This study deals with the relationship between culture and national development in Angola. It is self-evident that folktales are integral to the cultural heritage of any people, and the Lunda-Cokwe of Angola are no exception. Folktales pass on their knowledge and general cultural heritage to new generation. However, they are rarely regarded as a useful component on development process of a country. In general the development is largely measured in statistics reflecting material wealth. It maintains that, in order to bring about sustainable development and national unity, a holistic approach to personality building as well as nation building is required. The argumentation will not only take into account economic capital generated through national resources, such as diamonds from the Lunda provinces, but also requires other forms of capital, including social and cultural capital as articulated in Bourdieu’s theory of capital. / African languages / M.A. (African languages)

Os mapas conceituais são ferramentas gráficas que possibilitam a representação dos modelos mentais do aluno. Devido a essa capacidade, o mapa conceitual pode ser utilizado como ferramenta avaliativa de conhecimento. O uso dessa ferramenta em sala de aula gera cargas na memória de trabalho que podem ser referentes ao conteúdo (carga intrínseca) ou à forma como esse recurso está sendo trabalhado na sala de aula (carga extrínseca). Este trabalho tem por objetivo investigar como os mapas conceituais auxiliam na avaliação da aprendizagem da disciplina Ciências da Natureza: Ciência, Cultura e Sociedade ofertada na Universidade de São Paulo para alunos ingressantes de diversos cursos de graduação (n = 64) durante o período de 2013.1 sobre o conteúdo de Mudanças Climáticas. Nas turmas avaliadas o mapa conceitual poderia ser utilizado como ferramenta de preparação para prova (MCPREP) como também era utilizado como parte da avaliação formal da disciplina (MC-AVAL). Essa pesquisa se constitui de três Estudos que investigam: 1. As diferenças de perfis de mapas conceituais obtidos na condição de MC-PREP x MCAVAL; 2. Se o grupo de alunos que fizeram MC-PREP tiveram MC-AVAL com perfil diferente daqueles que não fizeram; 3. A existência de uma correlação entre as características do MC-AVAL com o conhecimento declarativo dos estudantes. Os mapas conceituais foram avaliados considerando aspectos estruturais e semânticos. As metodologias das análises realizadas foram retiradas de trabalhos presente na literatura. Entre os aspectos semânticos estavam o uso de materiais instrucionais, a natureza das proposições, a presença de erros e a aderência a pergunta focal. Além dessas análises, foi verificada a presença de agrupamentos naturais que pudessem ser explicados com uso das categorias teóricas. A análise dos resultados indica que os mapas conceituais das condições MC-PREP e MC-AVAL são bastante distintas entre si, pois atendiam a objetivos educacionais diferentes. No Estudo 2 verificou-se que o MC-PREP não influenciou fortemente a elaboração do MC-AVAL, pois a diminuição da carga extrínseca provocada pela elaboração de MC-PREP não foi suficiente para mostrar diferenças entre os grupos, já que ambos estavam altamente treinados na técnica de mapeamento conceitual. Por fim, no Estudo 3, o principal fator correlacionando o conhecimento declarativo com a complexidade dos mapas conceituais foi o percentual de proposições apropriadas. As conclusões do trabalho são que a demanda de elaboração do mapa conceitual é realmente orientadora de produto, a elaboração de um mapa conceitual a mais em um grupo bem treinado na técnica não altera seu desempenho e o principal meio de avaliar os mapas conceituais deve ser a leitura de suas proposições constituintes. / Concept maps are graphical tools that allows the representation of the student\'s mental models. Due to this capacity, the concept map can be used as an assessement tool of knowledge. The use of this tool in the classroom generates loads in working memory which can be related to the content (intrinsic load) or how this feature is being used in the classroom (extrinsic load). This study aims to investigate how the concept maps help to assess learning in the Natural Science: Science, Culture and Society course offered at the University of São Paulo for students of various undergraduate courses (n = 64) during the 2013.1 on the content of climate change. In the course, conceptual map could be used as a preparation tool for test (CM-PREP) and was also used as part of the formal evaluation of the course (CM-EVAL). This research is composed of three studies that investigate: 1. Differences in conceptual maps profiles obtained on condition of CM-PREP x CMEVAL; 2. If the group of students who took CM-PREP had a different profile in CMAVAL of those who did not; 3. The existence of a correlation between CM-EVAL features with the declarative knowledge of students. Concept maps were evaluated considering structural and semantic aspects. The methodologies of analyzes are taken from other papers. Among the semantic aspects were the use of instructional materials, the nature of the propositions, the presence of errors and adhesion to focus question. In addition to these analyzes, it was verified the presence of natural groups that could be explained with the use of theoretical categories. Analysis of the results indicates that the conceptual maps of the CM-PREP and CM-EVAL conditions are quite distinct from each other as it catered to different educational goals. At the Study 2, it was found that the CM-PREP not strongly influenced the development of CM-EVAL, as the reduction of extrinsic charge caused by CM-PREP elaboration was not enough to show differences between the groups, since both were highly trained in conceptual mapping technique. Finally, in Study 3, the main factor correlating the declarative knowledge to the complexity of the conceptual maps was the percentage of appropriate propositions. We concluded that the demand of elaboration of the conceptual map is actually the guide to the type of conceptual map obtained, the elaboration of CM-PREP does not change in a well-trained group in the technique and the main method of assessing concept maps should be reading its propositions.

O objetivo desta pesquisa foi o de analisar o processo de mudanças e integração vivenciados por alunos ingressantes no Ensino Superior, que cursaram a disciplina on-line Metodologia do Estudo no primeiro semestre de 2016. Os sujeitos da pesquisa foram calouros do curso Ciência da Computação (CCO) de uma instituição particular do Estado de São Paulo. O estudo buscou refletir sobre alguns aspectos de como os ingressantes lidam com as exigências do ensino superior, que são diferentes das da educação básica, bem como conhecer suas opiniões sobre este novo momento de suas vidas acadêmica e de formação. A pesquisa orientou-se pelos princípios da abordagem qualitativa, com métodos múltiplos de coleta de dados, que envolveram: análise das atividades propostas e das ações dos alunos na disciplina no ambiente virtual; análise das respostas aos questionários on-line propostos nas duas primeiras semanas (Ambientação on-line) da disciplina; realização de entrevistas com alguns alunos da turma e com a coordenadora do curso, bem como a seleção e análise de relatórios gerados pelo ambiente virtual e de documentos institucionais. A estratégia metodológica utilizada na investigação foi o Estudo de Caso. A importância dessa investigação é ressaltada pelos posicionamentos de teóricos que consideram o momento de transição do ensino médio para o ensino superior pleno de mudanças e situações novas que o jovem precisa superar. Além disso, considerou-se o desafio de aprender no contexto digital. Ao final, foi ressaltada a importância de oferecimento de disciplinas on-line que se preocupem com a integração dos alunos na cultura universitária e que os auxiliem na aquisição de hábitos de autodisciplina para estudar e se organizar. Verificou-se também a relevância do uso de estratégias didáticas on-line interativas que viabilizem as trocas comunicativas entre os estudantes e as descobertas de seus estilos e desejos de aprendizagem que orientem os seus caminhos de formação. / The objective of this research was to analyze the process of changes and integration experienced by students who started College and attended the online course called Study Methodology in the first semester of 2016. The subjects of the research were freshmen of the course Computer Science of a private institution located in the State of São Paulo. The study sought to reflect about some aspects such as how freshmen deal with the demands of College, which are different from those of High School, as well as to learn their opinions about this new moment of their academic lives and formation. The research was guided by the principles of the qualitative approach, with multiple methods of data collection, which involved: analysis of the proposed activities and the actions of the students in the virtual environment; analysis of the answers to the on-line questionnaires proposed in the first two weeks of the course (online setting); conducting interviews with some students of the class and with the coordinator of the course and the selection and analysis of reports generated by the virtual environment and of institutional documents. The methodological strategy used in the research was the Case Study. The importance of this research is highlighted by the positions of theorists who consider that the moment of transition from high school to college is full of changes and new challenges that young people need to overcome. In addition, the challenge of learning in the digital context was considered. At the end, the work highlighted the importance of offering online courses that are focused on the integration of students in the university culture and that help them to acquire habits of self-discipline to study and organize themselves. The work was also verified the importance of the use of interactive online didactic strategies that enable the communicative exchanges between the students and the discoveries of their styles and learning desires which will guide their formation paths.

O objetivo desta pesquisa foi o de analisar o processo de mudanças e integração vivenciados por alunos ingressantes no Ensino Superior, que cursaram a disciplina on-line Metodologia do Estudo no primeiro semestre de 2016. Os sujeitos da pesquisa foram calouros do curso Ciência da Computação (CCO) de uma instituição particular do Estado de São Paulo. O estudo buscou refletir sobre alguns aspectos de como os ingressantes lidam com as exigências do ensino superior, que são diferentes das da educação básica, bem como conhecer suas opiniões sobre este novo momento de suas vidas acadêmica e de formação. A pesquisa orientou-se pelos princípios da abordagem qualitativa, com métodos múltiplos de coleta de dados, que envolveram: análise das atividades propostas e das ações dos alunos na disciplina no ambiente virtual; análise das respostas aos questionários on-line propostos nas duas primeiras semanas (Ambientação on-line) da disciplina; realização de entrevistas com alguns alunos da turma e com a coordenadora do curso, bem como a seleção e análise de relatórios gerados pelo ambiente virtual e de documentos institucionais. A estratégia metodológica utilizada na investigação foi o Estudo de Caso. A importância dessa investigação é ressaltada pelos posicionamentos de teóricos que consideram o momento de transição do ensino médio para o ensino superior pleno de mudanças e situações novas que o jovem precisa superar. Além disso, considerou-se o desafio de aprender no contexto digital. Ao final, foi ressaltada a importância de oferecimento de disciplinas on-line que se preocupem com a integração dos alunos na cultura universitária e que os auxiliem na aquisição de hábitos de autodisciplina para estudar e se organizar. Verificou-se também a relevância do uso de estratégias didáticas on-line interativas que viabilizem as trocas comunicativas entre os estudantes e as descobertas de seus estilos e desejos de aprendizagem que orientem os seus caminhos de formação. / The objective of this research was to analyze the process of changes and integration experienced by students who started College and attended the online course called Study Methodology in the first semester of 2016. The subjects of the research were freshmen of the course Computer Science of a private institution located in the State of São Paulo. The study sought to reflect about some aspects such as how freshmen deal with the demands of College, which are different from those of High School, as well as to learn their opinions about this new moment of their academic lives and formation. The research was guided by the principles of the qualitative approach, with multiple methods of data collection, which involved: analysis of the proposed activities and the actions of the students in the virtual environment; analysis of the answers to the on-line questionnaires proposed in the first two weeks of the course (online setting); conducting interviews with some students of the class and with the coordinator of the course and the selection and analysis of reports generated by the virtual environment and of institutional documents. The methodological strategy used in the research was the Case Study. The importance of this research is highlighted by the positions of theorists who consider that the moment of transition from high school to college is full of changes and new challenges that young people need to overcome. In addition, the challenge of learning in the digital context was considered. At the end, the work highlighted the importance of offering online courses that are focused on the integration of students in the university culture and that help them to acquire habits of self-discipline to study and organize themselves. The work was also verified the importance of the use of interactive online didactic strategies that enable the communicative exchanges between the students and the discoveries of their styles and learning desires which will guide their formation paths.

Os mapas conceituais são ferramentas gráficas que possibilitam a representação dos modelos mentais do aluno. Devido a essa capacidade, o mapa conceitual pode ser utilizado como ferramenta avaliativa de conhecimento. O uso dessa ferramenta em sala de aula gera cargas na memória de trabalho que podem ser referentes ao conteúdo (carga intrínseca) ou à forma como esse recurso está sendo trabalhado na sala de aula (carga extrínseca). Este trabalho tem por objetivo investigar como os mapas conceituais auxiliam na avaliação da aprendizagem da disciplina Ciências da Natureza: Ciência, Cultura e Sociedade ofertada na Universidade de São Paulo para alunos ingressantes de diversos cursos de graduação (n = 64) durante o período de 2013.1 sobre o conteúdo de Mudanças Climáticas. Nas turmas avaliadas o mapa conceitual poderia ser utilizado como ferramenta de preparação para prova (MCPREP) como também era utilizado como parte da avaliação formal da disciplina (MC-AVAL). Essa pesquisa se constitui de três Estudos que investigam: 1. As diferenças de perfis de mapas conceituais obtidos na condição de MC-PREP x MCAVAL; 2. Se o grupo de alunos que fizeram MC-PREP tiveram MC-AVAL com perfil diferente daqueles que não fizeram; 3. A existência de uma correlação entre as características do MC-AVAL com o conhecimento declarativo dos estudantes. Os mapas conceituais foram avaliados considerando aspectos estruturais e semânticos. As metodologias das análises realizadas foram retiradas de trabalhos presente na literatura. Entre os aspectos semânticos estavam o uso de materiais instrucionais, a natureza das proposições, a presença de erros e a aderência a pergunta focal. Além dessas análises, foi verificada a presença de agrupamentos naturais que pudessem ser explicados com uso das categorias teóricas. A análise dos resultados indica que os mapas conceituais das condições MC-PREP e MC-AVAL são bastante distintas entre si, pois atendiam a objetivos educacionais diferentes. No Estudo 2 verificou-se que o MC-PREP não influenciou fortemente a elaboração do MC-AVAL, pois a diminuição da carga extrínseca provocada pela elaboração de MC-PREP não foi suficiente para mostrar diferenças entre os grupos, já que ambos estavam altamente treinados na técnica de mapeamento conceitual. Por fim, no Estudo 3, o principal fator correlacionando o conhecimento declarativo com a complexidade dos mapas conceituais foi o percentual de proposições apropriadas. As conclusões do trabalho são que a demanda de elaboração do mapa conceitual é realmente orientadora de produto, a elaboração de um mapa conceitual a mais em um grupo bem treinado na técnica não altera seu desempenho e o principal meio de avaliar os mapas conceituais deve ser a leitura de suas proposições constituintes. / Concept maps are graphical tools that allows the representation of the student\'s mental models. Due to this capacity, the concept map can be used as an assessement tool of knowledge. The use of this tool in the classroom generates loads in working memory which can be related to the content (intrinsic load) or how this feature is being used in the classroom (extrinsic load). This study aims to investigate how the concept maps help to assess learning in the Natural Science: Science, Culture and Society course offered at the University of São Paulo for students of various undergraduate courses (n = 64) during the 2013.1 on the content of climate change. In the course, conceptual map could be used as a preparation tool for test (CM-PREP) and was also used as part of the formal evaluation of the course (CM-EVAL). This research is composed of three studies that investigate: 1. Differences in conceptual maps profiles obtained on condition of CM-PREP x CMEVAL; 2. If the group of students who took CM-PREP had a different profile in CMAVAL of those who did not; 3. The existence of a correlation between CM-EVAL features with the declarative knowledge of students. Concept maps were evaluated considering structural and semantic aspects. The methodologies of analyzes are taken from other papers. Among the semantic aspects were the use of instructional materials, the nature of the propositions, the presence of errors and adhesion to focus question. In addition to these analyzes, it was verified the presence of natural groups that could be explained with the use of theoretical categories. Analysis of the results indicates that the conceptual maps of the CM-PREP and CM-EVAL conditions are quite distinct from each other as it catered to different educational goals. At the Study 2, it was found that the CM-PREP not strongly influenced the development of CM-EVAL, as the reduction of extrinsic charge caused by CM-PREP elaboration was not enough to show differences between the groups, since both were highly trained in conceptual mapping technique. Finally, in Study 3, the main factor correlating the declarative knowledge to the complexity of the conceptual maps was the percentage of appropriate propositions. We concluded that the demand of elaboration of the conceptual map is actually the guide to the type of conceptual map obtained, the elaboration of CM-PREP does not change in a well-trained group in the technique and the main method of assessing concept maps should be reading its propositions.

This research report is a narrative on my encounter with sport psychology. I used the metaphors of “touring” and “journal” to guide the construction of this narrative. Before embarking on my tour with sport psychology, I introduced myself as researcher (chapter 2, journal entry I) and stated the research problem, question and goal(s)(chapter 3, journal entry II). I then went on a tour with sport psychology. I visited a sport psychology museum to learn more about the history of sport psychology (chapter 4, journal entry III) and a sport psychology library to learn more about the field of sport psychology (chapter 5, journal entry IV). I also attended a sport psychology conference to become better acquainted with postgraduate sport psychology training in Psychology Departments (chapter 6, journal entry V). I also visited a sport psychology department at a university in Australia, to witness the delivery of a postgraduate training programme in sport psychology (chapter 7, journal entry VI), as well as a sport centre in South Africa and a sport institute in Australia, to see how and the extent to which sport psychology was practised (chapter 8, journal entry VII). After my tour with sport psychology I took what I had learnt and adapted the MA (Counselling Psychology) programme at the University of Pretoria, South Africa. This led to the programme having three core modules and two elective modules. The core modules are fundamental psychology, counselling psychology and career psychology. The elective modules are: community psychology and sport psychology. The sport psychology module consists of the following courses: sport psychology, sport management, sport sociology and exercise psychology. The Professional Board of Psychology at the Health Professions Council of South Africa approved this module at the end of 2003 (chapter 9, journal entry VIII). Finally, I also looked at the influence of my experience with sport psychology on my identity as a psychologist (chapter 10, journal entry IX). / Thesis (PhD (Psychology))--University of Pretoria, 2006. / Psychology / unrestricted

This study investigated the relationships between diverse variables and secondary school pupils' Mathematics achievement. It also dealt with the relative contribution of each variable to Mathematics achievement and the significance of differences in Mathematics achievements when pupils' gender and home background as well as teachers' experience, gender, education, in-service education, homework assignment and testing frequency are taken into account. A questionnaire was administered on 163 standard 8 pupils. I The most important findings of this study were: {1) There was a significant relationship between pupil variables and Mathematics achievement. (2) Pupil variables, particularly self-concept, contributed significantly towards the variance in Mathematics achievement. (3) Pupils who wrote tests often (more than once per term) achieved significantly less than students who wrote tests less often / Psychology of Education / M. Ed. (Psychology of Education)

為了針對實證股價與交易量的資訊，能否作為預測未來政治事件結果提供依據，此篇論文探究四個政治事件，分別是2014年台北市長選舉國民黨黨內初選、2014年台北市長選舉、2016年總統選舉國民黨更換候選人以及2016年總統選舉。作者使用異常交易量作為判斷投資人是否將政治事件視為投資機會，並觀察個股與投資組合之累積異常報酬率是否能作為預測依據，最後以事件後五日內的異常累積報酬判斷投資人是否在事前過度反應或是反應不足。 　　本研究發現，在政治事件發生前六十日內，大部分政治相關的個股交易量皆顯著異於前一年之交易量。與勝選相關的股票在事件前60日至31日有顯著的正累積異常報酬。相較之下，與敗選相關的股票中，僅有和候選人有緊密政治連結的股票有顯著負累積異常報酬，政策相關的股票並無顯著負累計異常報酬。最後，在現行交易制度下，正異常報酬伴隨著正異常交易量，而負異常報酬卻因放空限制等因素，無顯著正異常交易量。 / This paper analyzes the last four political events, which includes KMT's Taipei Mayoral Primary, Taipei Mayor Election, KMT Presidential Candidate Replacement and Taiwan Presidential Election. We use trading volume to detect whether investors join the market due to potential political investment opportunity. Then we examine the CAR tendency with the political event results to identify its forecast ability. Last, we detect CAR within 5 days later to find if investor overreact or underreact before the event day. We find that the CAR meets voters’ political anticipation before the event window. Investors believe they can time the market through these events and gain profit. Furthermore, stocks relevant to those elects experience positive CAR. In contrast, stocks relevant to those also-rans do not experience significant returns. The only fortuneteller is the company, which has close relationship to the defeated candidate, telling with negative CAR. Because of short-sale constrains, the trading volume are not larger than before even it is a good chance to gain profit in the political events.

This study investigated the relationships between diverse variables and secondary school pupils' Mathematics achievement. It also dealt with the relative contribution of each variable to Mathematics achievement and the significance of differences in Mathematics achievements when pupils' gender and home background as well as teachers' experience, gender, education, in-service education, homework assignment and testing frequency are taken into account. A questionnaire was administered on 163 standard 8 pupils. I The most important findings of this study were: {1) There was a significant relationship between pupil variables and Mathematics achievement. (2) Pupil variables, particularly self-concept, contributed significantly towards the variance in Mathematics achievement. (3) Pupils who wrote tests often (more than once per term) achieved significantly less than students who wrote tests less often / Psychology of Education / M. Ed. (Psychology of Education)

La fibrillation auriculaire (FA), l’arythmie cardiaque la plus courante est un facteur de risque majeur pour le développement de l’accident vasculaire cérébral ischémique (AVC). Les anticoagulants oraux directs (AOD) ont largement remplacé la warfarine en usage clinique pour la prévention des AVC dans la FA. Cette recherche a examiné deux défis méthodologiques importants qui peuvent survenir dans les études observationnelles sur l’efficacité et l’innocuité comparatives des AOD et de la warfarine. Premièrement : un biais d’information résultant d’une classification erronée de l’exposition au traitement à la warfarine suite aux ajustements de doses fréquentes qui ne sont pas adéquatement consignés dans les données de dispensations pharmacologiques. Deuxièmement : un biais de sélection, en raison de la censure informative, généré par des mécanismes de censure différentiels, chez les patients exposés aux AOD, ou à la warfarine. À l’aide des données administratives du Québec, j’ai mené trois études de cohortes rétrospectives qui ont portées sur toutes les personnes ayant initié un anticoagulant oral de 2010 à 2016. Ces études étaient restreintes aux résidents du Québec couverts par le régime public d'assurance médicaments (environ 40% de la population au Québec), c’est-à-dire : des personnes âgées de 65 ans et plus; des bénéficiaires de l’aide sociale; des personnes qui n’ont pas accès à une assurance-maladie privée; et les personnes à leur charge. Dans la première étude, nous avons émis l'hypothèse que les données sur les réclamations en pharmacie ne reflètent pas correctement la durée de la dispensation de la warfarine. Les écarts entre les renouvellements consécutifs étaient plus grands pour la warfarine que les AOD. Dans cette étude, on a trouvé que l'écart moyen pour les usagers de la warfarine était de 9.3 jours (avec un intervalle de confiance de 95% [IC]: 8.97-9.59), l'apixaban de 3.08 jours (IC de 95%: 2.96--3.20), et de 3.15 jours pour le rivaroxaban (IC de 95%: 3.03-3.27). Les écarts entre les renouvellements consécutifs présentaient une plus grande variabilité chez les personnes qui prenaient de la warfarine comparativement à celles qui prenaient des AOD. Cette variation peut refléter les changements de posologie de la warfarine lorsque la dose quotidienne est ajustée par le professionnel de la santé en fonction des résultats du rapport normalisé international (INR). L’ajustement de la dose peut prolonger (ou raccourcir) la période couverte par le nombre de comprimés délivrés. Dans la deuxième étude, nous avons émis l'hypothèse que la définition de la durée d'exposition basée sur la variable des « jours fournis », disponible dans la base de données, et le délai de grâce fixe, entraîneront une erreur de classification différentielle de l’exposition à la warfarine par rapport aux AOD. Dans cette étude, on a utilisé deux approches pour définir la durée des dispensations : la variable des « jours fournis » disponible dans la base de données ainsi qu’une approche axée sur les données pour la définition de la durée de dispensation qui tient compte des antécédents de distribution précédents. La deuxième étude a révélé qu'en utilisant la variable des « jours fournis », la durée moyenne (et l'écart type) des durées des dispensations pour le dabigatran, le rivaroxaban, et la warfarine étaient de 19 (15), 19 (14), et de 13 (12) jours, respectivement. En utilisant l’approche fondée sur des données, les durées étaient de 20 (16), 19 (15), et de 15 (16) jours, respectivement. Ainsi, l'approche fondée sur les données s’est rapprochée de la variable des « jours fournis » pour les thérapies à dose standard telles que le dabigatran et le rivaroxaban. Une approche axée sur les données pour la définition de la durée de dispensation, qui tient compte des antécédents de distribution précédents, permet de mieux saisir la variabilité de la durée de dispensation de la warfarine par rapport à la méthode basée sur la variable des « jours fournis ». Toutefois, cela n’a pas eu d’impact sur les estimations du rapport de risque sur la sécurité comparative des AOD par rapport à la warfarine. Dans la troisième étude, nous avons émis l'hypothèse que lors de l'évaluation de l’effet d’un traitement continu avec des anticoagulants oraux (l'analyse per-protocole), la censure élimine les patients les plus malades du groupe des AOD et des patients en meilleure santé du groupe de warfarine. Cela peut baisser l'estimation de l'efficacité et de l'innocuité comparative en faveur des AOD. L’étude a démontré que les mécanismes de censure chez les initiateurs d’AOD et de warfarine étaient différents. Ainsi, certaines covariables pronostiquement significatives, telles que l’insuffisance rénale chronique et l’insuffisance cardiaque congestive, étaient associées avec une augmentation de la probabilité de censure chez les initiateurs d’AOD, et une diminution de la probabilité de censure chez les initiateurs de warfarine. Pour corriger le biais de sélection introduit par la censure, nous avons appliqué la méthode de pondération par la probabilité inverse de censure. Deux stratégies de spécification du modèle pour l’estimation des poids de censure ont été explorées : le modèle non stratifié, et le modèle stratifié en fonction de l’exposition. L’étude a démontré que lorsque les poids de censure sont générés sans tenir compte des dynamiques de censure spécifiques, les estimés ponctuels sont biaisés de 15% en faveur des AOD par rapport à l'ajustement des estimés ponctuels avec des poids de censure stratifiée selon l’exposition (rapport de risque: 1.41; IC de 95%: 1.34, 1.48 et rapport de risque: 1.26; IC de 95%: 1.20, 1.33, respectivement). Dans l’ensemble, les résultats de cette thèse ont d’importantes implications méthodologiques pour les futures études pharmacoépidémiologiques. À la lumière de ceux-ci, les résultats des études observationnelles précédentes peuvent être revus et une certaine hétérogénéité peut être expliquée. Les résultats pourraient également être extrapolés à d’autres questions cliniques. / Atrial fibrillation (AF), the most common cardiac arrhythmia is a major risk factor for the development of ischemic stroke. Direct oral anticoagulants (DOACs) replaced warfarin in clinical use for stroke prevention in AF. This research investigated two important methodological challenges that may arise in observational studies on the comparative effectiveness and safety of DOACs and warfarin. First, an information bias resulting from misclassification of exposure to dose-varying warfarin therapy when using days supplied value recorded in pharmacy claims data. Second, a selection bias due to informative censoring with differential censoring mechanisms in the DOACs- and the warfarin exposure groups. Using the Québec administrative databases, I conducted three retrospective cohort studies that included patients initiating an oral anticoagulant between 2010 and 2016. The studies were restricted to Québec residents covered by the public drug insurance plan (about 40% of Québec’s population), including those aged 65 years and older, welfare recipients, those not covered by private medical insurance, and their dependents. In the first study, we hypothesized that pharmacy claims data inadequately captured the duration of the dispensation of warfarin. Gaps between subsequent dispensations (refill gaps) and their variation are larger for warfarin than for DOACs. In this study, we found that the average refill gap for the users of warfarin was 9.3 days (95% confidence interval [CI]:8.97-9.59), apixaban 3.08 days (95%CI: 2.96--3.20), dabigatran 3.70 days (95%CI: 3.56-3.84) and rivaroxaban 3.15 days (95%CI: 3.03-3.27). The variance of refill gaps was greater among warfarin users than among DOAC users. This variation may reflect the changes in warfarin posology when the daily dose is adjusted by a physician or a pharmacist based on previously observed international normalized ratio (INR) results. The dose adjustment may lead to a prolongation of the period covered by the number of dispensed pills. In the second study, we hypothesized that the definition of duration of dispensation based on the days supplied value and a fixed grace period will lead to differential misclassification of exposure to warfarin and DOACs. This may bias the estimate of comparative safety in favor of DOACs. In this study, we used two approaches to define the duration of dispensations: the recorded days supplied value, and the longitudinal coverage approximation (data-driven) that may account for individual variation in drug usage patterns. The second study found that using the days supplied, the mean (and standard deviation) dispensation durations for dabigatran, rivaroxaban, and warfarin were 19 (15), 19 (14), and 13 (12) days, respectively. Using the data-driven approach, the durations were 20 (16), 19 (15), and 15 (16) days, respectively. Thus, the data-driven approach closely approximated the recorded days supplied value for the standard dose therapies such as dabigatran and rivaroxaban. For warfarin, the data-driven approach captured more variability in the duration of dispensations compared to the days supplied value, which may better reflect the true drug-taking behavior of warfarin. However, this did not impact the hazard ratio estimates on the comparative safety of DOACs vs. warfarin. In the third study, we hypothesized that when assessing the effect of continuous treatment with oral anticoagulants (per-protocol effect), censoring removes sicker patients from the DOACs group and healthier patients from the warfarin group. This may bias the estimate of comparative effectiveness and safety in favor of DOACs. The study showed that the mechanisms of censoring in the DOAC and the warfarin exposure groups were different. Thus, prognostically meaningful covariates, such as chronic renal failure and congestive heart failure, had an opposite direction of association with the probability of censoring in the DOACs and warfarin groups. To correct the selection bias introduced by censoring, we applied the inverse probability of censoring weights. Two strategies for the specification of the model for the estimation of censoring weights were explored: exposure-unstratified and exposure-stratified. The study found that exposure-unstratified censoring weights did not account for the differential mechanism of censoring across the treatment group and failed to eliminate the selection bias. The hazard ratio associated with continuous treatment with warfarin versus DOACs adjusted with exposure unstratified censoring weights was 15% biased in favor of DOACs compared to the hazard ratio adjusted with exposure-stratified censoring weights (hazard ratio: 1.41; 95% CI: 1.34, 1.48 and hazard ratio: 1.26; 95%CI: 1.20, 1.33, respectively). Overall, the findings of this thesis have important methodological implications for future pharmacoepidemiologic studies. Moreover, the results of the previous observational studies can be reappraised, and some heterogeneity can be explained. The findings can be extrapolated to other clinical questions.