model with unknown changepoints (knots). Specifically, the four functions are: FitPMM from the R routine developed by (Zopluoglu, Harring, & Kohli, 2014), PROC NLMIXED from SAS, BayesPGM from the BayesianPGMM package in R developed by (Lock, Kohli, and Bose, 2018), and stancode_randomchangecorr function developed by (Brilleman, Howe, Wolfe, & Tilling, 2017) implemented to interface with Stan from R using the rstan package. We illustrate the estimation of the piecewise random-effects model using each of these functions by using a sample dataset. We provide appropriate commented code for the four functions, and briefly discuss the strengths and weaknesses of each function. 相似文献
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Joyce L. Y. Kwan 《Structural equation modeling》2013,20(2):225-238
In social science research, a common topic in multiple regression analysis is to compare the squared multiple correlation coefficients in different populations. Existing methods based on asymptotic theories (Olkin & Finn, 1995) and bootstrapping (Chan, 2009) are available but these can only handle a 2-group comparison. Another method based on structural equation modeling (SEM) has been proposed recently. However, this method has three disadvantages. First, it requires the user to explicitly specify the sample R2 as a function in terms of the basic SEM model parameters, which is sometimes troublesome and error prone. Second, it requires the specification of nonlinear constraints, which is not available in some popular SEM software programs. Third, it is for a 2-group comparison primarily. In this article, a 2-stage SEM method is proposed as an alternative. Unlike all other existing methods, the proposed method is simple to use, and it does not require any specific programming features such as the specification of nonlinear constraints. More important, the method allows a simultaneous comparison of 3 or more groups. A real example is given to illustrate the proposed method using EQS, a popular SEM software program. 相似文献
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Users assume statistical software packages produce accurate results. In this article, the authors systematically examined Statistical Package for the Social Sciences (SPSS) and Statistical Analysis System (SAS) for 3 analysis of variance (ANOVA) designs, mixed-effects ANOVA, fixed-effects analysis of covariance (ANCOVA), and nested ANOVA. For each model, the authors examined 3 different data sets. With the mixed-effects design, results were always correct for SPSS syntax and SAS syntax. For SPSS point-and-click, the F and p values for the random-effect were always incorrect as the wrong error term is used. With the ANCOVA design, results varied both by software package and by type of sums of squares. With the nested design, the p values for the F and multiple comparison procedure did not agree for the nonnested factor in SPSS point-and-click. Recommendations were made regarding which package to use for each design. 相似文献
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Nigel Oseland Robert Collins John Hegarty 《British journal of educational technology : journal of the Council for Educational Technology》1990,21(3):203-214
The authors argue that there is a need for a microcomputer software authoring package which produces graphics. The novel feature of the Graphics Authoring Package (GAP) which they developed is that it produces Basic code from the user's graphical input. GAP is described together with the results of an evaluation study. The results indicate that the package is easy to use, effective in rapidly producing graphics code and that, in general, it fills a gap in the current range of educational software. 相似文献
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Kilem L. Gwet 《Educational and psychological measurement》2021,81(4):781
Cohen’s kappa coefficient was originally proposed for two raters only, and it later extended to an arbitrarily large number of raters to become what is known as Fleiss’ generalized kappa. Fleiss’ generalized kappa and its large-sample variance are still widely used by researchers and were implemented in several software packages, including, among others, SPSS and the R package “rel.” The purpose of this article is to show that the large-sample variance of Fleiss’ generalized kappa is systematically being misused, is invalid as a precision measure for kappa, and cannot be used for constructing confidence intervals. A general-purpose variance expression is proposed, which can be used in any statistical inference procedure. A Monte-Carlo experiment is presented, showing the validity of the new variance estimation procedure. 相似文献
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Randall E. Schumacker 《Structural equation modeling》2013,20(1):1-2
This article provides a didactic example and application of new developments in structural equation modeling (SEM) that allow for the modeling of multilevel data. Such data often arise naturally from organizational structures in which within‐group units (employees, students, etc.) are observed in larger between‐group units (firms, schools, etc.) The article begins with an overview of the basic ideas of SEM and multilevel linear regression. The synthesis of both methods developed by Muthéin (1994) is then presented in the simple case of a multilevel path analysis model, in which the variations in within‐group level intercepts are modeled as a function of between‐group variables following their own path model. An application motivated by a real problem in the field of education that focuses on validating indicators of the quality of science education in the United States follows. The results show that it is possible to statistically capture the salient complexities of organizations through the application of multilevel SEM. The article concludes with a discussion of the utility of multilevel SEM for organizational studies. 相似文献
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该文选取湖南18个主要产业园区资本、劳动、R&D经费支出为投入要素,应用DEA模型测算全要素投入的综合技术效率及各要素冗余。按照R&D投入强度分类,测度不同R&D投入强度园区的综合技术效率、规模报酬、R&D投入要素冗余情况,分析R&D投入对园区技术效率影响并寻找提升园区技术效率的途径。研究结果表明R&D投入强度与产业园区产出技术效率不具有明显的相关性,R&D投入在劳动密集型产业园区有明显的冗余。 相似文献
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1IntroductionPath planning of autonomous mobile robot is pivotaltechnique for machine intelligence,which ai ms to finda non-collision path frominitial position to objectiveposition according to evaluation functions in anobstacle space[1].It can be described as travelersalesman problem(TSP),a typical combinationopti mization problem,which belongs to the well-known NP-hard opti mization[2].The mathematicaldefinition can be regarded as a mapG=(V,E),where eachlinee∈Ehas a nonnegative powerω(… 相似文献
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计算技术的飞速发展使大规模的显示模拟成为可能，而针对社会和生物现象的模拟，对人类认识自身及其环境具有重大意义，进化是其中最为诱人的领域之一。人的智能是从哪里来的?归根结底是从生物进化中得来的，反映在遗传基因中，脑的结构变化也是通过基因的变化一代代遗传下来。 相似文献
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陈誌敏 《黄冈师范学院学报》2006,26(3):8-10,48
介绍了使用M ap le 9.5求解非常数不变式的A bel型方程的方法.在诸多的应用领域里,不少问题的数学模型常常可用A bel型方程来表示.而非常数不变式(non-constant invariants)的A bel型方程的求解极为困难.用数学软件M ap le求解A bel型方程,是通过解决相关的等价问题,从而求解与可积类(integrab le classes)方程等价的任何一个方程.M ap le的ode-pde程序包具有强大的解算符号微分方程的功能,这是其它数学软件所不能比拟的.它是诸多应用领域内处理A bel型等特殊类型微分方程的十分有效的计算工具. 相似文献
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Il-Hyun Jo 《Asia Pacific Education Review》2009,10(4):525-534
This study investigates the effect of the presentation of social network diagrams on virtual team members’ interaction behavior
via e-mail. E-mail transaction data from 22 software developers in a Korean IT company was analyzed and depicted as diagrams
by social network analysis (SNA), and presented to the members as an intervention. Results showed that the SNA diagrams presented
were effective in increasing the quantity of e-mail transactions among the members and in forming a community of practice.
The findings suggest that SNA diagrams can be used as a cost-effective intervention strategy for virtual team members to actively
share knowledge and collaborate as members of a network of practice. 相似文献