Dissertations / Theses: 'Multivariate analysis of variance MANOVA'

1

Rogers, Catherine Jane. "Power comparisons of four post-MANOVA tests under variance-covariance heterogeneity and non-normality in the two group case." Diss., Virginia Tech, 1994. http://hdl.handle.net/10919/40171.

Full text

APA, Harvard, Vancouver, ISO, and other styles

2

Sartorio, Simone Daniela. "Aplicações de técnicas de análise multivariada em experimentos agropecuários usando o software R." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/11/11134/tde-06082008-172655/.

Full text

Abstract:

O uso das técnicas de análise multivariada está reservado aos grandes centros de pesquisa, µas grandes empresas e ao ambiente acad^emico. Essas técnicas s~ao muito interessantes porque utilizam simultaneamente todas as variáveis respostas na interpretação teórica do conjunto de dados, levando em conta as correlações existentes entre elas. Uma das principais barreiras para a utilização dessas técnicas é o seu desconhecimento pelos pesquisadores interessados na pesquisa quantitativa. A outra dificuldade é que a grande maioria de softwares que permitem esse tipo de análise (SAS, MINITAB, BMDP, STATISTICA, S-PLUS, SYSTAT, etc.) não são de domínio público. A disseminação do uso das técnicas multivariadas pode melhorar a qualidade das pesquisas, proporcionar uma economia relativa de tempo e de custo, e facilitar a interpretação das estruturas dos dados, diminuindo a perda de informação. Neste trabalho, foram confirmadas algumas vantagens das técnicas multivariadas sobre as univariadas na análise de dados de expe- rimentos agropecuários. As análises foram realizadas com o auxílio do software R, um software aberto, \"amigável\" e gratuito, com inúmeros recursos disponíveis.
The use of the techniques of multivariate analysis is restricted to large centers of research, the higher companies and the academic environment. These techniques are very inte- resting because of the use of all answers variables simultaneously in theoretical interpretation of the data set, considering the correlations between them. One of the main obstacle to the usage of these techniques is that researchers interested in the quantitative research do not know them. The other di±culty is that most of the software that allow this type of analysis (SAS, MINITAB, BMDP, STATISTICA, S-PLUS, SYSTAT etc.) are not in public domain. Publishing the use of Multivariate techniques can improve the quality of the research, decrease the time spend and the cost, and make easy the interpretation of the structures of the data without cause damage of the information. In this report, were con¯rmed some advantages of the multivariate techniques in a univariate analysis for data of agricultural experiments. The analysis were taken with R software, a open software, \"friendly\" and free, with many statistical resources available.

APA, Harvard, Vancouver, ISO, and other styles

3

Ao, Xiang. "The cross-cultural leader a comparative study of leadership behaviours in China and New Zealand : a thesis submitted to Auckland University of Technology in fulfillment of the requirements for the degree of Master of Philosophy, August 2008." Click here to access this resource online, 2008. http://hdl.handle.net/10292/444.

Full text

Abstract:

National cultures play a critical role in effective leadership and organisational success in international businesses. Contemporary organisations are therefore challenged by cross-cultural leadership needs to address increasing diversity. In the past decades, there has been a growing interest in studies of non-Western leadership. Recent papers have focused particularly on leadership in the Asia-Pacific region. This paper compares leadership in China and New Zealand, based on the data collected by using the GLOBE (Global Leadership and Organisational Behaviour Effectiveness) project leadership questionnaire. In addition, the paper reviews the main findings of previous research in order to investigate the similarities and differences in preferred leadership behaviours/characteristics in both cultures, while attempting to examine the consistency of current findings against the previous GLOBE studies. Significant differences of leadership behaviours between China and New Zealand have been identified. This paper generally supports the findings of previous GLOBE studies that charismatic/value-based leadership is the universally contributing factor towards outstanding leadership and self-protective leadership is the universally negative factor against leadership excellence. Findings in this paper may contribute to further understanding of leadership practice in these two countries. Future research should be undertaken to examine the effects of cultural differences on organisational practice by a more comprehensive research method.

APA, Harvard, Vancouver, ISO, and other styles

4

Basaran, Seren. "An Exploration Of Affective And Demographic Factors That Are Related To Mathematical Thinking And Reasoning Of University Students." Phd thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613422/index.pdf.

Full text

Abstract:

There are four major aims of this study: Firstly, factors regarding university students&rsquo
approaches to studying, self-efficacy in mathematics, problem solving strategies, demographic profile, mathematical thinking and reasoning competencies were identified through the adopted survey and the competency test which was designed by the researcher. These scales were administered to 431 undergraduate students of mathematics, elementary and secondary mathematics education in Ankara and in Northern Cyprus and to prospective teachers of classroom teacher and early childhood education of teacher training academy in Northern Cyprus. Secondly, three structural models were proposed to explore the interrelationships among idenitified factors. Thirdly, among three models, the model yielding best fit to data was selected to evaluate the equality of the factor structure across Ankara and Northern Cyprus regions. Lastly, differences regarding pre-identified factors with respect to gender, region and grade level separately and dual, triple interaction effects were investigated through two two-way MANOVA and a three-way ANOVA analyses. Exploratory and confirmatory factor analyses were employed to determine the factors
meaning orientation, mathematics self-efficacy, motivation, disorganized study methods and surface approach for the survey and &lsquo
expressing, extracting and computing mathematically&rsquo
(fundamental skills) and &lsquo
logical inferencing and evaluating conditional statements in real life situations&rsquo
(elaborate skills) for the test. The three models commonly revealed that while mathematics self-efficacy has a significant positive effect on both fundamental and elaborate skills, motivation which is a combination of intrinsic, extrinsic and achievement motivational items was found to have a negative direct impact on fundamental skills and has a negative indirect contribution upon elaborate skills. The results generally support the invariance of the tested factor structure across two regions with some evidence of differences. Ankara region sample yielded similar factor structure to that of the entire sample&rsquo
s results whereas
no significant relationships were observed for Northern Cyprus region sample. Results of gender, grade level and region related differences in the factors of the survey and the test and on the total test indicated that, females are more meaning oriented than males. &lsquo
Fourth and fifth (senior)&rsquo
and third year university students use disorganized study methods more often than second year undergraduate students. In addition, senior students are more competent than second and third year undergraduate students in terms of both skills. Freshmen students outscored sophomore students in the elaborate skills. Students from Ankara region are more competent in terms of both skills than students from Northern Cyprus region. This last inference is also valid on the total test score for both regions. Males performed better on the total test than females. Moreover, there exist region and grade level interaction effect upon both skills. Additionally, significant interaction effects of &lsquo
region and gender&rsquo
, &lsquo
region and grade level&rsquo
, &lsquo
gender and grade level&rsquo
and &lsquo
region and gender and grade level&rsquo
were detected upon the total test score.

APA, Harvard, Vancouver, ISO, and other styles

5

Nisa, Khoirin. "On multivariate dispersion analysis." Thesis, Besançon, 2016. http://www.theses.fr/2016BESA2025.

Full text

Abstract:

Cette thèse examine la dispersion multivariée des modelés normales stables Tweedie. Trois estimateurs de fonction variance généralisée sont discutés. Ensuite dans le cadre de la famille exponentielle naturelle deux caractérisations du modèle normal-Poisson, qui est un cas particulier de modèles normales stables Tweedie avec composante discrète, sont indiquées : d'abord par fonction variance et ensuite par fonction variance généralisée. Le dernier fournit la solution à un problème particulier d'équation de Monge-Ampère. Enfin, pour illustrer l'application de la variance généralisée des modèles Tweedie stables normales, des exemples à partir des données réelles sont fournis
This thesis examines the multivariate dispersion of normal stable Tweedie (NST) models. Three generalize variance estimators of some NST models are discussed. Then within the framework of natural exponential family, two characterizations of normal Poisson model, which is a special case of NST models with discrete component, are shown : first by variance function and then by generalized variance function. The latter provides a solution to a particular Monge-Ampere equation problem. Finally, to illustrate the application of generalized variance of normal stable Tweedie models, examples from real data are provided

APA, Harvard, Vancouver, ISO, and other styles

6

Prosser, Robert James. "Robustness of multivariate mixed model ANOVA." Thesis, University of British Columbia, 1985. http://hdl.handle.net/2429/25511.

Full text

Abstract:

In experimental or quasi-experimental studies in which a repeated measures design is used, it is common to obtain scores on several dependent variables on each measurement occasion. Multivariate mixed model (MMM) analysis of variance (Thomas, 1983) is a recently developed alternative to the MANOVA procedure (Bock, 1975; Timm, 1980) for testing multivariate hypotheses concerning effects of a repeated factor (called occasions in this study) and interaction between repeated and non-repeated factors (termed group-by-occasion interaction here). If a condition derived by Thomas (1983), multivariate multi-sample sphericity (MMS), regarding the equality and structure of orthonormalized population covariance matrices is satisfied (given multivariate normality and independence for distributions of subjects' scores), valid likelihood-ratio MMM tests of group-by-occasion interaction and occasions hypotheses are possible. To date, no information has been available concerning actual (empirical) levels of significance of such tests when the MMS condition is violated. This study was conducted to begin to provide such information. Departure from the MMS condition can be classified into three types— termed departures of types A, B, and C respectively: (A) the covariance matrix for population ℊ (ℊ = 1,...G), when orthonormalized, has an equal-diagonal-block form but the resulting matrix for population ℊ is unequal to the resulting matrix for population ℊ' (ℊ ≠ ℊ'); (B) the G populations' orthonormalized covariance matrices are equal, but the matrix common to the populations does not have equal-diagonal-block structure; or (C) one or more populations has an orthonormalized covariance matrix which does not have equal-diagonal-block structure and two or more populations have unequal orthonormalized matrices. In this study, Monte Carlo procedures were used to examine the effect of each type of violation in turn on the Type I error rates of multivariate mixed model tests of group-by-occasion interaction and occasions null hypotheses. For each form of violation, experiments modelling several levels of severity were simulated. In these experiments: (a) the number of measured variables was two; (b) the number of measurement occasions was three; (c) the number of populations sampled was two or three; (d) the ratio of average sample size to number of measured variables was six or 12; and (e) the sample size ratios were 1:1 and 1:2 when G was two, and 1:1:1 and 1:1:2 when G was three. In experiments modelling violations of types A and C, the effects of negative and positive sampling were studied. When type A violations were modelled and samples were equal in size, actual Type I error rates did not differ significantly from nominal levels for tests of either hypothesis except under the most severe level of violation. In type A experiments using unequal groups in which the largest sample was drawn from the population whose orthogonalized covariance matrix has the smallest determinant (negative sampling), actual Type I error rates were significantly higher than nominal rates for tests of both hypotheses and for all levels of violation. In contrast, empirical levels of significance were significantly lower than nominal rates in type A experiments in which the largest sample was drawn from the population whose orthonormalized covariance matrix had the largest determinant (positive sampling). Tests of both hypotheses tended to be liberal in experiments which modelled type B violations. No strong relationships were observed between actual Type I error rates and any of: severity of violation, number of groups, ratio of average sample size to number of variables, and relative sizes of samples. In equal-groups experiments modelling type C violations in which the orthonormalized pooled covariance matrix departed at the more severe level from equal-diagonal-block form, actual Type I error rates for tests of both hypotheses tended to be liberal. Findings were more complex under the less severe level of structural departure. Empirical significance levels did not vary with the degree of interpopulation heterogeneity of orthonormalized covariance matrices. In type C experiments modelling negative sampling, tests of both hypotheses tended to be liberal. Degree of structural departure did not appear to influence actual Type I error rates but degree of interpopulation heterogeneity did. Actual Type I error rates in type C experiments modelling positive sampling were apparently related to the number of groups. When two populations were sampled, both tests tended to be conservative, while for three groups, the results were more complex. In general, under all types of violation the ratio of average group size to number of variables did not greatly affect actual Type I error rates. The report concludes with suggestions for practitioners considering use of the MMM procedure based upon the findings and recommends four avenues for future research on Type I error robustness of MMM analysis of variance. The matrix pool and computer programs used in the simulations are included in appendices.
Education, Faculty of
Educational and Counselling Psychology, and Special Education (ECPS), Department of
Graduate

APA, Harvard, Vancouver, ISO, and other styles

7

Kong, Xiaoli. "High Dimensional Multivariate Inference Under General Conditions." UKnowledge, 2018. https://uknowledge.uky.edu/statistics_etds/33.

Full text

Abstract:

In this dissertation, we investigate four distinct and interrelated problems for high-dimensional inference of mean vectors in multi-groups. The first problem concerned is the profile analysis of high dimensional repeated measures. We introduce new test statistics and derive its asymptotic distribution under normality for equal as well as unequal covariance cases. Our derivations of the asymptotic distributions mimic that of Central Limit Theorem with some important peculiarities addressed with sufficient rigor. We also derive consistent and unbiased estimators of the asymptotic variances for equal and unequal covariance cases respectively. The second problem considered is the accurate inference for high-dimensional repeated measures in factorial designs as well as any comparisons among the cell means. We derive asymptotic expansion for the null distributions and the quantiles of a suitable test statistic under normality. We also derive the estimator of parameters contained in the approximate distribution with second-order consistency. The most important contribution is high accuracy of the methods, in the sense that p-values are accurate up to the second order in sample size as well as in dimension. The third problem pertains to the high-dimensional inference under non-normality. We relax the commonly imposed dependence conditions which has become a standard assumption in high dimensional inference. With the relaxed conditions, the scope of applicability of the results broadens. The fourth problem investigated pertains to a fully nonparametric rank-based comparison of high-dimensional populations. To develop the theory in this context, we prove a novel result for studying the asymptotic behavior of quadratic forms in ranks. The simulation studies provide evidence that our methods perform reasonably well in the high-dimensional situation. Real data from Electroencephalograph (EEG) study of alcoholic and control subjects is analyzed to illustrate the application of the results.

APA, Harvard, Vancouver, ISO, and other styles

8

Yockey, Ron David. "An investigation of the type I error rates and power of standard and alternative multivariate tests on means under homogeneous and heterogeneous covariance matrices and multivariate normality and nonnormality /." Full text (PDF) from UMI/Dissertation Abstracts International, 2000. http://wwwlib.umi.com/cr/utexas/fullcit?p9992945.

Full text

APA, Harvard, Vancouver, ISO, and other styles

9

Nqabeni, Luxolo. "Development of an antiretroviral solid dosage form using multivariate analysis." Thesis, Nelson Mandela Metropolitan University, 2007. http://hdl.handle.net/10948/705.

Full text

Abstract:

The aim of pharmaceutical development is to design a quality product and the manufacturing process to deliver the product in a reproducible manner. The development of a new and generic formulation is based on a large number of experiments. Statistics provides many tools for studying the conditions of formulations and processes and enables us to optimize the same while being able to minimize our experimentation. The purpose of this study was to apply experimental design methodology (DOE) and multivariate analysis to the development and optimization of tablet formulations containing 150 mg lamivudine manufactured by direct compression.

APA, Harvard, Vancouver, ISO, and other styles

10

Wardak, Mohammad Alif. "Survival analysis." CSUSB ScholarWorks, 2005. https://scholarworks.lib.csusb.edu/etd-project/2810.

Full text

Abstract:

Survival analysis pertains to a statistical approach designed to take into account the amount of time an experimental unit contributes to a study. A Mayo Clinic study of 418 Primary Biliary Cirrhosis patients during a ten year period was used. The Kaplan-Meier Estimator, a non-parametric statistic, and the Cox Proportional Hazard methods were the tools applied. Kaplan-Meier results include total values/censored values.

APA, Harvard, Vancouver, ISO, and other styles

11

Shi, Minggao. "Multivariate analysis of variance and robust estimation of covariance structures when the data are curves /." The Ohio State University, 1993. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487846885778564.

Full text

APA, Harvard, Vancouver, ISO, and other styles

12

Morris, Nathan J. "Multivariate and Structural Equation Models for Family Data." Case Western Reserve University School of Graduate Studies / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=case1247004562.

Full text

APA, Harvard, Vancouver, ISO, and other styles

13

Cho, Gyo-Young. "Multivariate control charts for the mean vector and variance-covariance matrix with variable sampling intervals." Diss., Virginia Tech, 1991. http://hdl.handle.net/10919/37242.

Full text

APA, Harvard, Vancouver, ISO, and other styles

14

Ho, Kwok Wah. "RJMCMC algorithm for multivariate Gaussian mixtures with applications in linear mixed-effects models /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?ISMT%202005%20HO.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Safari, Katesari Hadi. "BAYESIAN DYNAMIC FACTOR ANALYSIS AND COPULA-BASED MODELS FOR MIXED DATA." OpenSIUC, 2021. https://opensiuc.lib.siu.edu/dissertations/1948.

Full text

Abstract:

Available statistical methodologies focus more on accommodating continuous variables, however recently dealing with count data has received high interest in the statistical literature. In this dissertation, we propose some statistical approaches to investigate linear and nonlinear dependencies between two discrete random variables, or between a discrete and continuous random variables. Copula functions are powerful tools for modeling dependencies between random variables. We derive copula-based population version of Spearman’s rho when at least one of the marginal distribution is discrete. In each case, the functional relationship between Kendall’s tau and Spearman’s rho is obtained. The asymptotic distributions of the proposed estimators of these association measures are derived and their corresponding confidence intervals are constructed, and tests of independence are derived. Then, we propose a Bayesian copula factor autoregressive model for time series mixed data. This model assumes conditional independence and shares latent factors in both mixed-type response and multivariate predictor variables of the time series through a quadratic timeseries regression model. This model is able to reduce the dimensionality by accommodating latent factors in both response and predictor variables of the high-dimensional time series data. A semiparametric time series extended rank likelihood technique is applied to the marginal distributions to handle mixed-type predictors of the high-dimensional time series, which decreases the number of estimated parameters and provides an efficient computational algorithm. In order to update and compute the posterior distributions of the latent factors and other parameters of the models, we propose a naive Bayesian algorithm with Metropolis-Hasting and Forward Filtering Backward Sampling methods. We evaluate the performance of the proposed models and methods through simulation studies. Finally, each proposed model is applied to a real dataset.

APA, Harvard, Vancouver, ISO, and other styles

16

Pontes, Antonio Carlos Fonseca. "Análise de variância multivariada com a utilização de testes não -paramétricos e componentes principais baseados em matrizes de postos." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/11/11134/tde-09082005-123633/.

Full text

Abstract:

Métodos não-paramétricos têm aplicação ampla na análise de dados, tendo em vista que não são limitados pela necessidade de imposição de distribuições populacionais específicas. O caráter multivariado de dados provenientes de estudos nas ciências do comportamento, ecológicos, experimentos agrícolas e muitos outros tipos, e o crescimento contínuo da tecnologia computacional, têm levado a um crescente interesse no uso de métodos multivariados não-paramétricos. A aplicação da análise de variância multivariada não-paramétrica é pouco inacessível ao pesquisador, exceto através de métodos aproximados baseados nos valores assintóticos da estatística de teste. Portanto, este trabalho tem por objetivo apresentar uma rotina na linguagem C que realiza testes baseados numa extensão multivariada do teste univariado de Kruskal- Wallis, usando a técnica das permutações. Para pequenas amostras, todas as configurações de tratamentos são obtidas para o cálculo do valor-p. Para grandes amostras, um número fixo de configurações aleatórias é usado, obtendo assim valores de significância aproximados. Além disso, um teste alternativo é apresentado com o uso de componentes principais baseados nas matrizes de postos.
Nonparametric methods have especially broad applications in the analysis of data since they are not bound by restrictions on the population distribution. The multivariate character of behavioural, ecological, agricultural and many other types of data and the continued improvement in computer technology have led to a sharp interest in the use of nonparametric multivariate methods in data analysis. The application of nonparametric multivariate analysis is inaccessible to applied research, except by approximation methods based on asymptotic values of the test statistic. Thus, this work aims to presenting a routine in the C language that runs multivariate tests based on a multivariate extension of the univariate Kruskal-Wallis test, using permutation technique. For small samples, all possible treatment configurations are used in order to obtain the p-value. For large samples, a fixed number of random configurations are used, obtaining an approximated significance values. In addition, another alternative test is presented using principal components based on rank matrices.

APA, Harvard, Vancouver, ISO, and other styles

17

Messetti, Ana Vergínia Libos [UNESP]. "Utilização de técnicas multivariadas na avaliação da divergência genética de populações de girassol (Helianthus annuus L.)." Universidade Estadual Paulista (UNESP), 2007. http://hdl.handle.net/11449/101858.

Full text

Abstract:

Made available in DSpace on 2014-06-11T19:31:37Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-06-01Bitstream added on 2014-06-13T19:41:57Z : No. of bitstreams: 1 messetti_avl_dr_botfca.pdf: 1122280 bytes, checksum: 539d4ccf859c8ac755f6adba3eeb14de (MD5)
Este trabalho foi desenvolvido com os objetivos de avaliar a divergência genética de 12 populações de girassol do Banco de Germoplasma da EMBRAPA /Soja de Londrina por meio de técnicas multivariadas; divulgar tópicos recentes e interessantes das técnicas multivariadas que não são explorados nos trabalhos científicos de melhoramento de plantas e orientar a escolha de populações para cruzamentos nos programas de melhoramento genético da cultura de girassol. O modelo experimental constitui-se de delineamento bloco casualizado envolvendo 12 variedades de girassol avaliadas sob cinco caracteres morfoagronômicos. Por meio da análise univariada foi verificada diferença significativa (p<0,05) dos tratamentos para todos caracteres. A aplicação dos componentes principais permitiu a redução bidimensional, com a explicação de 82,5% da variação total. O número de componentes foi avaliado pelo critério de Kaiser e critério Scree-test. A visualização da divergência genética proporcionada pelos escores das duas primeiras variáveis canônicas, evidenciaram grupos geneticamente diferentes. Ambas técnicas apontaram concordância nos resultados. Com base nas estimativas da distância Mahalanobis e distância euclideana foi realizada a análise de agrupamento adotando-se três algoritmos hierárquicos. Para determinar o número de grupos adotou-se o dendrograma, a análise do nível de fusão e a análise do comportamento de similaridade. Para validação utilizou-se o critério de Wilks dentro de cada grupo e gráficos multivariados auxiliaram na interpretação dos resultados. Pode-se concluir pela existência da divergência genética, detectando-se quatro grupos geneticamente diferentes e caracterizado pelos escores médios.
The objective of this work was to evaluate genetic divergence in 12 sunflower populations from EMBRAPA/ Londrina Soybean Germplasm Bank, using multivariate techniques, to discuss recent and interesting topics related to the multivariate techniques donþt found in plant improvement scientific papers, and to offer guidelines on how to choose populations for sunflower genetic improvement crossing programs. The experiment included a totally block casualized design, with twelve sunflower varieties, evaluated according to 5 morphoagronomics traits. The univariate analysis showed a significant difference (p<0,05) among treatments for all the traits. Application of main components allowed for a bi-dimensional reduction, with 82,5% of the total variation. The number of components were evaluated by the Kaiser and Scree-test criteria. Genetic divergence visualization provided by the two first canonical variables showed genetically different groups. Both techniques showed the same results. Based on Mahalanobis and Euclidean distance estimates, a clustering analysis was carried out using three hierarchicals algorithms. A dendrogram, a fusion level analysis and a similarity behavior analysis were conducted to determine the number of groups. Validation used the Wilks criteria inside each group, while multivariate graphs helped with data interpretation. Results from this study showed genetic divergence in four groups characterized by average/mean scores.

APA, Harvard, Vancouver, ISO, and other styles

18

Messetti, Ana Vergínia Libos 1964. "Utilização de técnicas multivariadas na avaliação da divergência genética de populações de girassol (Helianthus annuus L.) /." Botucatu : [s.n.], 2007. http://hdl.handle.net/11449/101858.

Full text

Abstract:

Orientador: Carlos Roberto Padovani
Banca: Adriano Wagner Ballarin
Banca: José Carlos Martinez
Banca: Jacinta Ludovico Zamboti
Banca: Marie Oshiiwa
Resumo: Este trabalho foi desenvolvido com os objetivos de avaliar a divergência genética de 12 populações de girassol do Banco de Germoplasma da EMBRAPA /Soja de Londrina por meio de técnicas multivariadas; divulgar tópicos recentes e interessantes das técnicas multivariadas que não são explorados nos trabalhos científicos de melhoramento de plantas e orientar a escolha de populações para cruzamentos nos programas de melhoramento genético da cultura de girassol. O modelo experimental constitui-se de delineamento bloco casualizado envolvendo 12 variedades de girassol avaliadas sob cinco caracteres morfoagronômicos. Por meio da análise univariada foi verificada diferença significativa (p<0,05) dos tratamentos para todos caracteres. A aplicação dos componentes principais permitiu a redução bidimensional, com a explicação de 82,5% da variação total. O número de componentes foi avaliado pelo critério de Kaiser e critério Scree-test. A visualização da divergência genética proporcionada pelos escores das duas primeiras variáveis canônicas, evidenciaram grupos geneticamente diferentes. Ambas técnicas apontaram concordância nos resultados. Com base nas estimativas da distância Mahalanobis e distância euclideana foi realizada a análise de agrupamento adotando-se três algoritmos hierárquicos. Para determinar o número de grupos adotou-se o dendrograma, a análise do nível de fusão e a análise do comportamento de similaridade. Para validação utilizou-se o critério de Wilks dentro de cada grupo e gráficos multivariados auxiliaram na interpretação dos resultados. Pode-se concluir pela existência da divergência genética, detectando-se quatro grupos geneticamente diferentes e caracterizado pelos escores médios.
Abstract: The objective of this work was to evaluate genetic divergence in 12 sunflower populations from EMBRAPA/ Londrina Soybean Germplasm Bank, using multivariate techniques, to discuss recent and interesting topics related to the multivariate techniques donþt found in plant improvement scientific papers, and to offer guidelines on how to choose populations for sunflower genetic improvement crossing programs. The experiment included a totally block casualized design, with twelve sunflower varieties, evaluated according to 5 morphoagronomics traits. The univariate analysis showed a significant difference (p<0,05) among treatments for all the traits. Application of main components allowed for a bi-dimensional reduction, with 82,5% of the total variation. The number of components were evaluated by the Kaiser and Scree-test criteria. Genetic divergence visualization provided by the two first canonical variables showed genetically different groups. Both techniques showed the same results. Based on Mahalanobis and Euclidean distance estimates, a clustering analysis was carried out using three hierarchicals algorithms. A dendrogram, a fusion level analysis and a similarity behavior analysis were conducted to determine the number of groups. Validation used the Wilks criteria inside each group, while multivariate graphs helped with data interpretation. Results from this study showed genetic divergence in four groups characterized by average/mean scores.
Doutor

APA, Harvard, Vancouver, ISO, and other styles

19

Castellanos, Lucia. "Statistical Models and Algorithms for Studying Hand and Finger Kinematics and their Neural Mechanisms." Research Showcase @ CMU, 2013. http://repository.cmu.edu/dissertations/273.

Full text

Abstract:

The primate hand, a biomechanical structure with over twenty kinematic degrees of freedom, has an elaborate anatomical architecture. Although the hand requires complex, coordinated neural control, it endows its owner with an astonishing range of dexterous finger movements. Despite a century of research, however, the neural mechanisms that enable finger and grasping movements in primates are largely unknown. In this thesis, we investigate statistical models of finger movement that can provide insights into the mechanics of the hand, and that can have applications in neural-motor prostheses, enabling people with limb loss to regain natural function of the hands. There are many challenges associated with (1) the understanding and modeling of the kinematics of fingers, and (2) the mapping of intracortical neural recordings into motor commands that can be used to control a Brain-Machine Interface. These challenges include: potential nonlinearities; confounded sources of variation in experimental datasets; and dealing with high degrees of kinematic freedom. In this work we analyze kinematic and neural datasets from repeated-trial experiments of hand motion, with the following contributions: We identified static, nonlinear, low-dimensional representations of grasping finger motion, with accompanying evidence that these nonlinear representations are better than linear representations at predicting the type of object being grasped over the course of a reach-to-grasp movement. In addition, we show evidence of better encoding of these nonlinear (versus linear) representations in the firing of some neurons collected from the primary motor cortex of rhesus monkeys. A functional alignment of grasping trajectories, based on total kinetic energy, as a strategy to account for temporal variation and to exploit a repeated-trial experiment structure. An interpretable model for extracting dynamic synergies of finger motion, based on Gaussian Processes, that decomposes and reduces the dimensionality of variance in the dataset. We derive efficient algorithms for parameter estimation, show accurate reconstruction of grasping trajectories, and illustrate the interpretation of the model parameters. Sound evidence of single-neuron decoding of interpretable grasping events, plus insights about the amount of grasping information extractable from just a single neuron. The Laplace Gaussian Filter (LGF), a deterministic approximation to the posterior mean that is more accurate than Monte Carlo approximations for the same computational cost, and that in an off-line decoding task is more accurate than the standard Population Vector Algorithm.

APA, Harvard, Vancouver, ISO, and other styles

20

Olson, Brent. "Evaluating the error of measurement due to categorical scaling with a measurement invariance approach to confirmatory factor analysis." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/332.

Full text

Abstract:

It has previously been determined that using 3 or 4 points on a categorized response scale will fail to produce a continuous distribution of scores. However, there is no evidence, thus far, revealing the number of scale points that may indeed possess an approximate or sufficiently continuous distribution. This study provides the evidence to suggest the level of categorization in discrete scales that makes them directly comparable to continuous scales in terms of their measurement properties. To do this, we first introduced a novel procedure for simulating discretely scaled data that was both informed and validated through the principles of the Classical True Score Model. Second, we employed a measurement invariance (MI) approach to confirmatory factor analysis (CFA) in order to directly compare the measurement quality of continuously scaled factor models to that of discretely scaled models. The simulated design conditions of the study varied with respect to item-specific variance (low, moderate, high), random error variance (none, moderate, high), and discrete scale categorization (number of scale points ranged from 3 to 101). A population analogue approach was taken with respect to sample size (N = 10,000). We concluded that there are conditions under which response scales with 11 to 15 scale points can reproduce the measurement properties of a continuous scale. Using response scales with more than 15 points may be, for the most part, unnecessary. Scales having from 3 to 10 points introduce a significant level of measurement error, and caution should be taken when employing such scales. The implications of this research and future directions are discussed.

APA, Harvard, Vancouver, ISO, and other styles

21

Ghosh, Suvankar. "Essays on Emerging Practitioner-Relevant Theories and Methods for the Valuation of Technology." Kent State University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=kent1246573195.

Full text

APA, Harvard, Vancouver, ISO, and other styles

22

Thorne, David. "Investigating Differences in Volunteer Administrator Challenges and Management Practices." Bowling Green State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1616526934705194.

Full text

APA, Harvard, Vancouver, ISO, and other styles

23

Zanella, Andreia. "DIAGNÓSTICO DA QUALIDADE DO ENSINO-APRENDIZAGEM E SATISFAÇÃO DOS ALUNOS NAS DISCIPLINAS DE ESTATÍSTICA DA UFSM." Universidade Federal de Santa Maria, 2008. http://repositorio.ufsm.br/handle/1/8063.

Full text

Abstract:

The search for education quality has emerged so growing in recent years. It has noticed a major concern before the current educational picture by the society, government, professors and students. This study searched to evaluate the satisfaction of the students of the Department of Statistics of the Federal University of Santa Maria about the professors perfomance, the infrastructure offered to the discipline of Statistics, it is also evalvate the degree of importance assigned by the student to these aspects. The development of the work is based on literature research and field, with qualitative approach. The data collection was conducted through a closed questionnaire, based on the Likert scale, with responses ranging into five levels of satisfaction/importance. For the data analysis, was used the tools of multivariate analysis, including cluster analysis (which has summarized the information in profiles of some groups formed by courses that had a similar behavior) and factor analysis (which enabled the validation of a research tool). It was used even the descriptive statistics for characterization of the courses and analysis of variance that allowed verify the difference among the answers to the questions by each group of courses. During the evaluation about the satisfaction with the work of the professor, the infrastructure and the discipline, could be observed that the issues presented the group 4, with Zootechnics, Archivist and Electrical Engineering courses, with a higher level of satisfaction. In the opposite, it has been the group 2, formed by Psychology and Odontology with the lowest levels of satisfaction. In some variables, the group 3, formed by Economics, Social Sciences, Geography, Chemical Engineering, Agriculture, Pharmacy, Medicine, Administration and Veterinary Medicine, showed up statistically equal to the group 4. For the other issues, the group 1, formed by Forestry Engineering, Civil Engineering, Physical Education and Computer Science and group 3 had an intermediary degree of satisfaction. In evaluating the importance of variables, could be noticed a good degree of importance gave to these variables by all groups of courses. The validation of the questionnaire of satisfaction suggested the elimination of two variables that had little relevance. The twenty-one other variables in the instrument were grouped into four distinct groups of variables: didactic-pedagogic capacity of the professor; organization/ responsibility presented by the professor; infrastructure offered, and discipline of Statistics, providing greater uniformity among the variables within each group.
A busca por qualidade na educação tem surgido de forma crescente durante os últimos anos. Percebe-se uma maior preocupação diante do atual quadro educacional por parte da sociedade, governo, professores e alunos. A presente pesquisa buscou avaliar a satisfação dos alunos do Departamento de Estatística da Universidade Federal de Santa Maria quanto à atuação do professor, à infra-estrutura oferecida e à disciplina Estatística. É avaliado também o grau de importância atribuído pelo aluno a estes aspectos. O desenvolvimento do trabalho constitui-se de pesquisa bibliográfica e de campo, com abordagem qualiquantitativa. A coleta dos dados foi realizada por meio de um questionário fechado, baseado na escala Likert, com respostas variando em cinco níveis de satisfação/importância. Para análise dos dados, recorreu-se às ferramentas da análise multivariada, entre elas, a análise de agrupamento (que possibilitou resumir a informação em perfis de alguns grupos formados pelos cursos que apresentaram um comportamento similar) e a análise fatorial (que possibilitou a validação do instrumento de pesquisa). Utilizou-se ainda a estatística descritiva para caracterização dos cursos e a análise de variância que possibilitou verificar a diferença entre as respostas atribuídas às questões por cada grupo de cursos. Na etapa de avaliação da satisfação quanto ao trabalho do professor, à infra-estrutura e à disciplina, pôde-se observar que as questões apresentaram o grupo 4, composto pelo cursos de Zootecnia, Arquivologia e Engenharia Elétrica, com um nível mais elevado de satisfação. No oposto, tem-se o grupo 2, formado pelos cursos de Psicologia e Odontologia com os menores graus de satisfação. Em algumas variáveis, o grupo 3, formado pelos cursos de Economia, Ciências Sociais, Geografia, Engenharia Química, Agronomia, Farmácia, Medicina, Administração e Medicina Veterinária, mostrou-se estatisticamente igual ao grupo 4. Para as demais questões, o grupo 1, formado pelos cursos de Engenharia Florestal, Engenharia Civil, Educação Física e Ciência da Computação e o grupo 3 apresentaram-se em um grau intermediário de satisfação. Na avaliação da importância das variáveis, pôde-se notar um bom grau de importância atribuído a tais variáveis por todos os grupos de cursos. A validação do questionário de satisfação sugeriu a eliminação de duas variáveis que apresentaram pouca relevância. As vinte e uma variáveis restantes no instrumento ficaram agrupadas em quatro grupos distintos de variáveis: Capacidade didático-pedagógica do professor; organização/responsabilidade apresentada pelo professor; infraestrutura oferecida; e, disciplina de Estatística, proporcionando maior homogeneidade entre as variáveis dentro de cada grupo.

APA, Harvard, Vancouver, ISO, and other styles

24

Zelelew, Mulugeta. "Improving Runoff Estimation at Ungauged Catchments." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for vann- og miljøteknikk, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-19675.

Full text

Abstract:

Water infrastructures have been implemented to support the vital activities of human society. The infrastructure developments at the same time have interrupted the natural catchment response characteristics, challenging society to implement effective water resources planning and management strategies. The Telemark area in southern Norway has seen a large number of water infrastructure developments, particularly hydropower, over more than a century. Recent developments in decision support tools for flood control and reservoir operation has raised the need to compute inflows from local catchments, most of which are regulated or have no observed data. This has contributed for the motivation of this PhD thesis work, with an aim of improving runoff estimation at ungauged catchments, and the research results are presented in four manuscript scientific papers. The inverse distance weighting, inverse distance squared weighting, ordinary kriging, universal kriging and kriging with external drift were applied to analyse precipitation variability and estimate daily precipitation in the study area. The geostatistical based univariate and multivariate map-correlation concepts were applied to analyse and physically understand regional hydrological response patterns. The Sobol variance based sensitivity analysis (VBSA) method was used to investigate the HBV hydrological model parameterization significances on the model response variations and evaluate the model’s reliability as a prediction tool. The HBV hydrological model space transferability into ungauged catchments was also studied. The analyses results showed that the inverse distance weighting variants are the preferred spatial data interpolation methods in areas where relatively dense precipitation station network can be found. In mountainous areas and in areas where the precipitation station network is relatively sparse, the kriging variants are the preferred methods. The regional hydrological response correlation analyses suggested that geographic proximity alone cannot explain the entire hydrological response correlations in the study area. Besides, when the multivariate map-correlation analysis was applied, two distinct regional hydrological response patterns - the radial and elliptical-types were identified. The presence of these hydrological response patterns influenced the location of the best-correlated reference streamgauges to the ungauged catchments. As a result, the nearest streamgauge was found the best-correlated in areas where the radial-type hydrological response pattern is the dominant. In area where the elliptical-type hydrological response pattern is the dominant, the nearest reference streamgauge was not necessarily the best-correlated. The VBSA verified that varying up to a minimum of four to six influential HBV model parameters can sufficiently simulate the catchments' responses characteristics when emphasis is given to fit the high flows. Varying up to a minimum of six influential model parameters is necessary to sufficiently simulate the catchments’ responses and maintain the model performance when emphasis is given to fit the low flows. However, varying more than nine out of the fifteen HBV model parameters will not make any significant change on the model performance. The hydrological model space transfer study indicated that estimation of representative runoff at ungauged catchments cannot be guaranteed by transferring model parameter sets from a single donor catchment. On the other hand, applying the ensemble based model space transferring approach and utilizing model parameter sets from multiple donor catchments improved the model performance at the ungauged catchments. The result also suggested that high model performance can be achieved by integrating model parameter sets from two to six donor catchments. Objectively minimizing the HBV model parametric dimensionality and only sampling the sensitive model parameters, maintained the model performance and limited the model prediction uncertainty.

APA, Harvard, Vancouver, ISO, and other styles

25

Goneos-Malka, Amaleya. "Marketing to young adults in the context of a postmodern society." Thesis, University of Pretoria, 2011. http://hdl.handle.net/2263/30427.

Full text

Abstract:

In today’s society media is ubiquitous. Through its pervasiveness it plays an inextricable role in society, impacting on culture, economy, politics, education and communication. In a postmodern society technological advances have had a profound impact on the development of media, most notably digital media. The intention of this study was to establish whether, in the context of an assumed postmodern culture, young South African adults display behaviour that manifest the tenets of postmodernism in their reactions to contemporary marketing and/or marketing communication, as apparent through their attitudes towards retail shopping and brands, together with their attitudes towards and use of digital media. In this instance digital media is limited to social media and media accessible on mobile phones. The unique properties and interactive capabilities of digital media have altered the dynamics of communication and have given rise to new applications that were not previously possible. This poses challenges for organisations in terms of marketing communication practices with one of the problem areas being that marketers do not know:

Whether young South African adults (Generation Y) exhibit postmodern behaviour, in the context of today’s postmodern culture.
How young South African adults (Generation Y) use digital media?
How to leverage the unique properties of digital media in marketing communication efforts directed towards young South African adults (Generation Y)?

The main purpose of this research was to reflect on the applicability of modern marketing and/or marketing communication theories, in their current state, in the context of a postmodern society, with specific emphasis on the use of digital media. The secondary purpose of the research was to investigate the affect of postmodern variables on Generation Y and the perspective of this population towards digital media and its role in marketing communication. The study aimed to contribute to the theoretical body of knowledge as follows:

To question the application of modern marketing and/or marketing communication theories in postmodern society. In so doing, it suggested that in any given era marketing theories should be representative of the target society, therefore inferring the need to adjust existing theories and their application or formulate new ones that are representative of the specific era.
To empirically determine whether Generation Y are exhibiting characteristics indicative of postmodern society.

Furthermore, the study added value from a practitioner perspective by contributing to new knowledge in the study of Generation Y and digital media. It is anticipated that an improved understanding of Generation Y’s attitudes towards marketing and digital media will serve to improve knowledge of how Generation Y will react in the future as they mature and potentially provide an indication of forthcoming generations’ attitudes towards marketing. Nine research objectives emanating from the research problem were empirically tested through a cross-sectional quantitative exploratory descriptive survey research design. Items in the survey were developed on the basis of observable postmodern characteristics presented in the literature and in consultation with a panel of experts. The survey was distributed by email, which provided a web-based link to access the survey, to the sampling frame; a database comprising of 2,265 students, between the ages of 18-34, enrolled full-time with the department of Marketing and Communication Management (University of Pretoria) during 2011. Convenience sampling was used until a sufficient quantity of fully completed surveys had been collected; 333 usable questionnaires were obtained. The collected data received statistical treatment primarily through the application of exploratory factor analysis and multivariate analysis of co-variance. The theoretical synthesis showed that characteristics of postmodernism are evident in society and affect marketing and/or marketing communication activities. The results of the empirical phase of the investigation demonstrated that respondents show postmodernism traits in their behaviour towards digital media and their reactions towards brands and marketing and/or marketing communication. The most dominant postmodern characteristics displayed by respondents were hyperreality, de-differentiation and fragmentation. Several factors were found to be statistically significant, which may be related to socio-economic conditions, behavioural patterns, and digital infrastructure. These were: ethnicity, cell phone usage, frequency of social media usage, cell phone plan, average monthly Internet expenditure for cell phones, use of Internet bundles on cell phones, and the device used most often to access the Internet. Social media use was identified as an important behavioural outcome by respondents, and the most significant influencing factors related to the dependence that respondents placed on their cell phones and the need to fulfil certain activities only available in the social media space. Finally a conceptual framework was proposed, which integrated theoretical and empirical findings. This framework suggested a broadening of certain roles within marketing and/or marketing communication, namely: consumers transforming to collaborators; communication transforming to interaction; and value exchange transforming to value-in-use. It is anticipated that this study has added to the theoretical level of knowledge by indicating the need to readdress principles and theories of marketing and/or marketing communication in the context of a postmodern society and in particular the use of digital media. An outcome of the study was the proposition of a conceptual framework, which addressed a number of aspects in the transformation from modern to postmodern marketing. Furthermore, at the practitioner level the study has broadened understanding of Generation Y’s behaviour towards digital media in the marketing and/or marketing communication context. Managerial recommendations were expressed on the basis of the theoretical and empirical findings.
Thesis (PhD)--University of Pretoria, 2011.
Marketing Management
PhD
Unrestricted

APA, Harvard, Vancouver, ISO, and other styles

26

Goneos-Malka, Amaleya Catherina. "Marketing to young adults in the context of a postmodern society." Thesis, University of Pretoria, 2002. http://hdl.handle.net/2263/30427.

Full text

Abstract:

In today’s society media is ubiquitous. Through its pervasiveness it plays an inextricable role in society, impacting on culture, economy, politics, education and communication. In a postmodern society technological advances have had a profound impact on the development of media, most notably digital media. The intention of this study was to establish whether, in the context of an assumed postmodern culture, young South African adults display behaviour that manifest the tenets of postmodernism in their reactions to contemporary marketing and/or marketing communication, as apparent through their attitudes towards retail shopping and brands, together with their attitudes towards and use of digital media. In this instance digital media is limited to social media and media accessible on mobile phones. The unique properties and interactive capabilities of digital media have altered the dynamics of communication and have given rise to new applications that were not previously possible. This poses challenges for organisations in terms of marketing communication practices with one of the problem areas being that marketers do not know:

Whether young South African adults (Generation Y) exhibit postmodern behaviour, in the context of today’s postmodern culture.
How young South African adults (Generation Y) use digital media?
How to leverage the unique properties of digital media in marketing communication efforts directed towards young South African adults (Generation Y)?

The main purpose of this research was to reflect on the applicability of modern marketing and/or marketing communication theories, in their current state, in the context of a postmodern society, with specific emphasis on the use of digital media. The secondary purpose of the research was to investigate the affect of postmodern variables on Generation Y and the perspective of this population towards digital media and its role in marketing communication. The study aimed to contribute to the theoretical body of knowledge as follows:

To question the application of modern marketing and/or marketing communication theories in postmodern society. In so doing, it suggested that in any given era marketing theories should be representative of the target society, therefore inferring the need to adjust existing theories and their application or formulate new ones that are representative of the specific era.
To empirically determine whether Generation Y are exhibiting characteristics indicative of postmodern society.

Furthermore, the study added value from a practitioner perspective by contributing to new knowledge in the study of Generation Y and digital media. It is anticipated that an improved understanding of Generation Y’s attitudes towards marketing and digital media will serve to improve knowledge of how Generation Y will react in the future as they mature and potentially provide an indication of forthcoming generations’ attitudes towards marketing. Nine research objectives emanating from the research problem were empirically tested through a cross-sectional quantitative exploratory descriptive survey research design. Items in the survey were developed on the basis of observable postmodern characteristics presented in the literature and in consultation with a panel of experts. The survey was distributed by email, which provided a web-based link to access the survey, to the sampling frame; a database comprising of 2,265 students, between the ages of 18-34, enrolled full-time with the department of Marketing and Communication Management (University of Pretoria) during 2011. Convenience sampling was used until a sufficient quantity of fully completed surveys had been collected; 333 usable questionnaires were obtained. The collected data received statistical treatment primarily through the application of exploratory factor analysis and multivariate analysis of co-variance. The theoretical synthesis showed that characteristics of postmodernism are evident in society and affect marketing and/or marketing communication activities. The results of the empirical phase of the investigation demonstrated that respondents show postmodernism traits in their behaviour towards digital media and their reactions towards brands and marketing and/or marketing communication. The most dominant postmodern characteristics displayed by respondents were hyperreality, de-differentiation and fragmentation. Several factors were found to be statistically significant, which may be related to socio-economic conditions, behavioural patterns, and digital infrastructure. These were: ethnicity, cell phone usage, frequency of social media usage, cell phone plan, average monthly Internet expenditure for cell phones, use of Internet bundles on cell phones, and the device used most often to access the Internet. Social media use was identified as an important behavioural outcome by respondents, and the most significant influencing factors related to the dependence that respondents placed on their cell phones and the need to fulfil certain activities only available in the social media space. Finally a conceptual framework was proposed, which integrated theoretical and empirical findings. This framework suggested a broadening of certain roles within marketing and/or marketing communication, namely: consumers transforming to collaborators; communication transforming to interaction; and value exchange transforming to value-in-use. It is anticipated that this study has added to the theoretical level of knowledge by indicating the need to readdress principles and theories of marketing and/or marketing communication in the context of a postmodern society and in particular the use of digital media. An outcome of the study was the proposition of a conceptual framework, which addressed a number of aspects in the transformation from modern to postmodern marketing. Furthermore, at the practitioner level the study has broadened understanding of Generation Y’s behaviour towards digital media in the marketing and/or marketing communication context. Managerial recommendations were expressed on the basis of the theoretical and empirical findings.
Thesis (PhD)--University of Pretoria, 2011.
Marketing Management
PhD
Unrestricted

APA, Harvard, Vancouver, ISO, and other styles

27

NAKMAI, SIWAT. "'Correlation and portfolio analysis of financial contagion and capital flight'." Doctoral thesis, Università Cattolica del Sacro Cuore, 2018. http://hdl.handle.net/10280/79341.

Full text

Abstract:

This dissertation mainly studies correlation and then portfolio analysis of financial contagion and capital flight, focusing on currency co-movements around the political uncertainty due to the Brexit referendum on 26 June 2016. The correlation, mean, and covariance computations in the analysis are both time-unconditional and time-conditional, and the generalized autoregressive conditional heteroskedasticity (GARCH) and exponentially weighted moving average (EWMA) methods are applied. The correlation analysis in this dissertation (Chapter 1) extends the previous literature on contagion testing based on a single global factor model, bivariate correlation analysis, and heteroskedasticity bias correction. Chapter 1 proposes an alternatively extended framework, assuming that intensification of financial correlations in a state of distress could coincide with rising global-factor-loading variability, provides simple tests to verify the assumptions of the literature and of the extended framework, and considers capital flight other than merely financial contagion. The outcomes show that, compared to the literature, the extended framework can be deemed more verified to the Brexit case. Empirically, with the UK being the shock-originating economy and the sterling value plummeting on the US dollar, there exist contagions to some other major currencies as well as a flight to quality, particularly to the yen, probably suggesting diversification benefits. When the correlation coefficients are time-conditional, or depend more on more recent data, the evidence shows fewer contagions and flights since the political uncertainty in question disappeared gradually over time. After relevant interest rates were partialled out, some previous statistical contagion and flight occurrences became less significant or even insignificant, possibly due to the significant impacts of the interest rates on the corresponding currency correlations. The portfolio analysis in this dissertation (Chapter 2) examines financial contagion and capital flight implied by portfolio reallocations through mean-variance portfolio analysis, and builds on the correlation analysis in Chapter 1. In the correlation analysis, correlations are bivariate, whereas in the portfolio analysis they are multivariate and the risk-return tradeoff is also vitally involved. Portfolio risk minimization and reward-to-risk maximization are the two analytical cases of portfolio optimality taken into consideration. Robust portfolio optimizations, using shrinkage estimations and newly proposed risk-based weight constraints, are also applied. The evidence demonstrates that the portfolio analysis outcomes regarding currency contagions and flights, implying diversification benefits, vary and are noticeably dissimilar from the correlation analysis outcomes of Chapter 1. Subsequently, it could be inferred that the diversification benefits deduced from the portfolio and correlation analyses differ owing to the dominance, during market uncertainty, of the behaviors of the means and (co)variances of all the shock-originating and shock-receiving returns, over the behaviors of just bivariate correlations between the shock-originating and shock-receiving returns. Moreover, corrections of the heteroskedasticity bias inherent in the shock-originating returns, overall, do not have an effect on currency portfolio rebalancing. Additionally, hedging demands could be implied from detected structural portfolio reallocations, probably as a result of variance-covariance shocks rising from Brexit.
This dissertation mainly studies correlation and then portfolio analysis of financial contagion and capital flight, focusing on currency co-movements around the political uncertainty due to the Brexit referendum on 26 June 2016. The correlation, mean, and covariance computations in the analysis are both time-unconditional and time-conditional, and the generalized autoregressive conditional heteroskedasticity (GARCH) and exponentially weighted moving average (EWMA) methods are applied. The correlation analysis in this dissertation (Chapter 1) extends the previous literature on contagion testing based on a single global factor model, bivariate correlation analysis, and heteroskedasticity bias correction. Chapter 1 proposes an alternatively extended framework, assuming that intensification of financial correlations in a state of distress could coincide with rising global-factor-loading variability, provides simple tests to verify the assumptions of the literature and of the extended framework, and considers capital flight other than merely financial contagion. The outcomes show that, compared to the literature, the extended framework can be deemed more verified to the Brexit case. Empirically, with the UK being the shock-originating economy and the sterling value plummeting on the US dollar, there exist contagions to some other major currencies as well as a flight to quality, particularly to the yen, probably suggesting diversification benefits. When the correlation coefficients are time-conditional, or depend more on more recent data, the evidence shows fewer contagions and flights since the political uncertainty in question disappeared gradually over time. After relevant interest rates were partialled out, some previous statistical contagion and flight occurrences became less significant or even insignificant, possibly due to the significant impacts of the interest rates on the corresponding currency correlations. The portfolio analysis in this dissertation (Chapter 2) examines financial contagion and capital flight implied by portfolio reallocations through mean-variance portfolio analysis, and builds on the correlation analysis in Chapter 1. In the correlation analysis, correlations are bivariate, whereas in the portfolio analysis they are multivariate and the risk-return tradeoff is also vitally involved. Portfolio risk minimization and reward-to-risk maximization are the two analytical cases of portfolio optimality taken into consideration. Robust portfolio optimizations, using shrinkage estimations and newly proposed risk-based weight constraints, are also applied. The evidence demonstrates that the portfolio analysis outcomes regarding currency contagions and flights, implying diversification benefits, vary and are noticeably dissimilar from the correlation analysis outcomes of Chapter 1. Subsequently, it could be inferred that the diversification benefits deduced from the portfolio and correlation analyses differ owing to the dominance, during market uncertainty, of the behaviors of the means and (co)variances of all the shock-originating and shock-receiving returns, over the behaviors of just bivariate correlations between the shock-originating and shock-receiving returns. Moreover, corrections of the heteroskedasticity bias inherent in the shock-originating returns, overall, do not have an effect on currency portfolio rebalancing. Additionally, hedging demands could be implied from detected structural portfolio reallocations, probably as a result of variance-covariance shocks rising from Brexit.

APA, Harvard, Vancouver, ISO, and other styles

28

Garcia, Marisol Peña. "Análise dos modelos AMMI bivariados." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/11/11134/tde-11022009-080418/.

Full text

Abstract:

E comum encontrar nos ensaios experimentais a analise de dois fatores, cada um com diferente numero de níveis, eles proporcionam uma tabela de dados de dupla entrada. Geralmente a analise destes dados e feita através da analise de variância - ANOVA, cumprindo algumas pressuposições básicas do modelo, mas ha outros estudos nos quais e de grande importância a interação, como e o caso dos estudos de melhoramento genético, em que o objetivo e selecionar genótipos com ótimos desempenhos em diferentes ambientes. A pouca eficiência na analise da interação dos genótipos com os ambientes (GE) da ANOVA pode representar um problema aos melhoristas, que devem tirar proveito dessa interação para os seus estudos. Os modelos aditivos com interação multiplicativa - AMMI, traz vantagens na seleção de genótipos quando comparados com métodos convencionais, pois proporcionam uma melhor analise da interação (GE), alem de permitir combinar componentes aditivos e multiplicativos em um mesmo modelo; estes modelos tem demonstrado ser eficientes na analise quando se tem apenas uma variável resposta, mas quando há mais de uma, ainda n~ao existe um procedimento geral para realizar a analise. O presente trabalho propõe uma metodologia de analise quando se têm modelos AMMI bivariados, realizando analises individuais das variáveis respostas seguidas de uma analise de procrustes, que permite fazer comparações dos resultados obtidos nas analises individuais e finalmente uma confirmação destes resultados através da analise multivariada de variância - MANOVA. Os resultados obtidos permitem concluir que a analises AMMI e procrustes proporcionam uma boa alternativa de analise para os modelos AMMI bivariados.
Is frequently nd in the studies the two way factor analysis, each factor with dierent number of levels, they conform a two way table of data, generally the analysis of the data is made with the analysis of variance - ANOVA, satisfying some assumptions, but there are some studies in which is very important the interaction, like the case of the improvement studies, where the objetive is select genotypes with optimum performance in dierents environments. The poor eciency in the genotypes and environment interaction (GE) analysis of the ANOVA can represents a problem for the researchers, that need to take advantage of the interaction. The additive main eects and multiplicative interactions model - AMMI, give advantages in the selection of genotypes when is compare with traditional methods, because give a better interaction (GE) analysis, also permit combine additive and multiplicative components in the same model, these models have demonstrated be ecient in the analysis with just one response variable but when there is more than one there is not a clear procedure to do the analysis. This work presents a analysis methodology for the bivariate AMMI models, doing individuals analysis in the response variables follow by the procrustes, which permit compare the results of the individuals analysis, and nally a conrmation of theses results with the multivariate analysis of variance - MANOVA. From the results can be concluded that the AMMI and the procrustes analysis give a good alternative for the bivariate AMMI models analysis.

APA, Harvard, Vancouver, ISO, and other styles

29

Marí, Dell'Olmo Marc 1978. "Extensiones multivariantes del modelo "Besag, York y Mollié" : Aplicación al estudio de las desigualdades socioeconómicas en la mortalidad." Doctoral thesis, Universitat Pompeu Fabra, 2012. http://hdl.handle.net/10803/98246.

Full text

Abstract:

Esta tesis tiene dos objetivos principales. El primero es proponer métodos multivariantes para el estudio de las desigualdades socioeconómicas en la mortalidad en áreas pequeñas. El segundo es estudiar estas desigualdades en la práctica en varias ciudades españolas. En consecuencia, se han realizado cuatro estudios diferentes: dos de ellos más metodológicos y los otros dos más aplicados al estudio de las desigualdades. El primer estudio metodológico propone usar Análisis Factorial Bayesiano para el cálculo de índices de privación. Además, en este estudio se concluye que ignorar la variabilidad en la estimación del índice puede conducir a un sesgo cuando las áreas se agrupan según cuantiles del índice. En el segundo estudio se ha reformulado el modelo SANOVA de modo que es posible introducir una covariable dentro de este modelo. Asimismo, dicha reformulación permite la descomposición de la varianza de los patrones estudiados como suma de varianzas de todas las componentes del modelo. Finalmente, los estudios restantes evidencian la existencia de desigualdades socioeconómicas en la mortalidad total y en la mortalidad por las principales causas específicas en once ciudades españolas. Además, para las enfermedades isquémicas del corazón estas desigualdades parecen aumentar ligeramente en el tiempo.
This thesis has two main objectives. The first is to propose multivariate methods for the study of socioeconomic inequalities in mortality in small areas. The second is to study socioeconomic inequalities in mortality in small areas of several Spanish cities. Four different studies were conducted to attain these objectives: two of them focussed on the methodological aspects and the other two being empirical studies focussed on the study of inequalities. The first methodological study proposes the Bayesian factor analysis to calculate a deprivation index. Additionally, this study concludes that ignoring the uncertainty obtained in the estimation of the index may result in a misclassification bias when the areas are grouped according to quantiles of the index. In the second methodological study the SANOVA model has been reformulated enabling the introduction of a covariate in the model. Also, this reformulation permits the decomposition of the variance of the studied patterns into the sum of variances of all the model components. Finally, the other studies show the existence of socioeconomic inequalities in total mortality and mortality by specific causes in eleven major Spanish cities. In addition, for ischemic heart disease these inequalities appear to increase slightly over time.

APA, Harvard, Vancouver, ISO, and other styles

30

Marí, Dell'Olmo Marc. "Extensiones multivariantes del modelo "Besag, York y Mollié" : Aplicación al estudio de las desigualdades socioeconómicas en la mortalidad." Doctoral thesis, Universitat Pompeu Fabra, 2012. http://hdl.handle.net/10803/98246.

Full text

Abstract:

Esta tesis tiene dos objetivos principales. El primero es proponer métodos multivariantes para el estudio de las desigualdades socioeconómicas en la mortalidad en áreas pequeñas. El segundo es estudiar estas desigualdades en la práctica en varias ciudades españolas. En consecuencia, se han realizado cuatro estudios diferentes: dos de ellos más metodológicos y los otros dos más aplicados al estudio de las desigualdades. El primer estudio metodológico propone usar Análisis Factorial Bayesiano para el cálculo de índices de privación. Además, en este estudio se concluye que ignorar la variabilidad en la estimación del índice puede conducir a un sesgo cuando las áreas se agrupan según cuantiles del índice. En el segundo estudio se ha reformulado el modelo SANOVA de modo que es posible introducir una covariable dentro de este modelo. Asimismo, dicha reformulación permite la descomposición de la varianza de los patrones estudiados como suma de varianzas de todas las componentes del modelo. Finalmente, los estudios restantes evidencian la existencia de desigualdades socioeconómicas en la mortalidad total y en la mortalidad por las principales causas específicas en once ciudades españolas. Además, para las enfermedades isquémicas del corazón estas desigualdades parecen aumentar ligeramente en el tiempo.
This thesis has two main objectives. The first is to propose multivariate methods for the study of socioeconomic inequalities in mortality in small areas. The second is to study socioeconomic inequalities in mortality in small areas of several Spanish cities. Four different studies were conducted to attain these objectives: two of them focussed on the methodological aspects and the other two being empirical studies focussed on the study of inequalities. The first methodological study proposes the Bayesian factor analysis to calculate a deprivation index. Additionally, this study concludes that ignoring the uncertainty obtained in the estimation of the index may result in a misclassification bias when the areas are grouped according to quantiles of the index. In the second methodological study the SANOVA model has been reformulated enabling the introduction of a covariate in the model. Also, this reformulation permits the decomposition of the variance of the studied patterns into the sum of variances of all the model components. Finally, the other studies show the existence of socioeconomic inequalities in total mortality and mortality by specific causes in eleven major Spanish cities. In addition, for ischemic heart disease these inequalities appear to increase slightly over time.

APA, Harvard, Vancouver, ISO, and other styles

31

Barrera, Núñez Víctor Augusto. "Automatic diagnosis of voltage disturbances in power distribution networks." Doctoral thesis, Universitat de Girona, 2012. http://hdl.handle.net/10803/80944.

Full text

Abstract:

This thesis proposes a framework for identifying the root-cause of a voltage disturbance, as well as, its source location (upstream/downstream) from the monitoring place. The framework works with three-phase voltage and current waveforms collected in radial distribution networks without distributed generation. Real-world and synthetic waveforms are used to test it. The framework involves features that are conceived based on electrical principles, and assuming some hypothesis on the analyzed phenomena. Features considered are based on waveforms and timestamp information. Multivariate analysis of variance and rule induction algorithms are applied to assess the amount of meaningful information explained by each feature, according to the root-cause of the disturbance and its source location. The obtained classification rates show that the proposed framework could be used for automatic diagnosis of voltage disturbances collected in radial distribution networks. Furthermore, the diagnostic results can be subsequently used for supporting power network operation, maintenance and planning.
En esta tesis se propone una metodología para la identificación de la localización relativa (aguas arriba/abajo) y la causa de una perturbación eléctrica. La metodología utiliza las ondas trifásicas de tensión y de corriente registradas en redes de distribución radial sin presencia de generación distribuida. La metodología es validada utilizando perturbaciones eléctricas reales y simuladas. La metodología involucra atributos que han sido concebidos basándose en principios eléctricos e hipótesis de acuerdo a cada uno de los fenómenos eléctricos analizados. Se propusieron atributos tanto basados en la forma de onda como en la fecha de ocurrencia de la perturbación. La cantidad de información contenida y/o explicada por cada atributo es valorada mediante la aplicación del análisis multivariante de la varianza y algoritmos de extracción automática de reglas de decisión. Los resultados de clasificación muestran que la metodología propuesta puede ser utilizada para el diagnóstico automático de perturbaciones eléctricas registradas en redes de distribución radial. Los resultados de diagnóstico pueden ser utilizados para apoyar las tareas de operación, mantenimiento y planeamiento de las redes de distribución.

APA, Harvard, Vancouver, ISO, and other styles

32

Hung, Ching-Ju, and 洪靜茹. "The Effect of the Missing Data Techniques for Multivariate analysis of variance(MANOVA)." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/25377256094891151536.

Full text

Abstract:

碩士
國立臺北大學
統計學系
101
In general, the outcomes of survey will be incomplete because of the respondent's personal factors. For instance, respondents merely miss to fill out some items, or reject to fill out items regarding privacy such as sensitive political issues and personal revenue. It is a common case in many social science and mental health surveys. For the sake of the restriction on ordinary statistics software, researchers have to exclude those respondent's surveys with missing data to analysis in complete data. But sometimes there are a few hidden information in deleted data and probably the results of the survey will be distorted. For the reasons mentioned above, we have to investigate the missing data's problems to get some figures showed in missing data. It becomes the important topics of survey treatment. In this study, we use Taiwan Education Panel Survey's questionnaire of students and their parents in 2001 for objects, and aim at 15 mental health questions. According to the raw missing patterns, we create five missing data sets which are one time, three, five, seven, and ten times.(The missing percentage is about 5%, 14%, 23%, 31%, 41% respectively.) We also randomly creative five groups of 30 missing data sets respectively(150 sets in total) based on different missing percentage to process the missing data. The methods of missing treatment in this study are List-wise Delete(LD), Available Case(AC), Stepwise Logistic regression(SLR), and Monte Carlo Markov Chain(MCMC). In different missing data sets, we compare the different missing treatment and baseline when both of two are used for Multivariate analysis of variance (MANOVA) on numbers of significant factors, variations of R-square, and coefficients of dependent variables. The finding shows that there is little difference as the missing percentage is low(about 5%), and the MCMC is the closest method to baseline among fours after missing treatment when the missing percentage is high(about 14%).

APA, Harvard, Vancouver, ISO, and other styles

33

Kanyama, Busanga Jerome. "A comparison of the performance of three multivariate methods in investigating the effects of province and power usage on the amounts of five power modes in South Africa." Diss., 2011. http://hdl.handle.net/10500/4681.

Full text

Abstract:

Researchers perform multivariate techniques MANOVA, discriminant analysis and factor analysis. The most common applications in social science are to identify and test the effects from the analysis. The use of this multivariate technique is uncommon in investigating the effects of power usage and Province in South Africa on the amounts of the five power modes. This dissertation discusses this issue, the methodology and practical problems of the three multivariate techniques. The author examines the applications of each technique in social public research and comparisons are made between the three multivariate techniques. This dissertation concludes with a discussion of both the concepts of the present multivariate techniques and the results found on the use of the three multivariate techniques in the energy household consumption. The author recommends focusing on the hypotheses of the study or typical questions surrounding of each technique to guide the researcher in choosing the appropriate analysis in the social research, as each technique has some strengths and limitations.
Statistics
M. Sc. (Statistics)

APA, Harvard, Vancouver, ISO, and other styles

34

Kanyama, Busanga Jerome. "A comparison of the performance of three multivariate methods in investigating the effects of province and power usage on the amount of five power modes in South Africa." Diss., 2011. http://hdl.handle.net/10500/4681.

Full text

Abstract:

Researchers perform multivariate techniques MANOVA, discriminant analysis and factor analysis. The most common applications in social science are to identify and test the effects from the analysis. The use of this multivariate technique is uncommon in investigating the effects of power usage and Province in South Africa on the amounts of the five power modes. This dissertation discusses this issue, the methodology and practical problems of the three multivariate techniques. The author examines the applications of each technique in social public research and comparisons are made between the three multivariate techniques. This dissertation concludes with a discussion of both the concepts of the present multivariate techniques and the results found on the use of the three multivariate techniques in the energy household consumption. The author recommends focusing on the hypotheses of the study or typical questions surrounding of each technique to guide the researcher in choosing the appropriate analysis in the social research, as each technique has some strengths and limitations.
Statistics
M. Sc. (Statistics)

APA, Harvard, Vancouver, ISO, and other styles

35

"Decision-theoretic estimation of parameter matrices in manova and canonical correlations." Chinese University of Hong Kong, 1995. http://library.cuhk.edu.hk/record=b5888532.

Full text

Abstract:

by Lo Tai-yan, Milton.
Thesis (M.Phil.)--Chinese University of Hong Kong, 1995.
Includes bibliographical references (leaves 112-114).
Chapter 1 --- Preliminaries --- p.1
Chapter 1.1 --- Introduction --- p.1
Chapter 1.1.1 --- The Noncentral Multivariate F distribution --- p.2
Chapter 1.1.2 --- The Central Problems and the Approach --- p.4
Chapter 1.2 --- Concepts and Terminology --- p.7
Chapter 1.3 --- Choice of Estimates --- p.10
Chapter 1.4 --- Related Work --- p.11
Chapter 2 --- Estimation of the noncentrality parameter of a Noncentral Mul- tivariate F distribution --- p.19
Chapter 2.1 --- Unbiased and Linear Estimators --- p.19
Chapter 2.1.1 --- The unbiased estimate --- p.20
Chapter 2.1.2 --- The Class of Linear Estimates --- p.24
Chapter 2.2 --- Optimal Linear Estimate --- p.32
Chapter 2.3 --- Nonlinear Estimate --- p.34
Chapter 2.4 --- Monte Carlo Simulation Study --- p.41
Chapter 2.5 --- Evaluation and Further Investigation --- p.42
Chapter 3 --- Estimation of Canonical Correlation Coefficients --- p.73
Chapter 3.1 --- Preliminary --- p.73
Chapter 3.2 --- The Estimation Problem --- p.76
Chapter 3.3 --- Orthogonally Invariant Estimates --- p.77
Chapter 3.3.1 --- The Unbiased Estimate --- p.78
Chapter 3.3.2 --- The Class of Linear Estimates --- p.78
Chapter 3.3.3 --- The Class of Nonlinear Estimates --- p.80
Chapter 3.4 --- Monte Carlo Simulation Study --- p.87
Chapter 3.5 --- Evaluation and Further Investigation --- p.89
Chapter A --- p.104
Chapter A.1 --- Lemma 3.2 --- p.104
Chapter A.2 --- Theorem 3.3 Leung(1992) --- p.105
Chapter A.3 --- The Noncentral F Identity --- p.106
Chapter B --- Bibliography --- p.111

APA, Harvard, Vancouver, ISO, and other styles

36

Tsai, Chung-Ting, and 蔡忠廷. "Analysis of Variance and Hypothesis Testing for Multivariate Local Linear Regression Models." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/jd639e.

Full text

Abstract:

碩士
國立清華大學
統計學研究所
105
In linear models, it is common to test the difference between two nested models by measuring the difference of their error sums of squares and performing an F-test. Huang and Chen (2008) [7] have extended the structure of this F-test to local polynomial regression (LPR) models (see Fan and Gijbels, 1996 [3]), constructed local and global ANOVA decompositions for LPR models, and defined an F-statistic to test whether a model function fitted by LPR is significant. This thesis extends this F-test to multivariate local linear regression (MLLR) models (see Ruppert and Wand, 1994 [17]) by mimicking a similar framework proposed by Huang and Chen (2008) [7]. We establish local and global ANOVA decompositions for MLLR models, and define two F-statistics corresponding to the following two hypotheses: (i) whether a model function fitted by MLLR is significant, and (ii) whether a model function fitted by MLLR with covariates X_2,..., X_d is more appropriate than a model function fitted by MLLR with covariates X_1,..., X_d. In the bivariate case (d = 2), the type I error and power for these two F-tests are investigated by simulations under different settings of sample sizes, correlations of covariates, values of bandwidth, and signals of rejection, while practical issues of implementing these two F-tests are also discussed, including normalization for the product kernel function. At last, these two F-tests are applied to the analysis of Boston house-price data.

APA, Harvard, Vancouver, ISO, and other styles

37

Lytkin, Nikita I. "Variance-based clustering methods and higher order data transformations and their applications." 2009. http://hdl.rutgers.edu/1782.2/rucore10001600001.ETD.000051869.

Full text

APA, Harvard, Vancouver, ISO, and other styles

38

Chen, Ying-Jen, and 陳暎仁. "Determining the contributors of variance shifts in a multivariate process using flexible discriminant analysis." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/61257004618381691847.

Full text

Abstract:

碩士
輔仁大學
應用統計學研究所
97
Due to the technology progress rapidly, the technique that can monitor multiple quality characteristics simultaneously becomes more important. Multivariate control charts are designed to detect the variation in multivariate processes, but they can not indicate which monitored quality characteristic or which subset of them is the source. It is a problem in practice. Most literatures have focused on the cases of mean shifts, but only a few studies have discussed the cases of variance shifts. This study proposes a flexible discriminant analysis (FDA) approach to determine the contributors of variance shifts when a multivariate control chart’s signal is triggered. Simulation results show that the proposed approach outperforms other traditional classification techniques, such as Fisher’s linear discriminant analysis, artificial neural network (ANN) and support vector machine (SVM). The spending time of the proposed approach is also less than ANN and SVMs’.

APA, Harvard, Vancouver, ISO, and other styles

39

Géczy, Christopher C. "Some generalized tests of mean-variance efficiency and multifactor model performance /." 1999. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:9943066.

Full text

APA, Harvard, Vancouver, ISO, and other styles

40

Cen-ZhuHuang and 黃岑筑. "Using Multivariate Analysis of Variance to Determine Deletion Position under Dependent Gene Reads Count Data." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/734z2b.

Full text

APA, Harvard, Vancouver, ISO, and other styles

41

Kim, Soyoung. "Bias and precision of eight multivariate measures of association for a fixed-effects analysis of variance model." 2003. http://purl.galileo.usg.edu/uga%5Fetd/kim%5Fsoyoung%5F200312%5Fma.

Full text

APA, Harvard, Vancouver, ISO, and other styles

42

Santos, Juan Carlos. "The implementation of phylogenetic structural equation modeling for biological data from variance-covariance matrices, phylogenies, and comparative analyses." Thesis, 2009. http://hdl.handle.net/2152/ETD-UT-2009-12-459.

Full text

Abstract:

One statistical approach with a long history in the social sciences is a multivariate method called Structural Equation Modeling (SEM). The development of SEM followed the evolution of factor and path analyses, multiple regression analysis and MACOVA. One of the key innovations of factor analysis and SEM is that they group a set of multivariate statistical approaches that condense variability among a set of variables in fewer latent (unobserved) factors. Most biological systems are multivariate, which are not easily dissected into their component parts. However, most biologists use only univariate statistical methods, which have definitive limitations in accounting for more than a few variables simultaneously. Therefore, the implementation of methodologies like SEM into biological research is necessary. However, SEM cannot be applied directly to most biological datasets or generalized across species because of the hierarchical pattern of evolutionary history (i.e., phylogenetic non-independence or signal). This report includes the theoretical grounds for the development of Phylogenetic SEM in preparation of the development of utilitarian algorithms. I have divided this report in six parts: (1) a brief introduction to factor analysis and SEM from historical perspective and a brief description of its utility; (2) a summary of the implications of using biological data and the underlying hierarchical structure due to shared common ancestry or phylogeny; (3) a summary of the two most common comparative methods to incorporate the phylogeny in univariate analyses (i.e., phylogenetic independent contrasts and phylogenetic generalized least squares); (4) I describe how some intermediate output from both comparative methods can be used to estimate the variance–covariance matrix that has been corrected for phylogenetic signal; (5) I describe how to perform a exploratory factor analysis, specifically principal component analysis, with the corrected variance–covariance matrix; and (6) I describe the development of the phylogenetic confirmatory factor analysis and phylogenetic SEM. I hope that this report encourages other researchers to develop adequate multivariate analysis that incorporate the evolutionary principles in its analyses.
text

APA, Harvard, Vancouver, ISO, and other styles

43

Magwene, Paul Mitaari. "Studies of phenotypic covariance with examples from turtles /." 1999. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:9943093.

Full text

APA, Harvard, Vancouver, ISO, and other styles

44

Chaka, Lyson. "Impact of unbalancedness and heteroscedasticity on classic parametric significance tests of two-way fixed-effects ANOVA tests." Diss., 2016. http://hdl.handle.net/10500/23287.

Full text

Abstract:

Classic parametric statistical tests, like the analysis of variance (ANOVA), are powerful tools used for comparing population means. These tests produce accurate results provided the data satisfies underlying assumptions such as homoscedasticity and balancedness, otherwise biased results are obtained. However, these assumptions are rarely satisfied in real-life. Alternative procedures must be explored. This thesis aims at investigating the impact of heteroscedasticity and unbalancedness on effect sizes in two-way fixed-effects ANOVA models. A real-life dataset, from which three different samples were simulated was used to investigate the changes in effect sizes under the influence of unequal variances and unbalancedness. The parametric bootstrap approach was proposed in case of unequal variances and non-normality. The results obtained indicated that heteroscedasticity significantly inflates effect sizes while unbalancedness has non-significant impact on effect sizes in two-way ANOVA models. However, the impact worsens when the data is both unbalanced and heteroscedastic.
Statistics
M. Sc. (Statistics)

APA, Harvard, Vancouver, ISO, and other styles

45

Pena, Ibarra Luis Patricio. "La relation entre le climat scolaire, le contexte scolaire et l'adoption des différents rôles lors d’une situation de violence scolaire." Thèse, 2016. http://hdl.handle.net/1866/14004.

Full text

Abstract:

Le sujet de la présente étude est la violence scolaire, phénomène complexe et polysémique qui préoccupe légitimement le monde de l’éducation depuis plus de trente ans. À partir des analyses factorielles exploratoires, analyses de variance factorielle et finalement analyses multivariées de covariance, cette recherche vise plus précisément à dégager la relation entre le climat scolaire, le contexte scolaire et les différents rôles adoptés par les élèves du niveau secondaire lors d’une situation de violence scolaire. Les données de la présente étude ont été collectées par Michel Janosz et son équipe pendant l’année 2010, dans quatre établissements éducatifs provenant d’une commission scolaire de la grande région de Montréal. L’échantillon de départ est composé de 1750 élèves qui fréquentent des classes ordinaires et spéciales du premier et deuxième cycle du secondaire âgés entre 10 et 18 ans. Pour fins d’analyse, deux petites écoles ainsi que les classes spéciales ont été retirées. Il demeure donc 1551 élèves dans l’échantillon initial analysé. Les résultats des analyses permettent de constater d’une part, la relation significative existante entre les dimensions du climat scolaire et l’adoption des différents rôles lors d’une situation de violence scolaire, les climats d’appartenance et de sécurité étant les plus importants, et d’autre part d’observer des différences dans les perceptions que les élèves ont de la violence scolaire selon le niveau et selon l’école.
The present study pertains to a complex and polysemic phenomenon that has preoccupied people working in the field of education since at least thirty years, that is, school violence. Using factor analysis, analysis of variance and multivariate analysis of covariance, this research aims at exploring specifically the relationship between school climate, school context and the various roles adopted by students at the high school level when they face a situation in which school violence in present. Data for this study were collected by Michel Janosz and his team in 2010, within four schools, all in the same school board of the Montreal region. The original sample comprises 1750 students who attend both standard special classes, between 10 and 18 years of age. The analyses presented are based on a reduced sample where the special classes and the two small schools have been withdrawn. Therefore, the answers from 1551 student s are used. The results show that first, there is a significant relationship between the various dimensions of school climate and the different roles adopted by students facing a situation in which violence is present, perceptions of belonging and of security being the most important. Second, all things being equal, there are significant difference between schools, and school levels.

APA, Harvard, Vancouver, ISO, and other styles

46

Carvalho, Francisco Ricardo Duarte de. "Análise fatorial." Master's thesis, 2013. http://hdl.handle.net/10316/33696.

Full text

Abstract:

Dissertação de Mestrado em Matemática apresentada à Faculdade de Ciências e Tecnologia da Universidade de Coimbra
A análise fatorial é um método estatístico multivariado cujo objetivo é agrupar p variáveis aleatórias, X1, . . . ,Xp, em grupos formados por variáveis fortemente correlacionadas. Tais grupos constituem os chamados fatores ou variáveis latentes. Os fatores são variáveis aleatórias não observáveis, preferencialmente em número inferior ao das variáveis originais. Neste trabalho, considera-se o modelo fatorial ortogonal, no qual os fatores são ortogonais dois a dois. No modelo fatorial, cada variável original é escrita como combinação linear dos fatores comuns adicionada de um fator específico. Para estimar os coeficientes dos fatores comuns, denominados pesos fatoriais, são abordados dois métodos, nomeadamente, o método das componentes principais e o método da máxima verosimilhança, sendo o primeiro desenvolvido com mais pormenor. Neste sentido, começa-se por definir e obter as componentes principais de uma população. O procedimento correspondente envolve os valores próprios e os vetores próprios da matriz de correlações ou da matriz de variâncias-covariâncias das variáveis X1, . . . ,Xp. Seguidamente, obtêmse as componentes principais amostrais e apresentam-se estimadores para os parâmetros envolvidos, em particular, estimadores de máxima verosimilhança no caso em que o vetor aleatório [X1 . . .Xp]T tem distribuição normal multivariada. Referem-se vários critérios para escolher o número m de fatores, m < p, e, considerando os fatores como eixos ortogonais, aborda-se a rotação ortogonal dos mesmos, com vista a facilitar a sua interpretação. Apesar dos fatores comuns serem variáveis não observáveis, é possível estimar o valor de cada fator (score) para cada indivíduo da amostra. Neste trabalho referem-se dois métodos para atingir esse objetivo: o método dos mínimos quadrados ponderados e o método da regressão. Finalmente, apresenta-se um exemplo de aplicação da análise fatorial, desenvolvido com recurso ao software SPSS.
Factor analysis is a multivariate statistical method with the objective of grouping p random variables X1, . . . ,Xp in groups formed by strongly correlated variables. These groups are called factors or latent variables. The factors are unobservable random variables, preferably in smallest number that the original variables. In this work, is considered the orthogonal factorial model, in which the factors are orthogonal two linear combination of the common factors and added to a specific factor. To estimate the coefficients of common factors, called loadings, we will see two methods, namely, the method of principal components and the method of maximum likelihood, the first being developed in more detail. We starts by define and obtain principal components of a population. The corresponding procedure involves the eigenvalues and eigenvectors of the correlation matrix or the variance-covariance matrix of the variables X1, . . . ,Xp. Then, we obtain the principal components of sample and we present the estimators for involved parameters, in particular, maximum likelihood estimators in case that the random vector [X1 . . .Xp]T has multivariate normal distribution. We refer several criteria to choose the number m of factors, m < p, and, considering the factors as orthogonal axes, we study the orthogonal rotation, to facilitate their interpretation. Although the common factors are unobservable variables, we can estimate the value of each factor (score) for each element of sample. In this work we refer two methods to achieve this objective: the method of weighted least squares and the regression method. Finally, we present an example of application of factor analysis, developed using the SPSS software.

APA, Harvard, Vancouver, ISO, and other styles

47

Wilson, Adam Benjamin. "A Psychometric Evaluation of Script Concordance Tests for Measuring Clinical Reasoning." Thesis, 2014. http://hdl.handle.net/1805/3877.

Full text

Abstract:

Indiana University-Purdue University Indianapolis (IUPUI)
Purpose: Script concordance tests (SCTs) are assessments purported to measure clinical data interpretation. The aims of this research were to (1) test the psychometric properties of SCT items, (2) directly examine the construct validity of SCTs, and (3) explore the concurrent validity of six SCT scoring methods while also considering validity at the item difficulty and item type levels. Methods: SCT scores from a problem solving SCT (SCT-PS; n=522) and emergency medicine SCT (SCT-EM; n=1040) were used to investigate the aims of this research. An item analysis was conducted to optimize the SCT datasets, to categorize items into levels of difficulty and type, and to test for gender biases. A confirmatory factor analysis tested whether SCT scores conformed to a theorized unidimensional factor structure. Exploratory factor analyses examined the effects of six SCT scoring methods on construct validity. The concurrent validity of each scoring method was also tested via a one-way multivariate analysis of variance (MANOVA) and Pearson’s product moment correlations. Repeated measures analysis of variance (ANOVA) and one-way ANOVA tested the discriminatory power of the SCTs according to item difficulty and type. Results: Item analysis identified no gender biases. A combination of moderate model-fit indices and poor factor loadings from the confirmatory factor analysis suggested that the SCTs under investigation did not conform to a unidimensional factor structure. Exploratory factor analyses of six different scoring methods repeatedly revealed weak factor loadings, and extracted factors consistently explained only a small portion of the total variance. Results of the concurrent validity study showed that all six scoring methods discriminated between medical training levels in spite of lower reliability coefficients on 3-point scoring methods. In addition, examinees as MS4s significantly (p<0.001) outperformed their MS2 SCT scores in all difficulty categories. Cross-sectional analysis of SCT-EM data reported significant differences (p<0.001) between experienced EM physicians, EM residents, and MS4s at each level of difficulty. When considering item type, diagnostic and therapeutic items differentiated between all three training levels, while investigational items could not readily distinguish between MS4s and EM residents. Conclusions: The results of this research contest the assertion that SCTs measure a single common construct. These findings raise questions about the latent constructs measured by SCTs and challenge the overall utility of SCT scores. The outcomes of the concurrent validity study provide evidence that multiple scoring methods reasonably differentiate between medical training levels. Concurrent validity was also observed when considering item difficulty and item type.

APA, Harvard, Vancouver, ISO, and other styles

48

Pryse, Yvette M. "Using Evidence Based Practice: The Relationship Between Work Environment, Nursing Leadership and Nurses at the Bedside." Thesis, 2013. http://hdl.handle.net/1805/3220.

Full text

Abstract:

Indiana University-Purdue University Indianapolis (IUPUI)
Evidence based practice (EBP) is essential to the practice of nursing for purposes of promoting optimal patient outcomes. Research suggests that the implementation of EBP by staff nurses is problematic and influenced by beliefs, nursing leadership and the work environment. The purpose of this descriptive study was to examine variables that describe the relationship among beliefs about EBP, the work environment and nursing leadership on the EBP implementation activities of the staff nurse. The variables of interest were 1) individual staff nurse characteristics, 2) beliefs about EBP, 3) the EBP work environment and 4) nursing leadership for EBP. A descriptive, quantitative method was used. A sample of 422 Registered Nurses from two urban hospitals (one Magnet and one non-Magnet) completed an online 58 item survey that included questions related to individual belief’s about EBP, the EBP work environment and nursing leadership for EBP as well as EBP implementation activities. Education, tenure and Magnet status were not significantly related to EBP implementation activities in either the univariate or multivariate analysis. EBP beliefs had a significantly positive relationship with EBP implementation activities in both the univariate and multivariate analyses. Work environment and nursing leadership support for EBP had significant positive relationships with self-reported implementation activities in only the univariate analysis. The most surprising finding was that there were no differences between Magnet and non-Magnet work environments for EBP implementation scores, yet the Magnet hospitals reported higher means on the EBP Beliefs Scale than the non-Magnet hospital. The results of this have implications for identifying and testing strategies to influence EBP implementation activities through development of nursing leadership skills for EBP and creating a more EBP friendly work environment.

APA, Harvard, Vancouver, ISO, and other styles

Dissertations / Theses on the topic 'Multivariate analysis of variance MANOVA'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles