Instrumental Variables Two-Stage Least Squares (2SLS) vs. Maximum Likelihood Structural Equation Modeling of Causal Effects in Linear Regression Models     

Alberto Maydeu-Olivares  Dexin Shi  Yves Rosseel 《Structural equation modeling》2013,20(6):876-892

In the presence of omitted variables or similar validity threats, regression estimates are biased. Unbiased estimates (the causal effects) can be obtained in large samples by fitting instead the Instrumental Variables Regression (IVR) model. The IVR model can be estimated using structural equation modeling (SEM) software or using Econometric estimators such as two-stage least squares (2SLS). We describe 2SLS using SEM terminology, and report a simulation study in which we generated data according to a regression model in the presence of omitted variables and fitted (a) a regression model using ordinary least squares, (b) an IVR model using maximum likelihood (ML) as implemented in SEM software, and (c) an IVR model using 2SLS. Coverage rates of the causal effect using regression methods are always unacceptably low (often 0). When using the IVR model, accurate coverage is obtained across all conditions when N = 500. Even when the IVR model is misspecified, better coverage than regression is generally obtained. Differences between 2SLS and ML are small and favor 2SLS in small samples (N ≤ 100).  相似文献   

Factor Analysis with Ordinal Indicators: A Monte Carlo Study Comparing DWLS and ULS Estimation     

Carlos G. Forero  Alberto Maydeu-Olivares  David Gallardo-Pujol 《Structural equation modeling》2013,20(4):625-641

Factor analysis models with ordinal indicators are often estimated using a 3-stage procedure where the last stage involves obtaining parameter estimates by least squares from the sample polychoric correlations. A simulation study involving 324 conditions (1,000 replications per condition) was performed to compare the performance of diagonally weighted least squares (DWLS) and unweighted least squares (ULS) in the procedure's third stage. Overall, both methods provided accurate and similar results. However, ULS was found to provide more accurate and less variable parameter estimates, as well as more precise standard errors and better coverage rates. Nevertheless, convergence rates for DWLS are higher. Our recommendation is therefore to use ULS, and, in the case of nonconvergence, to use DWLS, as this method might converge when ULS does not.  相似文献   

Adaptation and evaluation of a learning analytics dashboard to improve academic support at three Latin American universities     

Julio Guerra  Margarita Ortiz-Rojas  Miguel Angel Zúñiga-Prieto  Eliana Scheihing  Alberto Jiménez  Tom Broos  Tinne De Laet  Katrien Verbert 《British journal of educational technology : journal of the Council for Educational Technology》2020,51(4):973-1001

Despite the success of academic advising dashboards in several higher educational institutions (HEI), these dashboards are still under-explored in Latin American HEI's. To close this gap, three different Latin American universities adapted an existing advising dashboard, originally deployed at the KU Leuven to their own context. In all three cases, the context was the main ruling factor to these adaptations. In this paper, we describe these adaptions using a framework that focuses on four different elements of the context: Objectives, Stakeholders, Key moment and Interactions. Evaluation of the adapted dashboards in the three different Latin American universities is conducted through pilots. This evaluation shows the value of the dashboard approach in different contexts in terms of satisfaction, usefulness and impact in academic decision-making and advising tasks. The main contribution of this paper is the systematic reporting of the adaptations to an academic advising dashboard and showing the value of an academic advising dashboard on academic decision-making and advising tasks.  相似文献   

New curve sprint test for soccer players: Reliability and relationship with linear sprint     

Alberto Fílter  Jesús Olivares  Alfredo Santalla  Fabio Y. Nakamura  Irineu Loturco  Bernardo Requena 《Journal of sports sciences》2020,38(11-12):1320-1325

ABSTRACT

The speed performance is involved not only in linear sprints, but also in a wide spectrum of multi-directional movements, such as curve sprinting. Curved sprint can be defined as sprint with gradual and continuous change of direction (COD). Although ~85% of the actions performed at maximum velocity in a professional soccer league are curvilinear sprints, there is not any specific test to assess this ability. This study aimed to analyse the reliability of a new curve sprint test, and compare its results with those obtained by soccer players in linear sprint. Forty experienced soccer players performed 3 attempts of curve sprint (using the penalty arc) to right and left side (17 m), and 3 linear sprints (17 m) in two different days. The ICCs (inter-session reliability) were 0.93 for sprint curve right side (CSRS) and 0.89 for sprint curve left side (CSLS), considered “acceptable”. The CVs (intra-session reliability) were 0.87% in CSRS and 1.15% in CSLS. The coefficient of determination (R²) between linear and curve sprinting was ~35%. The association between curve sides was “very large” (r = 0.878; p < 0.01). In summary, we showed that “curve sprint test” is highly reliable, and that curvilinear and linear sprints are different and independent actions.  相似文献   

Review symposium     

Crain Soudien  Carlos Alberto Torres 《British Journal of Sociology of Education》2008,29(6):719-725

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Making Connections: Learning and Teaching Chemistry in Context     

Donna King  Alberto Bellocchi  Stephen M. Ritchie 《Research in Science Education》2008,38(3):365-384

Even though several studies have reported positive attitudinal outcomes from context-based chemistry programs, methodological obstacles have prevented researchers from comparing satisfactorily the chemistry-learning outcomes between students who experience a context-based program with those who experience a content-driven program. In this narrative inquiry we are able to address the question: how do the recalled experiences of a student and her teacher in context-based and concept-based chemistry programs compare? From the student’s unique perspective of experiencing both programs with the same teacher, we have constructed our collective account around four themes; namely, the extent to which the student makes connections between chemistry concepts and real-world contexts, developing research independence through engaging in extended experimental investigations related to contexts, learning chemistry concepts through contexts, and conceptual sequencing in a context-based program. The student reported real-world connections between chemistry concepts and contexts, found her engagement in the context-driven tasks interesting and productive, and identified connected sequences of concepts across the contexts studied. Despite difficulties for teachers who are required to shift pedagogies, the student’s lived experiences and outcomes from a context-based program provide some encouragement in working through these issues.  相似文献   

Emotional climate of a pre-service science teacher education class in Bhutan     

Sonam Rinchen  Stephen M. Ritchie  Alberto Bellocchi 《Cultural Studies of Science Education》2016,11(3):603-628

This study explored pre-service secondary science teachers’ perceptions of classroom emotional climate in the context of the Bhutanese macro-social policy of Gross National Happiness. Drawing upon sociological perspectives of human emotions and using Interaction Ritual Theory this study investigated how pre-service science teachers may be supported in their professional development. It was a multi-method study involving video and audio recordings of teaching episodes supported by interviews and the researcher’s diary. Students also registered their perceptions of the emotional climate of their classroom at 3-minute intervals using audience response technology. In this way, emotional events were identified for video analysis. The findings of this study highlighted that the activities pre-service teachers engaged in matter to them. Positive emotional climate was identified in activities involving students’ presentations using video clips and models, coteaching, and interactive whole class discussions. Decreases in emotional climate were identified during formal lectures and when unprepared presenters led presentations. Emotions such as frustration and disappointment characterized classes with negative emotional climate. The enabling conditions to sustain a positive emotional climate are identified. Implications for sustaining macro-social policy about Gross National Happiness are considered in light of the climate that develops in science teacher education classes.  相似文献   

茶叶香气成分的研究--乌龙茶与鲜茶香气成分的比较   总被引：9，自引：0，他引：9  

侯冬岩  回瑞华  李铁纯  Alberto  朱永强  刘晓媛 《鞍山师范学院学报》2003,5(6):53-55

报道了用同时蒸馏-萃取装置分别提取乌龙茶与鲜茶香气成分，测得乌龙茶的香气成分含量为3．65％．鲜茶的香气成分含量为2．40%。用GC／MS法分别从乌龙茶与鲜茶香气成分中分离并确定出42种和19种化学成分，并对香气化学成分及含量进行了对比。  相似文献   

The construct validity of Institutional Commitment: A confirmatory factor analysis   总被引：1，自引：0，他引：1  

Amaury Nora  Alberto F. Cabrera 《Research in higher education》1993,34(2):243-262

The present study examined the underlying structure of the variable Institutional Commitment by testing for the convergence, or lack thereof, among different indicators of the construct as represented by three theoretical frameworks (Tinto, 1975, 1987; Bean, 1985; Huselid and Day, 1991). Confirmatory factor analyses revealed that Institutional Commitment could be decomposed into two multiple indicators of the same latent construct: a general factor that groups items related to institutional quality, practical value of an education, utility of an education, fit between student and institution, and loyalty to the institution and another factor represented by items indicating similarity of values (Affinity of Values). Moreover, the study established the predictive validity of each subcomponent on different outcomes related to student persistence. While Institutional Commitment was found to have a significant direct effect on both students' intents to persist and actual persistence behavior, Affinity of Values was not as equally predictive of measures of student retention.Paper presented before the 1991 ASHE Annual Meeting. Boston, Massachusetts.  相似文献   

The Entrepreneurial University: a Fine Answer to a Difficult Problem?     

Virgílio A. Meira Soares  Alberto M. S. C. Amaral 《Higher Education in Europe》1999,24(1):11-21

The recent changes in the relationship between universities and society and the change of attitudes of governments towards higher education institutions are analysed. The different possible reactions of the institutions to the more demanding attitude of society as a whole are discussed. The authors present a critical view of the concept of entrepreneurial universities based on the work of Burton Clark and on the results of the quality audits of the Association of European Universities (CRE), and offer some comments about their applicability and usefulness to European higher education systems.  相似文献