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Factors that Influence Cross-validation of Hierarchical Linear ModelsWidman, Tracy 07 May 2011 (has links)
While use of hierarchical linear modeling (HLM) to predict an outcome is reasonable and desirable, employing the model for prediction without first establishing the model’s predictive validity is ill-advised. Estimating the predictive validity of a regression model by cross-validation has been thoroughly researched, but there is a dearth of research investigating the cross-validation of hierarchical linear models. One of the major obstacles in cross-validating HLM is the lack of a measure of explained variance similar to the squared multiple correlation coefficient in regression analysis.
The purpose of this Monte Carlo simulation study is to explore the impact of sample size, centering, and predictor-criterion correlation magnitudes on potential cross-validation measurements for hierarchical linear modeling. This study considered the impact of 64 simulated conditions across three explained variance approaches: Raudenbush and Bryk’s (2002) proportional reduction in error variance, Snijders and Bosker’s (1994) modeled variance, and a measure of explained variance proposed by Gagné and Furlow (2009).
For each of the explained variance approaches, a cross-validation measurement, shrinkage, was obtained. The results indicate that sample size, predictor-criterion correlations, and centering impact the cross-validation measurement. The degree and direction of the impact differs with the explained variance approach employed. Under some explained variance approaches, shrinkage decreased with larger level-2 sample sizes and increased in others. Likewise, in comparing group- and grand-mean centering, with some approaches grand-mean centering resulted in higher shrinkage estimates but smaller estimates in others. Larger total sample sizes yielded smaller shrinkage estimates, as did the predictor-criterion correlation combination in which the group-level predictor had a stronger correlation. The approaches to explained variance differed substantially in their usability for cross-validation. The Snijders and Bosker approach provided relatively large shrinkage estimates, and, depending on the predictor-criterion correlation, shrinkage under both Raudenbush and Bryk approaches could be sizable to the degree that the estimate begins to lack meaning. Researchers seeking to cross-validate HLM need to be mindful of the interplay between the explained variance approach employed and the impact of sample size, centering, and predictor-criterion correlations on shrinkage estimates when making research design decisions.
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A multilevel analysis of learner and school contextual factors associated with educational qualityWinnaar, Lolita January 2013 (has links)
Magister Philosophiae - MPhil / The South African schools act, (number 5, 1996), asserts that all learners have a
right to access both basic and quality education without discrimination of any sort.
Since the implementation of the Millennium Development Goals there has been a
drive by the Department of Education to ensure that all learners have access to
basic education by 2015. However what remains a challenge after almost 20 years
of democracy is the poor quality of education and this is clear from the results of
international assessment studies. Results from studies like the Trends in
International Mathematics and Science Study and Southern and East Africa
Consortium for Monitoring Educational Quality, show that South African children
perform well below international averages. In this study learner Mathematics
achievement scores taken from the Trends in International Mathematics and
Science Study 2011 cycle will serve as a proxy for educational quality. Using
multilevel analysis the current study aims to use a 2-level Hierarchical Linear
Model to firstly; determine the learner and family background factors associated
with education quality. Secondly; factors at the school level will be identified and
proven to be associated with education quality. Variables selected for the study
was based on Creamer’s theory of school effectiveness which looked at school,
classroom level inputs as well as learner background variables to explain student
level achievement. The results show that at the learner’s level the most significant
factors were the age of the leaner, in the sense that grade age appropriate learners
obtained higher scores than overage learners. Learner’s perception of mathematics
is extremely important and has a positive effect on mathematics performance. In
the current study mathematics perception refers to learners valuing and liking
mathematics as well learner confidence in learning mathematics. Learners who
said they were bullied as school generally scored lower than learners who were
not bullied. At the school level the most significant factors were teacher working
conditions, teachers’ specialisation in mathematics, school socio-economic status,
and general infrastructure. Interesting to note at the school level is when socioeconomic
status was included in the model as a single variable the score difference between low socio-economic status and high socio-economic status schools was almost 46 points. However when the factors mentioned above were added to the model the difference in scores dropped by almost half.
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Reading between the lines : contributing factors that affect Grade 5 learner reading performanceVan Staden, Surette 24 May 2011 (has links)
This study aims to identify and explain relationships between some major factors associated with successful reading at Grade 5 level in South African primary schools. In South Africa, grave concerns with regards to low levels of student achievement pervade research initiatives and educational debates. Despite considerable investments in educational inputs (such as policy and resources) and processes (such as curriculum provision and teacher support), outcomes (such as student achievement) remain disappointingly low. The South African population is characterized by great diversity and variation. With 11 official languages, current educational policy in South Africa advocates an additive bilingualism model and students in Grade 1 to 3 are taught in their mother tongue. Thereafter, when these students progress to Grade 4, the language of learning and teaching changes to a second language, which in most cases is English. At this key developmental stage students are also expected to advance from learning to read to a stage where they can use reading in order to learn. With this complexity of issues in mind, Hierarchical Linear Modeling (HLM) was used to determine the effect of a number of explanatory variables at learner and school level on reading achievement as outcome variable, while controlling for language using the South African Progress in International Reading Literacy Study (PIRLS) 2006 data. As an international comparative evaluation of reading literacy involving more than 40 countries, PIRLS 2006 was the second, after PIRLS 2001, in a series of planned five-year cycles of assessment to measure trends in children’s reading literacy achievement, policy and practices related to literacy. Grade 5 learners in South African primary schools who participated in PIRLS 2006 were not able to achieve satisfactory levels of reading competence. The gravity of this finding is exacerbated by the fact that these learners were tested in the language in which they had been receiving instruction during the Foundation Phase of schooling. This study found most significant factors associated with reading literacy at learner-level, but this does not mean that the existence of teacher- and school-level factors is not of importance. While some explanatory factors at learner-level can more easily become the target of reading interventions, the higher level effect of the classroom and school are not diminished by this study. Creemers’ Comprehensive Model of Educational Effectiveness was utilized as theoretical point of departure. Creemers’ model was adapted for the purposes of this study to reflect a South African model of reading effectiveness in contrast with Creemers’ original use of it as a model of school effectiveness. Evidence was provided that the conceptual framework was inadequate in identifying factors affecting reading achievement for all South African language groupings. More specifically, the adapted South African reading effectiveness model was only appropriate in explaining reading achievement scores for the Afrikaans and English language groupings than for those from African language groupings. / Thesis (PhD)--University of Pretoria, 2010. / Science, Mathematics and Technology Education / unrestricted
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C'est en traduisant qu'on devient traduiseron / You become a translator by translatingVicari, Eliana 19 December 2013 (has links)
Articulée en trois chapitres, cette thèse qui vise à endiguer la toute-puissance de la traductologie porte, d’abord, sur l’analyse d’un extrait de Simenon inséré dans La belle Hortense, puis sur l’examen des erreurs relevées dans 40 versions d’étudiants de l’université de Venise confrontés avec un passage d’Agnès Desarthe et, enfin, sur la traduction du « Maladroit » de Raymond Queneau par Umberto Eco. Comme le titre l’indique, cette thèse revendique l’importance de la pratique. Ce n’est pas à force d’étudier des grammaires qu’un jour on se réveille écrivain, une plume ou un clavier à la main. De même, c’est une évidence, on ne devient pas traducteur sans traduire, bien que l’exercice ne puisse garantir l’excellence du résultat. C’est un truisme, une lapalissade dont il n’est pas inutile de rappeler la vérité, à un moment où la traductologie devient de plus en plus envahissante. Comme toute théorie, elle tend à l’abstraction et à la généralisation, tandis que la pratique, elle, se confronte au hic et nunc. C’est pour cela même qu’elle risque de se révéler non seulement inadéquate, mais aussi dangereuse. Car la littérature, loin d’être l’application de la norme, est le lieu de l’écart. Or, il est difficile de résister à l’autorité d’un dictionnaire, d’un traductologue ou d’un critique, plus difficile encore s’ils sont auréolés de prestige. Toute traduction comporte deux phases. La première est axée sur une analyse stylistique du texte-source et implique une excellente maîtrise de la langue et de la culture de son monde d’origine. C’est le moment de l’esclavage où le traducteur est complètement au service de l’auteur, où il cherche à comprendre sans juger, où – tel un amoureux – il écoute sa voix pour pouvoir l’interpréter. Mais le moment de l’esclavage qui enchaîne au texte originel est aussi le moment de l’apprentissage, le moment où le traducteur peut pénétrer les secrets d’une écriture d’auteur. Sans cette phase préalable, on ne devrait même pas parler de traduction. Si on ne lit pas attentivement – à la loupe – l’œuvre qu’on doit transplanter ou si on ne connaît pas assez la matière dont elle est faite, on finit par se fier aux dictionnaires, par appliquer des recettes toutes faites. C’est une autre voix que celle de l’auteur que l’on entendra, alors, au-delà des frontières. C’est dans cette phase que des préjugés ou des brouillages théoriques assez enracinés ou assez puissants sont intervenus, d’après mon analyse, dans les extraits examinés. Ils ont entraîné la banalisation de Simenon (mais non de Roubaud qui emprunte ses mots) aussi bien que la plupart des incorrections des étudiants (souvent induites paradoxalement par l’usage du dictionnaire). Ils ont poussé également Umberto Eco à remanier radicalement un texte de Raymond Queneau qu’il avait considéré comme l’un des moins réussis, alors qu’il est sans aucun doute l’un des plus importants – et peut-être le plus important - des Exercices de style. Dans la deuxième phase, le traducteur qui accepte d’écrire sous contrainte – sous les contraintes que lui impose le texte-source – connaît aussi la joie de la liberté. Car la contrainte le libérera et le poussera à exploiter toutes les potentialités insoupçonnées, toutes les ressources de la langue et de la culture d’arrivée pour rendre le plus fidèlement la voix de l’auteur, auquel l’analyse et la compréhension l’ont enchaîné. C’est un effort de Sisyphe, mais qui peut rendre heureux. Car c’est aussi en traduisant qu’on devient écriveron. / Set out in three chapters, this thesis which has the aim of investigating the omniscience of translation, starts out by analyzing an extract from Simenon in La Belle Hortense then moves to a study of the mistakes made in 40 translations by students at the University of Venice from a text by Agnès Desarthe and, finally, looks at the translation by Umberto Eco of Raymond Queneau's "Maladroit".As its title suggests, this thesis underlines the importance of practice. One does not suddenly wake up a writer one morning, a pen at the ready simply because one has studied grammar.At the same time one obviously does not become a translator without translating, although practice in itself does not guarantee the excellence of the outcome. This is a truism worth remembering at a moment when translation studies are becoming more and more invasive. Like every theory it tends towards abstraction and generalization while practice concerns itself with the here and now. But it is exactly for this that it risks revealing itself not only as inadequate but also dangerous. For literature, far from being the application of the norm, is where the gap exists. However it is difficult to resist the authority of a dictionary, of a translation expert or of a critic, even more so if they are surrounded by a halo of prestige.Every translation consists of two phases. The first is based on a stylistic analysis of the source text and implies an excellent mastery of the language and of the culture from where it originates. This is the moment of enslavement when the translator is at the complete service of the author, where he tries to understand without judging, like a lover, he listens to his voice so that he can interpret it. But the stage of enslavement which chains one to the original text is also the moment of apprenticeship, the moment when the translator can enter into the secrets of an author's writing. Without this initial phase, one should not even speak of translation. If one does not read carefully, as under a magnifying glass, the work that one must transplant and where one does not know sufficiently what makes it up, one ends up by relying too much on dictionaries, to apply ready-made solutions. There is another voice apart from the author's that one must hear, beyond the normal boundaries.It is in this phase that well-rooted and strong prejudices or theoretical garble, according to my analysis, have intervened in the extracts examined. They have caused a banalisation of Simenon (but not of Roubaud who borrowed his words) as well as most of the errors of the students (and often brought about, paradoxically, the use of dictionaries). In the same way they pushed Umberto Eco to meddle radically with a text of Raymond Queneau that he considered one of the latter's less successful ones, even though it is one of the most important, and perhaps the most important, in Exercices de style.In the second phase, the translator who accepts to write under constraint, under the constraints imposed by the source text, also knows the joy of liberty. Because the constraint will free him and push him to take full advantage of unexpected potentiality, of all the resources of the language and culture and to render the voice of the author in the most faithful way, and to whom the analysis and comprehension chained him. It is the work of Sisyphus but which can create contentment. Because it is also by translating that one becomes a writer.
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La gratuité des soins associée à l’amélioration de la qualité des soins est-elle efficace pour maintenir l’utilisation des services à long terme et améliorer la santé infantile au Burkina Faso ?Zombré, David 02 1900 (has links)
Problématique : L’amélioration de l’accessibilité financière aux soins de santé est essentielle pour réduire la morbidité et de la mortalité infantile dans les pays à ressources limitées. Cependant, les preuves disponibles sur la relation entre un accès accru aux soins et l’amélioration la santé infantile, dans le long terme, demeurent insuffisantes et parfois inconnues. Dans le contexte spécifique de la région du Sahel au Burkina Faso où les niveaux élevés de morbidité et de malnutrition coïncident avec un faible recours aux soins, une intervention de santé publique associant la gratuité des soins à l’amélioration de la qualité des soins et à la prise en charge de la malnutrition dans la communauté a été mise en œuvre en septembre 2008.
Objectifs : En utilisant des approches statistiques et épidémiologiques appliquées aux données transversales et de séries chronologiques, cette thèse vise à apporter une meilleure compréhension de la façon dont la présence de l’intervention dans les communautés peut augmenter et maintenir l’utilisation des services de santé à long terme et améliorer la santé des enfants de moins de cinq ans. Les objectifs spécifiques sont : 1) évaluer le maintien à long terme des effets de l’intervention sur l’utilisation des services de santé chez les enfants de moins de cinq ans, 2) évaluer l’effet contextuel de l’intervention, quatre ans après le début de sa mise en œuvre, sur la probabilité de survenue d’une maladie et sur la probabilité d’utilisation des services de santé chez les enfants de moins de cinq ans, et 3) évaluer l’effet contextuel de l’intervention, quatre ans après le début de sa mise en œuvre, sur le retard de croissance chez les enfants de moins de cinq ans.
Méthodes : Les données proviennent du système national d’information sanitaire, d’une enquête rétrospective sur les services de santé ainsi que d’une enquête de ménages réalisée quatre ans après le début de l’intervention dans 41 villages du district d’intervention et 51 villages du district de comparaison. Nous avons utilisé un plan quasi expérimental à séries temporelles interrompues avec groupe de comparaison pour évaluer les effets immédiats et à long terme de l’intervention sur les taux d’utilisation des services de santé. Ensuite, un plan d’étude transversale post-intervention avec un groupe de comparaison nous a permis d’évaluer l’effet contextuel de l’intervention sur la probabilité de survenue d’une maladie, sur la probabilité d’utilisation des services de santé et sur le retard de croissance chez les enfants de moins de cinq ans. La stratégie analytique a combiné la méthode de pondération par les scores de propension pour équilibrer les covariables entre les deux groupes, la modélisation binomiale négative à effets mixtes, les régressions linéaire et logistique multiniveaux.
Résultats : L’intervention de gratuité des soins associée à l’amélioration de la qualité des soins et à la prise en charge de la malnutrition dans la communauté était associée à l’augmentation et au maintien de l’utilisation des services de santé au-delà de quatre ans (ratio des taux d’incidence = 2,33 ; IC 95 % = 1,98 – 2,67). En outre, comparativement aux enfants vivant dans le district de contrôle, la probabilité d’utiliser les services de santé était de 17,2 % plus élevée chez les enfants vivant dans le district d’intervention (IC 95 % = 15,01–26,6) ; et de 20,7 % plus élevée lorsque l’épisode de maladie était sévère (IC 95 % = 9,9–31,5). Ces associations étaient significatives, quels que soient la distance par rapport aux centres de santé et le statut socio-économique du ménage. Par ailleurs, alors que le contexte de résidence expliquait 9,36 % de la variance du retard de croissance (corrélation intraclasse = 9,36 % ; IC 95 % = 6,45–13,38), la présence de l’intervention dans les villages n’explique que 2 % de la variance du retard de croissance. Cependant, nous n’avons pas pu démontrer que la présence de l’intervention dans les communautés était associée à une réduction de la probabilité de survenue d’un épisode de maladie (Différentiel des probabilités = 4.4 ; IC 95% = -1.0 – 9.8), ni à une amélioration significative de l’état nutritionnel des enfants de moins de cinq ans (RC = 1,13 ; IC 95 % = 0,83–1,54).
Conclusion : Cette thèse souligne que la gratuité des soins associée à l’amélioration de la qualité des soins et à la prise en charge de la malnutrition dans la communauté est efficace pour augmenter et maintenir l’utilisation des services de santé et réduire les inégalités géographiques de recours aux soins. Cependant, cette intervention n’était pas associée à une amélioration des résultats de santé infantile. Bien que des études longitudinales rigoureuses soient nécessaires pour comprendre pleinement l’influence potentielle de cette intervention sur la morbidité, cette thèse plaide pour la nécessité d’agir simultanément sur les autres déterminants sociaux de la santé et d’intégrer, de manière synergique, des interventions spécifiques à la nutrition pour plus d’impact sur la santé infantile. / Introduction: Improving financial access to health care is believed to be essential for reducing the burden of child morbidity and mortality in resource-limited settings, but the available evidence on the relationship between increased access and health remains scarce and the long-term issues are still unknown. In the specific context of the Sahel region in Burkina Faso where high levels of morbidity and malnutrition coincide with low health care use, a pilot intervention for free health care including quality of care improvement and management of malnutrition at the community level was implemented in September 2008.
Objectives:
Using statistical and epidemiological approaches applied to cross-sectional and time series data, this thesis aims to provide a better understanding of how the presence of intervention in communities can increase and maintain long-term use of health services and improve the health of children under five years. The specific objectives are: 1) to evaluate the long-term effects of the intervention on the use of health services in children under the age of five, 2) to estimate the contextual effect of intervention on the probability of occurrence of and the likelihood of health services being used by children under five, four years after the start of its implementation, and 3) to evaluate the contextual effect of the intervention on stunting in children under five, four years after the start of its implementation.
Methods: The data for the analyses were provided from a variety of sources including the national health information system, a retrospective health services survey, and a household survey conducted four years after the intervention onset in 41 villages in the intervention district and 51 villages in the comparison district. We used a quasi-experimental controlled interrupted time-series design group to analyze the immediate and long-term effects of the intervention on the rate of health services utilization in children under five. Then, a quasi-experimental post-test-only design that included a control group allowed us to evaluate the contextual effect of the intervention on the probability of occurrence of a disease, on the probability of use of health services, and stunting in children under five. The analytic strategy combined the propensity score weighting method to balance the covariates between the two groups, two-level mixed-effects negative binomial, and linear and logistic regression models to account for the hierarchical structure of data.
Results: The intervention for free health care including quality of care improvement and management of malnutrition at the community level was associated with an increased and maintained use of health services beyond four years after the onset of intervention (incidence rate ratio = 2.33; 95% CI = 1.98–2.67). In addition, compared to children living in the comparison district, the probability of using health services was 17.2% higher among those living in the intervention district (95% CI = 15.0–26.6); and 20.7% higher when the illness episode was severe (95% CI = 9.9–31.5). These associations were significant regardless of the distance to health centers and the socio-economic status of households. In addition, inequalities in the use of care were less pronounced in the intervention villages compared to those in the control village. Finally, the results also showed that the residence context accounted for 9.36% of the variance in stunting (intra-class correlation = 9.36% ; 95% CI = 6.45–13.38), and only 2% of the variance in stunting was explained by the intervention. However, we could not demonstrate that the intervention in these communities was associated with a reduced probability of an illness occurring (AME=4.4 (95% CI: -1.0 – 9.8), nor with a significant improvement in the nutritional status among children under five (OR = 1.13; 95% CI = 0.83–1.54).
Conclusion: This thesis underlines the importance that affordable health care, including quality of care, as well as improving the management of malnutrition at the community level, are effective in increasing and maintaining the use of health services and reduce geographical inequalities in the use of care. However, this intervention was not associated with improved child health outcomes. Although rigorous longitudinal studies are necessary to fully understand the potential influence of this intervention on morbidity, this thesis highlights the need to simultaneously act on other social determinants of health and to synergistically integrate nutrition-specific interventions for greater impact on child health.
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Hodnocení výkonnosti společnosti metodou benchmarkingu / Corporate Performance Evaluation of CORA MANAGEMENT s. r. o. and Proposals for its ImprovementDusík, Jakub January 2018 (has links)
benchmarking, five-stage model of benchmarking, competition, performance, comparsion
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Zabezpečovací systém pro rodinný dům / Security system for family houseSohr, Martin January 2012 (has links)
Family house, security system, wireless communication, IQRF, RSA, central control unit, SPI, I2C, glass break sensors, motion sensors, magnetic contact sensors, graphic displey, LCD displey, microcontroler, SIM900, 24FJ256GB106, EA DOGM106, eDIPTFT43-A.
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Asynchronní motor s vnějším rotorem / Induction machine with outer rotorChvatík, Štěpán January 2018 (has links)
Induction machine; outer rotor; water pump; thermal network; thermal analysis; optimization; electromagnetic model; finite element method; thermal insulation class
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