Inference and Interval Estimation Methods for Indirect Effects With Latent Variable Models

Although much is known about the performance of recent methods for inference and interval estimation for indirect or mediated effects with observed variables, little is known about their performance in latent variable models. This article presents an extensive Monte Carlo study of 11 different leading or popular methods adapted to structural equation models with latent variables. Manipulated variables included sample size, number of indicators per latent variable, internal consistency per set of indicators, and 16 different path combinations between latent variables. Results indicate that some popular or previously recommended methods, such as the bias-corrected bootstrap and asymptotic standard errors had poorly calibrated Type I error and coverage rates in some conditions. Likelihood-based confidence intervals, the distribution of the product method, and the percentile bootstrap emerged as leading methods for both interval estimation and inference, whereas joint significance tests and the partial posterior method performed well for inference.     

回归模型中异方差的检验方法

异方差的存在并不破坏普通最小二乘法估计量的无偏性，但是估计量的方差变大了，由于估计量方差的变大，就使通常假设检验的值不可靠，因此选取适当的异方差的检验方法是极其重要的．     

回归模型中异方差的检验方法

异方差的存在并不破坏普通最小二乘法估计量的无偏性,但是估计量的方差变大了,由于估计量方差的变大,就使通常假设检验的值不可靠,因此选取适当的异方差的检验方法是极其重要的.     

Three-Level Models for Indirect Effects in School- and Class-Randomized Experiments in Education

Due to the clustered nature of field data, multi-level modeling has become commonly used to analyze data arising from educational field experiments. While recent methodological literature has focused on multi-level mediation analysis, relatively little attention has been devoted to mediation analysis when three levels (e.g., student, class, school) are present in a study setting. This article presents analysis models that can be used to test indirect effects in experimental designs having three levels where random assignment is at the third (school) or second (class) level and where the indirect effect may be random. In the presentation, simulated datasets are used to illustrate model specification and results interpretation for hypothetical three-level educational experiments involving mediation and moderation of treatment effects.     

数据的正态性检验方法

在进行数据的统计处理和统计检验时,往往假定数据来自于正态总体,因此对数据进行正态性检验十分必要.本文介绍了描述数据分布的QQ图及适用于小样本情形下数据正态性检验的夏皮罗-威尔克检验法和"Mudholkar"检验法.     

Models and Methods for Urban Power Distribution Network Planning

The models, methods and their application experiences of a practical GIS (geographic information system)-based computer decision-making support system of urban power distribution network planning with seven subsystems, termed CNP, are described. In each subsystem there is at least one or one set of practical mathematical methobs. Some new models and mathematical methods have been introduced. In the development of CNP the idea of cognitive system engineering has been insisted on, which claims that human and computer intelligence should be combined together to solve the complex engineering problems cooperatively. Practical applications have shown that not only the optimal plan can be automatically reached with many complicated factors considered, but also the computation, analysis and graphic drawing burden can be released considerably.     

Monte Carlo Confidence Intervals for Complex Functions of Indirect Effects

One challenge in mediation analysis is to generate a confidence interval (CI) with high coverage and power that maintains a nominal significance level for any well-defined function of indirect and direct effects in the general context of structural equation modeling (SEM). This study discusses a proposed Monte Carlo extension that finds the CIs for any well-defined function of the coefficients of SEM such as the product of k coefficients and the ratio of the contrasts of indirect effects, using the Monte Carlo method. Finally, we conduct a small-scale simulation study to compare CIs produced by the Monte Carlo, nonparametric bootstrap, and asymptotic-delta methods. Based on our simulation study, we recommend researchers use the Monte Carlo method to test a complex function of indirect effects.     

项目反应理论复杂模型发展与参数估计

项目反应数据的建模过程属于项目反应理论范畴,被称为现代测量理论。随着社会测量要求的广度和复杂度的增加,以及测量功能的不断扩展的要求,需要越来越复杂的项目反应模型来完成心理学、教育学、社会学等领域的测量任务。本文就当前较普遍以及发展迅速的项目反应复杂模型,如高阶、多维、多层模型进行论述,并且描述了复杂模型的参数评估技术,结合复杂模型的应用情况,期望本土的测量技术向客观化、尖端化发展。     

高等学校考试新模式的研究与探索

文章客观地分析了传统考试模式的作用和局限性,并围绕考试的功能,从考试目的、内容、方式、机会等方面深入、全面地提出了构建高等学校考试新模式的思路和举措.     

A Comparison of Method Effects in Two Confirmatory Factor Models for Structurally Different Methods

It is well known that measurement error in observable variables induces bias in estimates in standard regression analysis and that structural equation models are a typical solution to this problem. Often, multiple indicator equations are subsumed as part of the structural equation model, allowing for consistent estimation of the relevant regression parameters. In many instances, however, embedding the measurement model into structural equation models is not possible because the model would not be identified. To correct for measurement error one has no other recourse than to provide the exact values of the variances of the measurement error terms of the model, although in practice such variances cannot be ascertained exactly, but only estimated from an independent study. The usual approach so far has been to treat the estimated values of error variances as if they were known exact population values in the subsequent structural equation modeling (SEM) analysis. In this article we show that fixing measurement error variance estimates as if they were true values can make the reported standard errors of the structural parameters of the model smaller than they should be. Inferences about the parameters of interest will be incorrect if the estimated nature of the variances is not taken into account. For general SEM, we derive an explicit expression that provides the terms to be added to the standard errors provided by the standard SEM software that treats the estimated variances as exact population values. Interestingly, we find there is a differential impact of the corrections to be added to the standard errors depending on which parameter of the model is estimated. The theoretical results are illustrated with simulations and also with empirical data on a typical SEM model.     

"结构化学"课程考试方法研究与实践

在＂结构化学＂教学实践中,我们探索了一种＂考试内容突出理论联系实际,采用期中、期末闭卷考试加课程论文作为学生学习总成绩＂的考试评价方式,在闭卷内容方面侧重思路分析,降低数学推导难度,增加应用性题目,并增加课程论文的考试方式,提高学生的学习积极性,培养学生查阅文献、分析问题、综合运用知识解决问题的能力,培养学生的创新能力和综合素质,从而达到提高教学质量的效果.     

Analyzing Different Types of Moderated Method Effects in Confirmatory Factor Models for Structurally Different Methods

An extension of two confirmatory factor models for multitrait-multimethod measurement designs with structurally different methods to the analysis of latent interaction effects is presented: the nonlinear latent difference (NL-LD) model and the nonlinear correlated trait–correlated method-minus-one (NL-CTC[M – 1]) model. Both models are compared with regard to (a) the psychometric definition of the latent variables, (b) the capabilities of explaining latent method effects, and (c) the analysis of latent interaction effects. Using the latent moderated structural equation approach, we show how moderated method effects can be examined in the NL-CTC(M – 1) model. This fine-grained analysis of method effects is not feasible using the classical NL-LD model. We propose an extended version of the NL-LD model, which recovers the results of the NL-CTC(M – 1) model. The different versions of the nonlinear multimethod models are illustrated using real data from a multirater study. Finally, the advantages and challenges of incorporating latent interaction effects in complex CFA–MTMM models are discussed.     

论反求工程在复杂型面产品中的应用

将设计思想与实物原型迅速、直接、精确地转变为可以再加工的CAD模型,分析了反求工程实施中的几个关键技术步骤,即数据采集,测量数据的预处理,曲面重构技术,实体造型技术,并结合复杂型面产品反求的实例,讨论反求工程CAD建模技术与思路。     

工程力学考试方法的探索与实践

一页纸考试是为了适应高校教学改革的需要,对工程力学的考试模式进行的一项有益探索。我们力图通过这样的改革,改变以往教学中一些固有的弊端,培养学生的创新精神和能力,提高大学生的综合素质。     

关于改进商务英语教学评价方法的几点思考

在现有经济环境及商务英语学科快速发展的情况下,商务英语测试评价方法存在滞后问题.通过分析商务英语定位和比较商务英语与普通英语教学大纲及方法的不同,同时参照国外经验,提出改进商务英语教学评价测试方法的初步设想.     

污泥特性测定实验方法的研究

利用我校现有实验设备,设计实验方法测定唐山市污水处理厂污泥的含水率、细菌数、干燥性和发热值等性能,可为进一步进行污泥特性分析和实现污泥资源化奠定基础。     

医药保健品营销模式的比较研究

中国保健品行业近年来迅速发展,传统的营销方式已经不能适应激烈的竞争。与传统营销模式相比,新兴的营销模式具有一定的优越性,如能够提供个性化的服务、销售成本较低、信息沟通具双向性等。     

Testing Predictive Models of Technology Integration in Mexico and the United States

ABSTRACT

Data from Mexico City, Mexico (N = 978) and from Texas, USA (N = 932) were used to test the predictive validity of the teacher professional development component of the Will, Skill, Tool Model of Technology Integration in a cross-cultural context. Structural equation modeling (SEM) was used to test the model. Analyses of these data yielded positive results for the model's validity and reliability, with more than 90% of the variance in classroom technology integration found to be attributable to a linear combination of a teacher's attitude or Will, technology proficiency or Skill, and access to technology Tools. Results also showed a differential effect of predictors on integration, depending on the teacher's stage of technology adoption: At lower stages Tool access appears to be the best predictor; whereas, at higher stages Skill appears to be the best predictor. At the highest stage of adoption Will may replace Skill as the best technology integration predictor. Collective findings regarding the orderings of integration predictors shed light on alternative theoretical views of technology integration. Findings tend to support the view of technology integration as a step-wise, sequential, developmental process, rather than the process of eliminating external and internal barriers that impede the full integration of technology into a classroom teaching/learning environment.     

《现代材料研究方法》课程建设的新思路与新举措

本文介绍了现代材料研究方法课程建设的新思路,以教学目标为导向、以教学内容为载体、以教学组织为纽带、以课程考核为手段,对课程建设的改革提出了切实可行的建议。