Analysis of variance (ANOVA) is a robust test against the normality assumption, but it may be inappropriate when the assumption of homogeneity of variance has been violated. Welch ANOVA and the Kruskal-Wallis test (a non-parametric method) can be applicable for this case. In this study we compare the three methods in empirical type I error rate and power, when heterogeneity of variance occurs and find out which method is the most suitable with which cases including balanced/unbalanced, small/large sample size, and/or with normal/non-normal distributions.

Previous scholarship has highlighted the validity and reliability of a bidimensional acculturation model for migrants, allowing for simultaneous endorsement of one’s heritage and national culture. So far, however, no empirical research has explored whether the bidimensional acculturation model can be extended from migrants to members of the mainstream society (i.e., locals). Thus, the broad aims of this dissertation were threefold: (a) to validate a new framework, termed the Extended Acculturation Model for Locals (EAML), which consists of two dimensions (i.e., national culture maintenance and multicultural adaptation), and (b) to examine the outcomes as well as (c) antecedents of these dimensions. In this dissertation, the General Introduction outlines the growth of multiculturalism across societies, followed by a review of existing acculturation research on migrants and the analogous work on locals. It is noted that migrants’ acculturation process implies individual-level changes, whilst locals’ acculturation process implies attitudes and behaviours which hinder or foster migrants’ individual-level changes. The Study Overview outlines the dimensionality of locals’ acculturation process, their adjustment outcomes and antecedents. Using a modified Vancouver Index of Acculturation (Multi-VIA), Study 1 found support for a bidimensional acculturation model for locals consisting of two reliable and valid subscales indicating national culture maintenance and multicultural adaptation. Study 2 buttresses the validity and reliability of the Multi-VIA across cultures as well as demonstrates the ability of national culture maintenance and multicultural adaptation to predict locals’ sociocultural and psychological adjustment outcomes. Study 3 explains why the correlation between locals’ national culture maintenance and multicultural adaptation is either orthogonal or positive oblique; more specifically, the correlation is moderated by locals’ degree of multicultural exposure, their likeliness to compartmentalize or blend their multicultural identity as well as through high or low self-construal endorsement. Study 4 demonstrates that national culture maintenance and multicultural adaptation predict local employees’ organizational behaviour in multinational corporations. Study 5 revealed that cultural values endorsed at the individual-level predicted locals’ national culture maintenance and multicultural adaptation. Moreover, these individual-level value-outcome associations were moderated by compatible societal-level pro-diversity messages. The General Discussion reviews all of the study findings as well as discusses their implications. The General Limitations and Future Directions describes the theoretical and methodological shortcomings of the Extended Acculturation Model for Locals whilst setting future directions for research. Last, the Final Remarks stresses the overall strengths of the present dissertation – that is, it fills the present research gap on locals’ acculturation towards multiculturalism, and in turn, provides a new route towards harmonious intergroup relations and social cohesion in mixing societies.

Eye tracking is commonly used in many scientific fields (experimental psychology, neuroscience, behavioral economics, etc.) and can provide us with rigorous data about current allocation of attention. Due to the complexity of data processing and missing methodology, experimental designs are often limited to static stimuli; eye tracking data is analyzed only with respect to basic types of eye movements - fixation and saccades. In dynamic tasks (e.g. with dynamic stimuli, such as showing movies or Multiple Object Tracking task), another type of eye movement is commonly present: smooth pursuit. Importantly, eye tracking data from dynamic tasks is often represented as raw data samples. It requires a different approach to analyze the data, and there are a lot of methodological gaps in analytical tools. This thesis is divided into three parts. In the first part, we gave an overview of current methods for analyzing scan patterns, followed by four simulations, in which we systematically distort scan patterns and measure the similarity using several commonly used metrics. In the second part, we presented the current approaches to statistical testing of differences between groups of scan patterns. We present two novel strategies for analyzing statistically significant differences between groups of scan patterns and...

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A Internet vem transformando a maneira como as pessoas compram e buscam por informações sobre produtos. Para locais onde as ofertas físicas apresentam algum tipo de restrição, os canais online podem trazer mudanças ainda mais significativas, já que oferecem aos consumidores um sortimento virtualmente ilimitado. O objetivo deste trabalho foi o de analisar a influência do número de habitantes de uma cidade em relação à predisposição à seleção e compra de produtos de uma empresa que administra campanhas de divulgação pela Internet para venda por atacado. As cidades foram divididas em três grupos conforme o número de habitantes e as principais métricas de performance das campanhas online foram comparadas entre os grupos através de análises de estatísticas descritivas, ANOVA e testes post hoc. Os grupos apresentaram diferenças estatisticamente significativas entre si em todas as etapas do processo de busca e compra. A principal diferença encontrada foi no momento em que os usuários preencheram cadastros no site, demonstrando interesse nos produtos. Nesta etapa, os consumidores de municípios de menor porte se cadastraram proporcionalmente mais do que o dobro dos de cidades de porte intermediário e mais de três vezes em relação ao grupo das maiores, o que impactou diretamente no custo por venda realizada e nas taxas absolutas de vendas. / The Internet has been changing the way people buy and search for new products. In places where the assortment in brick-and-mortar stores is restricted, online channels may represent a significant change in the landscape, due to the fact that they carry virtually unlimited offers. The aim of this study is to analyze the influence of the number of inhabitants of a city on their likelihood of selecting and purchasing products from a company which runs online marketing campaigns for resellers. The cities were divided in three groups according to the population size. In addition, the main metrics for online campaigns were compared among groups through descriptive statistics, ANOVAs and pot hoc tests. There was a statistically significant difference among the groups in all steps of the search and purchase process. The main difference was found when the users fill in the forms in the website, demonstrating interest in the product. In this stage, customers from smaller cities showed a registering rate which was more than twice as much higher than the medium-sized cities group and more than three times the amount of the larger cities group, which led to a direct impact on the cost-per-sale and absolute sales rates.

A Internet vem transformando a maneira como as pessoas compram e buscam por informações sobre produtos. Para locais onde as ofertas físicas apresentam algum tipo de restrição, os canais online podem trazer mudanças ainda mais significativas, já que oferecem aos consumidores um sortimento virtualmente ilimitado. O objetivo deste trabalho foi o de analisar a influência do número de habitantes de uma cidade em relação à predisposição à seleção e compra de produtos de uma empresa que administra campanhas de divulgação pela Internet para venda por atacado. As cidades foram divididas em três grupos conforme o número de habitantes e as principais métricas de performance das campanhas online foram comparadas entre os grupos através de análises de estatísticas descritivas, ANOVA e testes post hoc. Os grupos apresentaram diferenças estatisticamente significativas entre si em todas as etapas do processo de busca e compra. A principal diferença encontrada foi no momento em que os usuários preencheram cadastros no site, demonstrando interesse nos produtos. Nesta etapa, os consumidores de municípios de menor porte se cadastraram proporcionalmente mais do que o dobro dos de cidades de porte intermediário e mais de três vezes em relação ao grupo das maiores, o que impactou diretamente no custo por venda realizada e nas taxas absolutas de vendas. / The Internet has been changing the way people buy and search for new products. In places where the assortment in brick-and-mortar stores is restricted, online channels may represent a significant change in the landscape, due to the fact that they carry virtually unlimited offers. The aim of this study is to analyze the influence of the number of inhabitants of a city on their likelihood of selecting and purchasing products from a company which runs online marketing campaigns for resellers. The cities were divided in three groups according to the population size. In addition, the main metrics for online campaigns were compared among groups through descriptive statistics, ANOVAs and pot hoc tests. There was a statistically significant difference among the groups in all steps of the search and purchase process. The main difference was found when the users fill in the forms in the website, demonstrating interest in the product. In this stage, customers from smaller cities showed a registering rate which was more than twice as much higher than the medium-sized cities group and more than three times the amount of the larger cities group, which led to a direct impact on the cost-per-sale and absolute sales rates.

A Internet vem transformando a maneira como as pessoas compram e buscam por informações sobre produtos. Para locais onde as ofertas físicas apresentam algum tipo de restrição, os canais online podem trazer mudanças ainda mais significativas, já que oferecem aos consumidores um sortimento virtualmente ilimitado. O objetivo deste trabalho foi o de analisar a influência do número de habitantes de uma cidade em relação à predisposição à seleção e compra de produtos de uma empresa que administra campanhas de divulgação pela Internet para venda por atacado. As cidades foram divididas em três grupos conforme o número de habitantes e as principais métricas de performance das campanhas online foram comparadas entre os grupos através de análises de estatísticas descritivas, ANOVA e testes post hoc. Os grupos apresentaram diferenças estatisticamente significativas entre si em todas as etapas do processo de busca e compra. A principal diferença encontrada foi no momento em que os usuários preencheram cadastros no site, demonstrando interesse nos produtos. Nesta etapa, os consumidores de municípios de menor porte se cadastraram proporcionalmente mais do que o dobro dos de cidades de porte intermediário e mais de três vezes em relação ao grupo das maiores, o que impactou diretamente no custo por venda realizada e nas taxas absolutas de vendas. / The Internet has been changing the way people buy and search for new products. In places where the assortment in brick-and-mortar stores is restricted, online channels may represent a significant change in the landscape, due to the fact that they carry virtually unlimited offers. The aim of this study is to analyze the influence of the number of inhabitants of a city on their likelihood of selecting and purchasing products from a company which runs online marketing campaigns for resellers. The cities were divided in three groups according to the population size. In addition, the main metrics for online campaigns were compared among groups through descriptive statistics, ANOVAs and pot hoc tests. There was a statistically significant difference among the groups in all steps of the search and purchase process. The main difference was found when the users fill in the forms in the website, demonstrating interest in the product. In this stage, customers from smaller cities showed a registering rate which was more than twice as much higher than the medium-sized cities group and more than three times the amount of the larger cities group, which led to a direct impact on the cost-per-sale and absolute sales rates.

本研究主旨是從人力資本理論以及勞動市場條件的觀點，來探討原、漢族群的工資不平等之現象根源。長久以來，原住民從成長、學校教育，到進入職場，莫不受各種條件的不足所制，以至於與主流社會的社經處境有難以克服的落差。本研究採用2007年「社會變遷基本調查第五期第三次」階層組以及休閒組調查，和2007年「臺灣原住民社會變遷與政策評估調查研究」，三筆具代表性且規模相近的面訪資料、共2393位私部門受雇者來加以比較。透過群體加權校正，本研究首先透過多元迴歸與交互作用分析，來探討兩族群的人力資本和勞動市場條件與工資取得高低之間的關係。接著，再以經Heckman校正Blinder-Oaxaca差異分解，來分析兩族群工資落差中的結構與現象差異。 研究結果顯示，人力資本和勞動市場條件能說明原住民族與漢人之間，確有工資上的族群歧視現象。原住民教育的工資報酬率在義務教育階段後即無顯著效果，而不同於漢人能持續成長；不論是年資、職業聲望或是工作型態，原住民的工資報酬率都顯著也比漢人低落，且影響更勝教育差異。這些現象即使是在差異分解校正結構差異後依舊存在。是故，既有量化研究除了從教育面向來探討原、漢族群社經不平等之外，實應持續重視原住民族進入職場後，所面對的勞動市場問題。 / The aim of this research is to study the wage gap between aborigines and Han Chinese in Taiwan. The research explores the impacts of human capital and labor market conditions on the wage gap. Throughuot the life course trajectories of schooling and labor market participation, aborigines in Taiwan persistently face dire straits, resulting in insurmountable soci-economic gaps with Han Chinese. The data sources of the research are from Taiwan Social Changy Survey (TSCS) 2007, Phase 5, Wave 3: The Social Stratification module and The Leisure Time module, and Social Change and Policy of Taiwanese Indigenous Peoples Survey (TIPS) 2007, which are representative to the adult population in Taiwan. The total sample sizes are 2393 employees in private sector and roughly equal in size between two ethnics. With weighting, regression interaction effects were estimated to analyze the impacts of human capital and labor market conditions on wage differences between aborigines and Han Chinese. Moreover, the research uses two-steps Heckman selection model to correct selection bias of labor marke participation as well as Blinder-Oaxaca decomposition to analyze the ethnic disparities in wage. The finding of interaction models show that human capital and labor market conditions can explain the wage gap and reveal the negative effects of discrimination against aborigines. While only the compulsory education has positive effects on aborigines’ wage, Han Chinese could benefit from all stage of education. Job tenures, occupational prestiage, and employment types are more benefitical to Han Chinese than to aborigines, and the impacts of these factors on wage are greater than education. These results are also consistent with decomposition analysis. Other than education inequality, the finding of this research suggests that future studies of ethnic disparities in soci-economic inequality should concern more about ethnic differences in labor market conditons.

L'IRM de diffusion (IRMd) est une modalité d'imagerie qui permet d'étudier in vivo la structure des faisceaux de la substance blanche grâce à la caractérisation des propriétés de diffusion des molécules d'eau dans le cerveau. Les travaux de cette thèse se sont concentrés sur la comparaison de groupes d'individus en IRMd. Le but est d'identifier les zones de la substance blanche dont les propriétés structurelles sont statistiquement différentes entre les deux populations ou significativement corrélées avec certaines variables explicatives. L’enjeu est de pouvoir localiser et caractériser les lésions causées par une pathologie et de comprendre les mécanismes sous-jacents. Pour ce faire, nous avons proposé dans cette thèse des méthodes d'analyse basées voxel reposant sur le Modèle Linéaire Général (MLG) et ses extensions multivariées et sur des variétés, qui permettent d'effectuer des tests statistiques intégrant explicitement des variables explicatives. En IRMd, la diffusion des molécules d'eau peut être modélisée par un tenseur d'ordre deux représenté par une matrice symétrique définie-positive de dimension trois. La principale contribution de cette thèse a été de montrer la plus-value de considérer, dans le MLG, l'information complète du tenseur par rapport à un unique descripteur scalaire caractérisant la diffusion (fraction d’anisotropie ou diffusion moyenne), comme cela est généralement fait dans les études en neuro-imagerie. Plusieurs stratégies d’extension du MLG aux tenseurs ont été comparées, que ce soit en termes d’hypothèse statistique (homoscédasticité vs hétéroscédasticité), de métrique utilisée pour l’estimation des paramètres (Euclidienne, Log-Euclidienne et Riemannienne), ou de prise en compte de l’information du voisinage spatial. Nous avons également étudié l'influence de certains prétraitements comme le filtrage et le recalage. Enfin, nous avons proposé une méthode de caractérisation des zones détectées afin d’en faciliter l’interprétation physiopathologique. Les validations ont été menées sur données synthétiques ainsi que sur une base d’images issues d’une cohorte de patients atteints de Neuromyélite optique de Devic. / Diffusion Tensor MRI (DT-MRI) is an imaging modality that allows to study in vivo the structure of white matter fibers through the characterization of diffusion properties of water molecules in the brain. This work focused on group comparison in DT-MRI. The aim is to identify white matter regions whose structural properties are statistically different between two populations or significantly correlated with some explanatory variables. The challenge is to locate and characterize lesions caused by a disease and to understand the underlying mechanisms. To this end, we proposed several voxel-based strategies that rely on the General Linear Model (GLM) and its multivariate and manifold-based extensions, to perform statistical tests that explicitly incorporate explanatory variables. In DT-MRI, diffusion of water molecules can be modeled by a second order tensor represented by a three dimensional symmetric and positive definite matrix. The main contribution of this thesis was to demonstrate the added value of considering the full tensor information as compared to a single scalar index characterizing some diffusion properties (fractional anisotropy or mean diffusion) in the GLM, as it is usually done in neuroimaging studies. Several strategies for extending the GLM to tensor were compared, either in terms of statistical hypothesis (homoscedasticity vs heteroscedasticity), or metrics used for parameter estimation (Euclidean, Log-Euclidean and Riemannian), or the way to take into account the spatial neighborhood information. We also studied the influence of some pre-processing such as filtering and registration. Finally, we proposed a method for characterizing the detected regions in order to facilitate their physiopathological interpretation. Validations have been conducted on synthetic data as well as on a cohort of patients suffering from Neuromyelitis Optica.

L'analyse des changements morphologiques du cerveau dans des séries temporelles d'images est un sujet important en neuroimagerie. Bien que le développement des bases de données longitudinales ait aidé à réduire la variabilité inter-individu, il reste encore de nombreux biais qui doivent être évités lors de l'estimation des évolutions longitudinales. De plus, lorsque les changements intra-sujet sont très faibles par rapport à la variabilité inter-sujet, il est crucial de savoir si les méthodes existantes peuvent capturer sans biais les changements longitudinaux. Dans la plupart des études, les changements longitudinaux sont limités à leur composante volumétrique scalaire afin d'en faciliter l'analyse. Cependant, les changements cérébraux ne sont généralement pas uniquement volumétriques et dans ce cas multivarié, l'interprétation est alors plus difficile. Cette thèse adresse ces problèmes en suivant trois axes principaux. Premièrement, nous proposons une chaîne de traitement longitudinale reposant sur la morphométrie à partir de déformations et ayant pour but d'estimer de manière robuste les changements longitudinaux. Afin d’éviter de rajouter du biais, nous détaillons tout l'enchaînement des étapes de traitement. En plus de cette contribution, nous intégrons une modification de l'algorithme de recalage non-linéaire qui consiste à masquer le terme de similarité tout en conservant la symétrie de la formulation. Cette contribution augmente la robustesse des résultats vis-à-vis des artefacts d'intensité situés en bordure du cerveau et augmente ainsi la sensibilité de l'étude statistique réalisée sur les déformations longitudinales / Analysing the progression of brain morphological changes in time series of images is an important topic in neuroimaging. Although the development of longitudinal databases has helped reducing the inter-individual variability, there still exist numerous biases that need to be avoided when capturing longitudinal evolutions. Moreover, when the intra-subject changes are very small with respect to the inter-subject variability it is crucial to know if the available methods can capture the longitudinal change with no bias. In most of the studies, these longitudinal changes are limited to scalar volumetric changes in order to ease their analysis. However, one can observe that brain changes are not limited to volumetry. In this multivariate case, the interpretation is more difficult. This thesis addresses these problems along three main axes. First, we propose a longitudinal Deformation-based Morphometry processing pipeline to robustly estimate the longitudinal changes. We detail the whole sequencing of the processing steps as they are key to avoid adding bias. In addition to this contribution we integrate a modification to the non-linear registration algorithm by masking the similarity term while keeping the symmetry of the formulation. This change increases the robustness of the results with respect to intensity artifacts located in the brain boundaries and leads to increased sensitivity of the statistical study on the longitudinal deformations. The proposed processing pipeline is based on freely available software and tools so that it is fully reproducible