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Construct Validity And Factor Structure Of Student Selection Examination Across SubgroupsArikan, Serkan 01 May 2010 (has links) (PDF)
In developing countries, there is a great demand for university education. In order to select students to universities a standardized test score is used. In Turkey, the Student Selection Test (SST) have important role in admission to universities. However, there is very limited knowledge about what SST mathematics sections actually measures.
The main purpose of the present study is to evaluate the content of the mathematics subtest of the SST in line with mathematical cognitive skills and eventually provide construct related evidence for dimensionality of the test items. Within this framework, it is aimed to cross validate the mathematics subtest across gender groups, school types and two consecutive years. Also relations among mathematical abilities are investigated. This study is first in investigating what is measured by SST Mathematics sections and analyzing construct validity by testing several nested confirmatory factor models.
Comparison of fit indices of five competitive models showed three-factor model has better fit indices in which Basic Computation Ability, Advanced Computation Ability and Geometry Ability is measured. It is concluded that problem solving items are not measuring a different process, but measures some sort of computation ability. There is a problem related to the content of the mathematics subtests of the SST in line with mathematical cognitive skills. Higher order cognitive skills are not measured properly.
Three-factor model is tested about the invariance of the factors across gender, school types and years. It is concluded that invariant factor structure indicates that SST mathematics section is operating similarly for subgroups and years.
The relations among mathematical abilities on three-factor model are investigated by item mapping and structural equation models. It is seen that Basic Computation Ability is a prerequisite to acquire Geometry Ability and Advanced Computation Ability.
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Le déclenchement des avalanches de plaque de neige:<br />De l'approche mécanique à l'approche statistique.Faillettaz, Jerome 27 October 2003 (has links) (PDF)
Ce travail est dédié à l'étude de la rupture du manteau neigeux, conduisant<br />aux avalanches de plaques de neige.<br />La détermination expérimentale de la ténacité de la neige, qui caractérise sa résistance à la propagation d'une fissure, nous a donné des résultats originaux que nous interprétons en tenant compte de la structure particulière de ce matériau.<br />Une étude statistique basée sur les données de La Plagne et de Tignes nous a permis de montrer pour la première fois que les distributions des tailles d'avalanches sont invariantes d'échelle. Aucun modèle ne reproduisant correctement ces statistiques de terrain, nous avons créé un automate cellulaire à deux seuils, piloté en contrainte,<br />qui reproduit le comportement statistique des avalanches mais aussi celui d'autres aléas gravitaires naturels à l'aide du réglage d'un unique paramètre reflétant l'anisotropie de cohésion du matériau. Cette approche peut être considérée comme une alternative<br />à la Criticalité Auto Organisée pour les ruptures gravitaires.
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Parent Involvement in Children's Schooling: An Investigation of Measurement Equivalence across Ethnic GroupsScott, Heather Marie 01 January 2011 (has links)
Epstein et al.'s Theory of Overlapping Spheres of Influence focuses on the interaction and communication, or partnerships, among families, schools, and the community to bring the three closer together. The theory works in conjunction with Epstein's typology of parental involvement, which focuses on six types of involvement that are instrumental to a child's development and his/her school and educational success. These serve as the framework for the study and support the construct of parent's involvement in children's schooling.
The purpose of the current study was to conduct further validation analyses of an inventory designed to measure the construct of parent involvement in their children's schooling through the investigation of measurement invariance to determine if the measurement properties of the inventory varied by race/ethnicity. The study compared the responses of 126 Hispanic parents/guardians with 116 White/non-Hispanic parents/guardians to investigate if these two groups were interpreting the items on the inventory in the same manner. The inventory was administered to a sample of parents/guardians of children in grades 3 through 5 in a local school district.
Findings indicated that the measurement model was misspecified for the White/non-Hispanic group and the Hispanic group and further measurement invariance testing was not conducted. Exploratory factor analyses were conducted in order to investigate which models would best fit the data for both groups. Feedback also was obtained from parents/guardians about the clarity of the inventory, which revealed their confusion with the response scale and the wording of particular items. In addition, they supplied issues or aspects of parent involvement that they found important but missing from the inventory. Results from the psychometric analyses and qualitative feedback indicated that the inventory requires modification and further psychometric investigation. In addition, caution should be exercised for anyone who may be considering utilizing the inventory. Results of the study were interpreted in terms of contributions to the parent involvement literature, as well as recommendations for the improvement of the inventory.
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Translation, Adaptation and Invariance Testing of the Teaching Perspectives Inventory: Comparing Faculty of Malaysia and the United StatesMisieng, Jecky 01 January 2013 (has links)
As a result of growing attention in cross-cultural research, existing measurement instruments developed in one language are being translated and adapted for use in other languages and cultural contexts. The benefits of having the same instrument across cultures can only be realized if the process of translation and adaptation of the measurement instruments produces measurement operations that function similarly across national and cultural boundaries. Producing invariant measurement instruments that assess educational and psychological constructs provide a way of testing the cross-cultural generality of theories that include these constructs.
The major purposes of the study were to translate and adapt the Teaching Perspectives Inventory (Pratt, 1992, 1990) from English to Bahasa Malaysia and compare the psychometric properties of the two versions. The TPI is an instrument developed by Pratt (1992) to ascertain the different conceptions that teachers in higher education have about teaching. The TPI has 45 items, which are divided into five subscales or perspectives referred to as Transmission, Apprenticeship, Developmental, Nurturing, and Social Reform. The first phase of this study translated and adapted the TPI from English into the Malay language of Malaysia or Bahasa Malaysia (BM) using multiple approaches as recommended by the International Test Commission. The approaches used to translate the TPI included forward and back translations, an expert panel review, a pilot study, and cognitive interviews. In the translation process, three initial translators, two back translators, and six expert panel members, including the researcher, came up with a pre-final version of the Malay TPI. During the translation process, two items were found to contain expressions that had no exact equivalent forms in Malay: "virtuoso performers" and "higher ideals." Overall, translating the TPI was a challenging task due to the relatively large number of items in the instrument (45) as well as the complexity and very abstract nature of the constructs. Many of the words and expressions that were brief and concise in the English version became longer and more verbose when translated in Malay. As a result, the translated TPI version appeared longer than the original version. Pilot testing with 25 native speakers of Malay who were faculty members from a number of public universities in Malaysia revealed nine items that needed modification. Cognitive interviewing with five participants from the pilot group revealed one item requiring a change by adding a borrowed word "novis" in brackets next to the Malay expressions, which refers to the original word novice. Due to the confusion with the words referring to `people' in many of the items, additional instructions were added at the beginning of the survey to ensure that the participants responded according to the original intention of the items, which focuses on learners in the faculty's specific classroom context instead of people in the society in general. Following changes to the TPI, this instrument was administered in phase two to a Malaysian sample of 561 faculty.
In the second phase, the study assessed the psychometric properties of the original English version of the TPI with 605 faculty in the U. S. and the translated TPI version of the TPI with the Malaysian sample. The overall internal consistency reliability of both the English (α=.88) and the Malay TPI (α=.93) appeared to be adequate. At the subscale level, the internal consistency reliabilities of all the scales were on the lower side considering the large number of items (9) for each subscale (range = .67 to .83 for the U. S. and .59 to .81 for Malaysia). It was found that three out of the five subscales of the U. S. and Malay TPI had similar alpha reliabilities (Apprenticeship, Nurturing, Social Reform). To assess the cross-cultural factorial validity and measurement invariance of the TPI, confirmatory factor analysis (CFA) was carried out for both the original and the Malay TPI. The sample size for the U. S. group was 605 and the Malay group was 561. The fit for both the U. S. and the Malay correlated five-factor models was less than adequate with the Malay model showing a much worse fit. Correlated errors were found between 64 item pairs in the U. S. model and 389 item pairs in the Malay model. The correlations between the five perspectives in the Malay sample were much higher than those in the U. S. sample suggesting that the perspectives had limited discriminant validity. For example, the correlations between the Nurturing and Developmental perspectives and Nurturing and Social Reform perspectives were 1.0. The inadequate fit of the five-factor correlated model in the Malaysian sample and the minimally acceptable fit in the U. S. sample led to the decision to carry out analyses and compare the groups one subscale at a time. Model modifications for each subscale of both samples were carried out to improve the fit by adding one or more parameters (i.e., correlated errors) for each subscale model to obtain acceptable baseline models. The results of the invariance testing for each subscale did not support the existence of measurement invariance. Overall, the results indicate that the Malay version of the TPI is not ready for use and additional translation and adaptation work is recommended. Future efforts could incorporate improvements in the translation process in the form of recruiting a larger number of certified translators who have in-depth knowledge of teaching in higher education as well as a deep knowledge of the philosophy and purposes behind the TPI. Additional cognitive interviews before and after pretesting and pilot testing of the pre-final version are recommended. Finally, adding a large sample of bilingual educators who would complete both the Malay and English versions of the TPI would provide important psychometric data on the equivalence of the TPI items.
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Propriétés thermiques et superfluides du gaz de Bose à deux dimensionsDesbuquois, Rémi 03 June 2013 (has links) (PDF)
Les propriétés physiques d'un système homogène à l'équilibre thermodynamique sont fortement contraintes par sa dimensionnalité. Le gaz de Bose à deux dimensions est un système particulier de ce point de vue : bien que l'établissement d'un ordre à longue portée soit impossible à température non-nulle, il existe néanmoins une transition de phase vers un état superfluide à basse température. De plus, la dimensionalité réduite du système rend son équation d'état invariante par changement d'échalle pour de faibles interactions atomiques répulsives. Dans ce manuscrit de thèse, nous présentons une étude expérimentale du gaz de Bose à deux dimensions. Nous mesurons son équation d'état de deux methodes différentes, et trouvons un résultat en bon accord avec les prédictions analytiques et numériques. Ces résultats ont également permis de confirmer l'invariance d'échelle du système. De plus, l'une des méthodes ne nécessite qu'un seul paramètre ajustable pour la mesure de l'équation d'état. Nous présentons ensuite une mesure locale du caractère superfluide du gaz. À cet effet, nous avons mis en évidence l'absence de dissipation lors de la perturbation du système par un obstacle en mouvement. Enfin, nous effectuons une analyse des fluctuations du gaz de Bose 2D, qui a permis de confirmer la suppression des fluctuations de densité dans la phase superfluide, ainsi que le rôle dominant joué par les phonons dans les fluctuations de phase.
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Seismic imaging and processing with curveletsHerrmann, Felix J., Hennenfent, Gilles, Moghaddam, Peyman P. January 2007 (has links)
In this paper, we present a nonlinear curvelet-based sparsity-promoting formulation for
three problems in seismic processing and imaging namely, seismic data regularization
from data with large percentages of traces missing; seismic amplitude recovery for subsalt
images obtained by reverse-time migration and primary-multiple separation, given
an inaccurate multiple prediction. We argue why these nonlinear formulations are beneficial.
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Method for Improving the Efficiency of Image Super-Resolution Algorithms Based on Kalman FiltersDobson, William Keith 01 December 2009 (has links)
The Kalman Filter has many applications in control and signal processing but may also be used to reconstruct a higher resolution image from a sequence of lower resolution images (or frames). If the sequence of low resolution frames is recorded by a moving camera or sensor, where the motion can be accurately modeled, then the Kalman filter may be used to update pixels within a higher resolution frame to achieve a more detailed result. This thesis outlines current methods of implementing this algorithm on a scene of interest and introduces possible improvements for the speed and efficiency of this method by use of block operations on the low resolution frames. The effects of noise on camera motion and various blur models are examined using experimental data to illustrate the differences between the methods discussed.
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Dégénérescence et problèmes extrémaux pour les valeurs propres du laplacien sur les surfacesGirouard, Alexandre January 2008 (has links)
Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal
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Autour les relations entre SLE, CLE, champ libre Gaussien, et les conséquencesWu, Hao 26 June 2013 (has links) (PDF)
Cette thèse porte sur les relations entre les processus SLE, les ensembles CLE et le champ libre Gaussien. Dans le chapitre 2, nous donnons une construction des processus SLE(k,r) à partir des boucles des CLE(k) et d'échantillons de restriction chordale. Sheffield et Werner ont prouvé que les CLE(k) peuvent être construits à partir des processus d'exploration symétriques des SLE(k,r).Nous montrons dans le chapitre 3 que la configuration des boucles construites à partir du processus d'exploration asymétrique des SLE(k,k-6) donne la même loi CLE(k). Le processus SLE(4) peut être considéré comme les lignes de niveau du champ libre Gaussien et l'ensemble CLE(4) correspond à la collection des lignes de niveau de ce champ libre Gaussien. Dans la deuxième partie du chapitre 3, nous définissons un paramètre de temps invariant conforme pour chaque boucle appartenant à CLE(4) et nous donnons ensuite dans le chapitre 4 un couplage entre le champ libre Gaussien et l'ensemble CLE(4) à l'aide du paramètre de temps. Les processus SLE(k) peuvent être considérés comme les lignes de flot du champ libre Gaussien. Nous explicitons la dimension de Hausdorff de l'intersection de deux lignes de flot du champ libre Gaussien. Cela nous permet d'obtenir la dimension de l'ensemble des points de coupure et des points doubles de la courbe SLE, voir le chapitre 5. Dans le chapitre 6, nous définissons la mesure de restriction radiale, prouvons la caractérisation de ces mesures, et montrons la condition nécessaire et suffisante de l'existence des mesures de restriction radiale.
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Chaos multiplicatif Gaussien, matrices aléatoires et applicationsAllez, Romain 23 November 2012 (has links) (PDF)
Dans ce travail, nous nous sommes intéressés d'une part à la théorie du chaos multiplicatif Gaussien introduite par Kahane en 1985 et d'autre part à la théorie des matrices aléatoires dont les pionniers sont Wigner, Wishart et Dyson. La première partie de ce manuscrit contient une brève introduction à ces deux théories ainsi que les contributions personnelles de ce manuscrit expliquées rapidement. Les parties suivantes contiennent les textes des articles publiés [1], [2], [3], [4], [5] et pré-publiés [6], [7], [8] sur ces résultats dans lesquels le lecteur pourra trouver des développements plus détaillés
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