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Calibration of trip distribution by generalised linear modelsShrewsbury, John Stephen January 2012 (has links)
Generalised linear models (GLMs) provide a flexible and sound basis for calibrating gravity models for trip distribution, for a wide range of deterrence functions (from steps to splines), with K factors and geographic segmentation. The Tanner function fitted Wellington Transport Strategy Model data as well as more complex functions and was insensitive to the formulation of intrazonal and external costs. Weighting from variable expansion factors and interpretation of the deviance under sparsity are addressed.
An observed trip matrix is disaggregated and fitted at the household, person and trip levels with consistent results. Hierarchical GLMs (HGLMs) are formulated to fit mixed logit models, but were unable to reproduce the coefficients of simple nested logit models.
Geospatial analysis by HGLM showed no evidence of spatial error patterns, either as random K factors or as correlations between them. Equivalence with hierarchical mode choice, duality with trip distribution, regularisation, lorelograms, and the modifiable areal unit problem are considered.
Trip distribution is calibrated from aggregate data by the MVESTM matrix estimation package, incorporating period and direction factors in the intercepts. Counts across four screenlines showed a significance similar to a thousand-household travel survey. Calibration was possible only in conjuction with trip end data. Criteria for validation against screenline counts were met, but only if allowance was made for error in the trip end data.
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Modélisation statistique de données fonctionnelles environnementales : application à l'analyse de profils océanographiques. / Statistical modeling of environmental functional data : application to the analyse of oceanographic profiles.Bayle, Severine 12 June 2014 (has links)
Afin d'étudier les processus biogéochimiques de l'Océan Austral, des balises posées sur des éléphants de mer ont permis de récolter en 2009-2010 des profils de variables océanographiques (Chlorophylle a (Chl a), température, salinité, lumière) dans une zone s'étalant du sud des îles Kerguelen jusqu'au continent Antarctique. Cette thèse se penche en particulier sur les données de Chl a, car celle-ci est contenue dans les organismes photosynthétiques qui jouent un rôle essentiel de pompe à carbone. Mais les profils verticaux de Chl a, récoltés peu fréquemment, ne permettent pas d'obtenir une cartographie de cette variable dans cette zone de l'océan. Cependant, nous disposons de profils de lumière, échantillonnés plus souvent. L'objectif était alors de développer une méthodologie permettant de reconstruire de manière indirecte les profils de Chl a à partir des profils de lumière, et qui prenne en compte les caractéristiques de ce type de données qui se présentent naturellement comme des données fonctionnelles. Pour cela, nous avons abordé la décomposition des profils à reconstruire ou explicatifs sur une base de splines, ainsi que les questions d'ajustement associées. Un modèle linéaire fonctionnel a été utilisé, permettant de prédire des profils de Chl a à partir des dérivées des profils de lumière. Il est montré que l'utilisation d'un tel modèle permet d'obtenir une bonne qualité de reconstruction pour accéder aux variations hautes fréquences des profils de Chl a à fine échelle. Enfin, une interpolation par krigeage fonctionnel permet de prédire la concentration en Chl a de nuit, car les mesures de lumière acquises à ce moment-là ne peuvent pas être exploitées. / To study biogeochemical processes in the Southern Ocean, tags placed on elephant seals allowed to collect during 2009-2010 oceanographic variables profiles (Chlorophyll a (Chl a), temperature, salinity, light) in an area ranging from southern Kerguelen until the Antarctic continent. This thesis focuses on Chl a data as it is contained in photosynthetic organisms and these ones play an essential role in the oceanic carbon cycle. The infrequently collected vertical Chl a profiles don't provide a mapping of this variable in this area of the ocean. However, we have light profiles sampled more often. The aim of this thesis was then to develop a methodology for reconstructing indirectly Chl a profiles from light profiles, and that takes into account characteristics of this kind of data that naturally occur as functional data. For this, we adressed the profiles decomposition to rebuild or explanations on splines basis, as well as issues related adjustment. A functional linear model was used to predict Chl a profiles from light profiles derivatives. It was shown that the use of such a model provides a good quality of reconstruction to access high frequency variations of Chl a profiles at fine scale. Finally, a functional kriging interpolation predicted the Chl a concentration during night, as light measurements acquired at that time can't be exploited. In the future, the methodology aims to be applied to any type of functional data.
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Spotřební chování / Consumer BehaviourBabáková, Andrea January 2010 (has links)
The thesis focuses on investigating and searching for differences between consumer behavior of Czech and Slovak households depending on chosen socioeconomic factors. For the purpose of this thesis source materials are taken mainly from researches realized by Czech and Slovak Statistical Office, specifically from survey sampling Household Budget Study 2009. Data are analyzed through the use of comprehensive characteristics of location, variability and box diagrams. Generalized linear models are used for modeling dependence of consumer behavior on chosen quantitative and qualitative factors. Household consumer behavior is expressed through economic index - propensity to consume - which is determined by the share of total monthly income and expenditures.
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Modelo linear parcial generalizado simétrico / Linear Model Partial Generalized SymmetricVasconcelos, Julio Cezar Souza 06 February 2017 (has links)
Neste trabalho foi proposto o modelo linear parcial generalizado simétrico, com base nos modelos lineares parciais generalizados e nos modelos lineares simétricos, em que a variável resposta segue uma distribuição que pertence à família de distribuições simétricas, considerando um preditor linear que possui uma parte paramétrica e uma não paramétrica. Algumas distribuições que pertencem a essa classe são as distribuições: Normal, t-Student, Exponencial potência, Slash e Hiperbólica, dentre outras. Uma breve revisão dos conceitos utilizados ao longo do trabalho foram apresentados, a saber: análise residual, influência local, parâmetro de suavização, spline, spline cúbico, spline cúbico natural e algoritmo backfitting, dentre outros. Além disso, é apresentada uma breve teoria dos modelos GAMLSS (modelos aditivos generalizados para posição, escala e forma). Os modelos foram ajustados utilizando o pacote gamlss disponível no software livre R. A seleção de modelos foi baseada no critério de Akaike (AIC). Finalmente, uma aplicação é apresentada com base em um conjunto de dados reais da área financeira do Chile. / In this work we propose the symmetric generalized partial linear model, based on the generalized partial linear models and symmetric linear models, that is, the response variable follows a distribution that belongs to the symmetric distribution family, considering a linear predictor that has a parametric and a non-parametric component. Some distributions that belong to this class are distributions: Normal, t-Student, Power Exponential, Slash and Hyperbolic among others. A brief review of the concepts used throughout the work was presented, namely: residual analysis, local influence, smoothing parameter, spline, cubic spline, natural cubic spline and backfitting algorithm, among others. In addition, a brief theory of GAMLSS models is presented (generalized additive models for position, scale and shape). The models were adjusted using the package gamlss available in the free R software. The model selection was based on the Akaike criterion (AIC). Finally, an application is presented based on a set of real data from Chile\'s financial area.
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Estudo dos aspectos avaliados em decisões de terceirização de tecnologia da informação. / Study of the aspects considered on information technology outsourcing decisions.Ferreira, André Machado Dias 09 December 2008 (has links)
A crescente importância do mercado de serviços terceirizados de TI no Brasil e o interesse por pesquisas nesse tema no Brasil e em nível mundial, são os principais argumentos que justificam a realização deste estudo. Este trabalho teve por objetivo entender questões que envolvem os aspectos considerados em decisões de terceirização de funções de TI em empresas brasileiras, visão ainda pouco explorada na literatura. Para que o objetivo fosse atingido, foram propostas quatro questões de pesquisa respondidas utilizando-se de uma revisão bibliográfica, simulação e dois surveys. Os resultados encontrados permitiram identificar um modelo final que facilita um melhor entendimento sobre como a decisão de terceirização é tomada em empresas brasileiras. Tal modelo engloba seis aspectos de decisão usualmente considerados pelas empresas, o inter-relacionamento entre estes aspectos e mostra fatores externos que contribuem para a definição do nível de importância de cada aspecto na decisão. Como produto secundário, a discussão dos resultados encontrados frente à literatura que trata do tema terceirização em TI validou resultados já apresentados por outros autores e, gerou a necessidade de estudos futuros ao encontrar divergências. Do ponto de vista prático, o trabalho apresenta importante contribuição, pois ajudou a estruturar o processo de decisão de terceirização de funções de TI. / The growing importance of IT service market in Brazil and the interest for researches in this area in Brazil and worldwide are the main arguments that justifies the development of this study. The objective of this work was to understand the issues that involve the aspects considered on IT outsourcing decisions in Brazilian companies, theme that is not well explored in the literature. To achieve this objective, it was proposed four research questions answered by a bibliographic revision, simulation and two surveys. The founded results allowed the identification of a final model that facilitates a better understanding about how outsourcing decision making process occurs in Brazilian companies. This model considers six decisions aspects usually considered by the companies, the inter-relationship between this aspects and shows external factors that contributes to the definition of the importance level of each of these aspects in the decision making process. As secondary product, the discussion of the founded results against the literature that covers IT outsource theme, validated the results already presented by other authors and created the need of future researches by presenting some different results. From practicing stand point, this work presents an important contribution, by helping to structure the IT outsourcing decision making process.
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Estudo de expressão gênica em citros utilizando modelos lineares / Gene expression study in citrus using linear modelsFerreira Filho, Diógenes 12 February 2010 (has links)
Neste trabalho apresenta-se uma revisão da metodologia de experimentos de microarray relativas a sua instalação e análise estatística dos dados obtidos. A seguir, aplica-se essa metodologia na análise de dados de expressão gênica em citros, gerados por um experimento de macroarray, utilizando modelos lineares de efeitos fixos considerando a inclusão ou não de diferentes efeitos e considerando ajustes de modelos para cada gene separadamente e para todos os genes simultaneamente. Os experimentos de macroarray são similares aos experimentos de microarray, porém utilizam um menor número de genes. Em geral, são utilizados devido a restrições econômicas. Devido ao fato de terem sido utilizados poucos arrays no experimento analisado neste trabalho foi utilizada uma abordagem bayesiana empírica que utiliza estimativas de variância mais estáveis e que leva em consideração a correlação entre as repetições do gene dentro do array. Também foi utilizado um método de análise não paramétrico para contornar o problema da falta de normalidade para alguns genes. Os resultados obtidos em cada um dos métodos de análise descritos foram então comparados. / This paper presents a review of the methodology of microarray experiments for its installation and statistical analysis of data obtained. Then this methodology is applied in data analysis of gene expression in citrus, generated by a macroarray experiment, using linear models with fixed effects considering the inclusion or exclusion of different effects and considering adjustments of models for each gene separately and for all genes simultaneously. The macroarray experiments are similar to the microarray experiments, but use a smaller number of genes. In general, are used due to economic restrictions. Because they have been used a few arrays in the experiment analyzed in this study it was used a empirical Bayes approach that uses estimates of variance more stable and that takes into account the correlation among replicates of the gene within array. A non parametric analysis method was also used to outline the problem of the non normality for some genes. The results obtained in each of the described methods of analysis were then compared.
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Relação entre poluição do ar e internações de adultos por doenças cardiovasculares totais em São Paulo entre 2000 e 2013Bezerra, Yuri Charllub Pereira 30 January 2017 (has links)
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Previous issue date: 2017-01-30 / This observational, ecological time series study aims to verify the relationship between adult hospitalizations for total cardiovascular diseases (CVDD) and air pollution stratified by sex in residents of the city of São Paulo from 2000 to 2013, observing their Structure of lag. Analyzes were stratified by age group and sex and included hospitalizations for Total Cardiovascular Diseases (ICD10: Chapter IX - I00-I99). The pollutant and meteorological data were provided by the Environmental Sanitation Technology Company of the State of São Paulo. The relationship between air pollutants and climatic factors in hospitalizations for Total Cardiovascular Diseases was analyzed by means of a polynomial distribution lag model for both temperature and air pollutants with a lag structure of up to 6 days after exhibition. Generalized linear models of Poisson regression were used, controlling for long-term seasonality, days of the week, and holidays. The following was calculated the increase in the number of hospitalizations for the interquartile difference of the pollutants significant in the regression model, as well as for the meteorological factors. For all hospital admissions for Total Cardiovascular Diseases, acute short-term effects were observed. The O3 was the only pollutant that did not have any relation to any of the analyzed results and NO2 had the greater effect, for an increase of interquartile 50.22 ¿g / m 3 of NO2, an increase of 13.09% (IC95 %: 4.74% - 21.45%), among the total admissions from 30 to 44 years. Stratifying the analysis by age group, a greater effect was found for hospitalizations from 45 to 60 years. Regarding gender, between the age group 30 and 44, the men stood out, and for the 45-60 age group, the women were more affected than the men. / Este estudo observacional, ecológico de series temporais tem por objetivo de verificar a relação entre internações de adultos por doenças cardiovasculares totais (DCVT) e poluição do ar estratificado por sexo, em residentes do município de São Paulo no período de 2000 a 2013, observando sua estrutura de defasagem. As analises foram estratificadas por faixa etária e sexo e incluíram internações por Doenças Cardiovasculares Totais (CID10: capítulo IX - I00-I99). Os dados de poluentes e meteorológicos foram fornecidos pela Companhia de Tecnologia de Saneamento Ambiental do Estado de São Paulo. A relação entre poluentes do ar e fatores climáticos nas internações por Doenças Cardiovasculares Totais, foram analisadas por meio de um modelo de defasagem de distribuição polinomial tanto para a temperatura como para os poluentes do ar, com uma estrutura de defasagem de até 6 dias após a exposição. Foram utilizados modelos lineares generalizados de regressão de Poisson, controlando-se para sazonalidade de longa duração, dias da semana e feriados. A seguir foi calculado o aumento no número de internações para a diferença interquartil dos poluentes significativos no modelo de regressão, bem como para os fatores meteorológicos. Para todas as admissões hospitalares por Doenças Cardiovasculares Totais, foram observados efeitos agudos de curta duração. O O3 foi o único poluente que não teve relação a nenhum dos desfechos analisados e o NO2 foi o que teve o efeito maior, para um aumento de interquartil 50,22 µg/m³ de NO2, revelou um aumento de 13,09% (IC95%: 4,74% - 21,45%), entre as internações totais de 30 a 44 anos. Estratificando a análise por faixa etária, encontrou-se um maior efeito para as internações de 45 a 60 anos. No que diz respeito ao sexo, entre a faixa etária 30 a 44, sobressaíram os homens, e para a faixa etária de 45 a 60 anos, as mulheres foram mais afetadas que os homens.
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A Comparison of Modern Longitudinal Change Models with an Examination of Alternative Error Covariance StructuresMaerten-Rivera, Jaime 22 April 2010 (has links)
The purpose of this research was to compare results from two approaches to measuring change over time. The multilevel model (MLM) and latent growth model (LGM) were imposed and the parameter estimates were compared, along with model fit. The study came out of education and used data collected from 191 teachers as part of a professional development intervention in science, which took place over four years. There were missing data as a result of teacher attrition. Teachers reported use of reform-oriented practices (ROP) was used as the outcome, and teacher-level variables were examined for their impact on initial ROP and change in ROP from baseline to one year after the intervention. Change in ROP was examined using a piecewise change model where two linear slopes were modeled. The first slope estimated the change from baseline to T1, or the initial change after the intervention while the second slope estimated the change from T1 to T3, or the secondary change. Parameter estimates obtained from MLM and LGM for a model using the error covariance structure commonly assumed in MLM (i.e., random slopes, homogeneous level-1 variance) were nearly identical. Models with various alternative covariance structures (commonly associated with the LGM framework) were examined, and results were nearly identical. Most of the model fit information was in agreement regarding the best fitting model being the model that assumed the typical MLM error covariance structure with the exception of the standardized root mean square residual (SRMR) fit index. The results from the models demonstrated that ROP increased after participating in the first year of the intervention and this level was sustained, though did not increase significantly in subsequent years. There was more variation in ROP at baseline. This information tells us that the intervention was successful in that after participating in the intervention the teachers' used ROP more frequently. The success of the intervention did not depend on any of the predictors that we assessed, and, as a group, the teachers became more similar in their use of reform-oriented practices over time.
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Testing for spatial correlation and semiparametric spatial modeling of binary outcomes with application to aberrant crypt foci in colon carcinogenesis experimentsApanasovich, Tatiyana Vladimirovna 01 November 2005 (has links)
In an experiment to understand colon carcinogenesis, all animals were exposed to a carcinogen while half the animals were also exposed to radiation. Spatially, we measured the existence of aberrant crypt foci (ACF), namely morphologically changed colonic crypts that are known to be precursors of colon cancer development. The biological question of interest is whether the locations of these ACFs are spatially correlated: if so, this indicates that damage to the colon due to carcinogens and radiation is localized. Statistically, the data take the form of binary outcomes (corresponding to the existence of an ACF) on a regular grid. We develop score??type methods based upon the Matern and conditionally autoregression (CAR) correlation models to test for the spatial correlation in such data, while allowing for nonstationarity. Because of a technical peculiarity of the score??type test, we also develop robust versions of the method. The methods are compared to a generalization of Moran??s test for continuous outcomes, and are shown via simulation to have the potential for increased power. When applied to our data, the methods indicate the existence of spatial correlation, and hence indicate localization of damage. Assuming that there are correlations in the locations of the ACF, the questions are how great are these correlations, and whether the correlation structures di?er when an animal is exposed to radiation. To understand the extent of the correlation, we cast the problem as a spatial binary regression, where binary responses arise from an underlying Gaussian latent process. We model these marginal probabilities of ACF semiparametrically, using ?xed-knot penalized regression splines and single-index models. We ?t the models using pairwise pseudolikelihood methods. Assuming that the underlying latent process is strongly mixing, known to be the case for many Gaussian processes, we prove asymptotic normality of the methods. The penalized regression splines have penalty parameters that must converge to zero asymptotically: we derive rates for these parameters that do and do not lead to an asymptotic bias, and we derive the optimal rate of convergence for them. Finally, we apply the methods to the data from our experiment.
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Novel Statistical Methods in Quantitative Genetics : Modeling Genetic Variance for Quantitative Trait Loci Mapping and Genomic EvaluationShen, Xia January 2012 (has links)
This thesis develops and evaluates statistical methods for different types of genetic analyses, including quantitative trait loci (QTL) analysis, genome-wide association study (GWAS), and genomic evaluation. The main contribution of the thesis is to provide novel insights in modeling genetic variance, especially via random effects models. In variance component QTL analysis, a full likelihood model accounting for uncertainty in the identity-by-descent (IBD) matrix was developed. It was found to be able to correctly adjust the bias in genetic variance component estimation and gain power in QTL mapping in terms of precision. Double hierarchical generalized linear models, and a non-iterative simplified version, were implemented and applied to fit data of an entire genome. These whole genome models were shown to have good performance in both QTL mapping and genomic prediction. A re-analysis of a publicly available GWAS data set identified significant loci in Arabidopsis that control phenotypic variance instead of mean, which validated the idea of variance-controlling genes. The works in the thesis are accompanied by R packages available online, including a general statistical tool for fitting random effects models (hglm), an efficient generalized ridge regression for high-dimensional data (bigRR), a double-layer mixed model for genomic data analysis (iQTL), a stochastic IBD matrix calculator (MCIBD), a computational interface for QTL mapping (qtl.outbred), and a GWAS analysis tool for mapping variance-controlling loci (vGWAS).
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