Orientador: Hildete Prisco Pinheiro / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Matemática, Estatística e Computação Científica / Made available in DSpace on 2018-08-24T02:10:38Z (GMT). No. of bitstreams: 1 Argenton_JulianaLuzPassos_M.pdf: 2087574 bytes, checksum: b6014c3478501f5128fd13ddf952e6dd (MD5) Previous issue date: 2013 / Resumo: O objetivo deste trabalho é apresentar uma metodologia de árvore de regressão para dados censurados e correlacionados. O conjunto de dados analisado foi obtido a partir de uma pesquisa realizada entre Dezembro de 2005 e Janeiro de 2006, que entrevistou 119 famílias (1712 indivíduos) que vivem no pequeno vilarejo de Baependi, no Estado de Minas Gerais. São apresentadas duas metodologias com base no modelo de riscos proporcionais, a primeira desconsidera a possível correlação existente entre os indivíduos de uma mesma família e usa a primeira iteração da estimativa da verossimilhança completa nas divisões dos nós. Na segunda metodologia apresentada, a correlação entre os indivíduos de uma mesma família é incorporada no modelo de riscos proporcionais através de uma variável de fragilidade com distribuição Gama, neste caso o valor da estatística Escore é usado para escolher a melhor divisão dos nós. O objetivo da análise é avaliar as variáveis que aumentam o risco de apresentar hipertensão, diabetes tipo II e colesterol alto, que são os três principais fatores que aumentam o risco de doenças no coração. As variáveis respostas são as idades de diagnóstico desses fatores de risco. A censura é definida de acordo com a observação da idade do indivíduo no momento do diagnóstico da doença e a idade do indivíduo no momento da pesquisa. Desta forma, uma idade de diagnóstico maior que a idade no momento da pesquisa caracteriza a censura. / Abstract: The objective of this work is to present methods of regression trees for censored and correlated data. The dataset analyzed was obtained from a survey, in which 119 families (1712 individuals) living in Baependi village, in the Brazilian state of Minas Gerais, were interviewed. Two methodologies based on the proportional hazard model are presented. The first disregards the possible correlation among the individuals of the same family, using the first step of a full likelihood estimation procedure for splitting nodes. In the second methodology, the correlation among the individuals of the same family is incorporated in the proportional hazard model through a frailty variable with Gamma distribution. In this case, the value of the Score statistic is used for choosing the best splitting node. The main purpose of the analysis is to evaluate the variables that increase the risk of hypertension, type II diabetes and high cholesterol, which are the top three main factors that increase the risk of heart conditions. The response variables are the age-of-onset of these risk factors. Censoring is defined by observing the individual's age-of-onset at the moment of diagnosis and also at the moment of the survey. This way, an age-of-onset higher than the age at the moment of the survey indicates censoring. / Mestrado / Estatistica / Mestra em Estatística

Thesis (M.Sc. (Statistics)) -- University of Limpopo, 2019 / Recurrent peritonitis is a major problem of peritoneal dialysis (PD) due to its association with technique failure in the dialysis process. The literature on peritonitis focused only on investigating major risk factors associated with the first episode of peritonitis. However, this dissertation investigates factors associated to multiple episodes of peritonitis, to a maximum of 6 episodes. The correlation of recurrent episodes of a patient is considered. The univariate counting process, stratified, gap-time and marginal hazard regression models are applied to select the significant covariates to the multivariate regression hazard models. Regression coefficient for covariates are found to be statistically significant at 5% level. The application of Akaike information criterion (AIC) and Schwarz bayesian criterion (SBC) assisted to filter out the best method which is the stratified regression hazard model. The major risk factors associated with recurrent episodes of peritonitis are examined from the selected good fitting model. In conclusion, the selected model identified two independent risk factors to be significantly associated with recurrent episodes of peritonitis: marital status and glomerularfiltrationrate. Twocategoriesofmaritalstatus, divorceandwidowerare the significant factors compared to married patients (when taking married patients as the reference category). / VLIROUC Programme

Lam Yuk Fai. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 41-43). / Abstracts in English and Chinese. / Chapter 1 --- Basic Concepts --- p.9 / Chapter 1.1 --- Survival data --- p.9 / Chapter 1.1.1 --- An example --- p.9 / Chapter 1.2 --- Some important functions --- p.11 / Chapter 1.2.1 --- Survival function --- p.12 / Chapter 1.2.2 --- Hazard function --- p.12 / Chapter 1.3 --- Cox Proportional Hazards Model --- p.13 / Chapter 1.3.1 --- A special case --- p.14 / Chapter 1.3.2 --- An example (continued) --- p.15 / Chapter 1.4 --- Extension of the Cox Proportional Hazards Model --- p.16 / Chapter 1.5 --- Bootstrap --- p.17 / Chapter 2 --- A New Method --- p.19 / Chapter 2.1 --- Introduction --- p.19 / Chapter 2.2 --- Definition of the test --- p.20 / Chapter 2.2.1 --- Our test statistic --- p.20 / Chapter 2.2.2 --- The alternative test statistic I --- p.22 / Chapter 2.2.3 --- The alternative test statistic II --- p.23 / Chapter 2.3 --- Variations of the test --- p.24 / Chapter 2.3.1 --- Restricted test --- p.24 / Chapter 2.3.2 --- Adjusting for other covariates --- p.26 / Chapter 2.4 --- Apply with bootstrap --- p.28 / Chapter 2.5 --- Examples --- p.29 / Chapter 2.5.1 --- Male mice data --- p.34 / Chapter 2.5.2 --- Stanford heart transplant data --- p.34 / Chapter 2.5.3 --- CGD data --- p.34 / Chapter 3 --- Large Sample Properties and Discussions --- p.35 / Chapter 3.1 --- Large sample properties and relationship to goodness of fit test --- p.35 / Chapter 3.1.1 --- Large sample properties of A and Ap --- p.35 / Chapter 3.1.2 --- Large sample properties of Ac and A --- p.36 / Chapter 3.2 --- Discussions --- p.37

Yu, Kai Shing. / "November 2010." / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 103-114). / Abstracts in English and Chinese. / Abstract --- p.2 / 中文摘要 --- p.6 / List of Contents --- p.9 / List of Table --- p.12 / Abbreviation --- p.13 / Acknowledgement --- p.14 / Chapter Chapter 1: --- Introduction --- p.15 / Chapter 1.1 --- Epidemiology of lung cancer --- p.15 / Chapter 1.2 --- Overview of significant prognostic factors for patients with NSCLC --- p.18 / Chapter 1.2.1 --- Tumor related factors --- p.19 / Chapter 1.2.2 --- Patient related factors --- p.21 / Chapter 1.3 --- Overview of significant prognostic factors for SCLC patients --- p.22 / Chapter Chapter 2: --- Literature Review --- p.25 / Chapter 2.1 --- Prevalence of co-morbidity among lung cancer patients --- p.25 / Chapter 2.2 --- Impact of co-morbidity on non small cell lung cancer patients --- p.28 / Chapter 2.3 --- Impact of co-morbidity on small cell lung cancer patients --- p.36 / Chapter 2.4 --- Summary of evidence from literature review --- p.40 / Chapter Chapter 3: --- Aim and Objectives --- p.42 / Chapter 3.1 --- General aim --- p.42 / Chapter 3.2 --- Specific objectives --- p.42 / Chapter 3.3 --- Main hypothesis --- p.42 / Chapter Chapter 4: --- Methodology --- p.43 / Chapter 4.1 --- Research design --- p.43 / Chapter 4.2 --- Study population --- p.43 / Chapter 4.3 --- Sample size estimation --- p.45 / Chapter 4.4 --- Data collection --- p.47 / Chapter 4.4.1 --- Demographic information --- p.47 / Chapter 4.4.2 --- Co-morbidity --- p.51 / Chapter 4.4.3 --- Adverse symptoms --- p.51 / Chapter 4.4.4 --- Disease characteristics --- p.52 / Chapter 4.4.5 --- Baseline laboratory findings --- p.53 / Chapter 4.4.6 --- Treatment data --- p.53 / Chapter 4.4.7 --- Follow up --- p.53 / Chapter 4.5 --- Statistical analyses --- p.54 / Chapter Chapter 5: --- Results --- p.56 / Chapter 5.1 --- Description of cohort --- p.56 / Chapter 5.2 --- Baseline characteristics --- p.58 / Chapter 5.3 --- Symptom presentation --- p.62 / Chapter 5.4 --- Histological characteristics --- p.64 / Chapter 5.5 --- Treatment characteristics --- p.67 / Chapter 5.6 --- Haematological characteristics of study population --- p.69 / Chapter 5.7 --- Prevalence of co-morbidity --- p.71 / Chapter 5.8 --- Overall survival --- p.74 / Chapter 5.8.1 --- Univariate and multivariate survival analysis for SCLC patients --- p.75 / Chapter 5.8.2 --- Univariate and multivariate survival analysis for NSCLC patients --- p.77 / Chapter 5.8.3 --- In-depth analyses for the Impact of co-morbidity on lung cancer survival --- p.79 / Chapter 5.8.4 --- Selected underlying causes of death --- p.84 / Chapter Chapter 6: --- Discussion --- p.85 / Chapter 6.1 --- Prognostic factors --- p.85 / Chapter 6.2 --- Prevalence of co-morbidity --- p.89 / Chapter 6.3 --- Impact of co-morbidity on lung cancer survival --- p.92 / Chapter 6.4 --- Strengths and limitations of this study --- p.97 / Chapter Chapter 7: --- Conclusions --- p.101 / Chapter Chapter 8: --- Implications and Recommendations for medial practice --- p.102 / References --- p.103

Orientador: Maria Coleta Ferreira Albino de Oliveira / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Filosofia e Ciências Humanas / Made available in DSpace on 2018-08-19T20:38:07Z (GMT). No. of bitstreams: 1 Pereira_PauloJose_D.pdf: 5437049 bytes, checksum: 8d1bb8135f9a3c5871d30cf359e8c115 (MD5) Previous issue date: 2012 / Resumo: O conceito de adoção varia de acordo com a época e com as tradições. E o tema, além de invadir a discussão de ordem moral, atinge diversas áreas do conhecimento, entre elas a Demografia. Com a evolução da legislação brasileira sobre adoção, principalmente no final do século XX, nota-se que a prioridade é a qualidade de vida da criança ou adolescente, dando-lhe o direito de ter uma família para protegê-lo e que seja capaz de propiciar seu desenvolvimento. Esta tese se debruça sobre essa questão, focalizando especificamente a transferência legal da parentalidade de crianças e adolescentes para adultos outros que não seus pais biológicos. Sua motivação central é a de responder ao seguinte questionamento: o perfil da criança ou adolescente declarado como disponível para adoção influencia no tempo de espera para que seja incorporado a uma nova família? É em torno dessa questão central que são abordados a interferência do Estado no ambiente familiar, a evolução da legislação, as mudanças dos níveis de fecundidade, as preferências dos candidatos a adotantes, o perfil das crianças e dos adolescentes que aguardam adoção e as características dos diversos tipos de famílias que já adotaram. Ainda com a finalidade de responder a questão central da tese, foram aplicadas técnicas de Análise de Sobrevivência para identificar, estatisticamente, a importância de variáveis como sexo, idade, cor da pele, entre outras, na determinação do tempo de espera para adoção de crianças e adolescentes que foram cadastrados nos Juizados de Infância e Juventude dos municípios de Recife e São Paulo. Fica evidente, ao final deste estudo, que além da criação do Cadastro Nacional de Adoção e ações que derrubem certos preconceitos existentes na sociedade, é necessário que haja políticas públicas abrangentes voltadas para o indivíduo e para a família. Só a união desses fatores pode levar o país a conviver com um número cada vez mais reduzido de crianças e adolescentes excluídos de uma convivência familiar, e também garantir uma vida com dignidade e oportunidades para aqueles que, inevitavelmente, crescerão e se formarão sob a tutela do Estado. Estudos futuros devem focalizar, cada vez mais com um olhar demográfico, as informações oficiais, em níveis nacionais, que envolvam não só as crianças e adolescentes aptos à adoção, mas também aqueles que vivem em abrigos com a situação jurídica indefinida, os pretendentes à adoção, os egressos que não foram adotados, as Varas de Infância e Juventude. Uma análise do fenômeno com um horizonte maior faz-se necessário, e com o efetivo funcionamento do Cadastro Nacional de Adoção e do Sistema de Informação para Infância e Adolescência, em um curto espaço de tempo isso poderá ser realizado / Abstract: The adoption varies according to the time, the traditions and the theme as well as discussing moral issues. The problematic reaches different areas of social science, including the Demography. With the evolution of Brazilian legislation on adoption, especially in the late 20th century, the priority is the quality of life of the adopted person, giving her the right of having a family for protection. Furthermore, a family would be able to foster the development to a full member of society. This thesis focuses on the legal transfer of parenting children and teens to adults other than their biological parents in the context of adoption. The main motivation is to clarify if the profile of the person available for adoption influences the waiting time to be incorporated into a new family. The central issues that are addressed are the interference in family environment, legislative developments, changes in fertility levels, preferences of prospective adopters, the profile of the person waiting for adoption as well as the characteristics of different types of families that have adopted a child. To investigate the described problematic and influences, techniques of survival analysis were applied to identify statistically the importance of variables such as sex, age, skin color by determining the waiting time for the adopted person which were enrolled in the Child and Youth Courts of the cities of Recife and São Paulo. This study reveals, that the creation of the National Register of Adoption as well as actions that bring down certain prejudices in society, must be aimed at the individual as well as the family. Only the union of these factors gives rise to a country with an increasingly small number of children and adolescents excluded from a family. Furthermore, this guarantees a life with dignity and opportunities for those who will inevitably grow and form under the tutelage of the State. Future studies should focus more on official demographic information at national levels, involving not only children and adolescents that are able to be adopted, but also those living in shelters with uncertain legal status, applicants for adoption grown up at the Children and Youth Courts. An analysis of the phenomenon with a longer time horizon needs to be done, and could be done with a more effective operation of the National Adoption Register and Information System for Children and Adolescents / Doutorado / Demografia / Doutor em Demografia

Orientador: Luiz Koodi Hotta / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Matematica, Estatistica e Computação Cientifica / Made available in DSpace on 2018-08-21T13:55:30Z (GMT). No. of bitstreams: 1 Tsai_Rodrigo_D.pdf: 3859687 bytes, checksum: 1064b1fa05b98307d97763bb79e95de4 (MD5) Previous issue date: 2012 / Resumo: Nesse trabalho discutimos aplicações de cópulas a modelos de riscos múltiplos com dependência e modelos de misturas de distribuições. Numa primeira parte analisamos a inclusão de dependência entre os fatores de risco do modelo de riscos múltiplos. Os modelos de riscos múltiplos são uma família de modelos flexíveis para representar dados de tempos de vida. Suas maiores vantagens sobre os modelos de risco simples incluem a habilidade de representar funções de taxa de falha com formas não usuais e a facilidade de incluir covariáveis. O objetivo principal dessa parte é modelar a dependência existente entre as causas latentes de falha do modelo de riscos múltiplos por meio de funções de cópulas. A escolha da função de cópulas bem como das funções de distribuição dos tempos latentes de falha resultam numa classe flexível de distribuições de sobrevivência que é capaz de representar funções de taxa de falha de formas multimodais, forma de banheira e contendo efeitos locais dados pela concorrência dos riscos. A identificação e estimação do modelo proposto também são discutidas. Ao eliminar a restrição de suporte positivo para as variáveis latentes, o método pode ser utilizado para gerar uma família rica de distribuições univariadas contendo assimetrias e múltiplas modas. Na segunda parte propomos um modelo de mistura de distribuições generalizado utilizando cópulas. O parâmetro da cópula é útil para definir formas de assimetria e ponderar com maior ou menor peso determinadas regiões do suporte das distribuições componentes para compor a mistura. pesos das distribuições componentes variam no suporte da distribuição e não são restritos à soma unitária. A modelagem resultante acrescenta uma maior flexibilidade aos modelos de misturas na representação de dados com densidades de várias formas multimodais e assimétricas. O modelo tem como casos particulares o modelo de mistura tradicional, o modelo de riscos múltiplos e o modelo de fração de cura. Os modelos são aplicados a dados simulados e reais da literatura. Foram utilizados os métodos de estimação de máxima verossimilhança e os critérios de ajuste de Akaike e Bayesiano para a seleção dos modelos. Os modelos representaram bem os conjuntos de dados analisados em comparação com metodologias propostas na literatura / Abstract: In this work, we discuss the application of copula to polyhazard and mixture models. First we analyse the inclusion of dependence among failure causes in the polyhazard models. The polyhazard models constitute a family of flexible models to represent lifetime data. Their main advantages over single hazard models include the ability to represent hazard rate functions with unusual shapes and the ease of including covariates. The main purpose in this first part is to model the dependence that exists among the latent causes of failure in the polyhazard model by copula functions. The choice of the copula function as well as the latent failure distributions produces a flexible class of survival distributions that is able to model hazard functions with unusual shapes such as bathtub or multimodal curves, while also modelling local effects given by the competing risks. The model identification and estimation are also discussed. Dropping the restriction of positive support for the latent variables, the method can be used to generate a rich family of univariate distributions with asymmetries and multiple modes. In the second part a generalized mixture model using copula functions is proposed. To assemble the mixture model, the parameter of the copula function is used to define asymmetry shapes and to attribute more or less weight to chosen regions of the component distributions. The weights of the component distributions vary on the support of the distribution and are not restricted to the unitary sum. The resulting model increases the flexibility of the mixture models to represent data with densities with several multimodal and asymmetric shapes. Special cases of the model are the traditional mixture models, the polyhazard model, and the cure fraction model. Simulated and empirical data from the literature are analysed by the proposed models. The estimation was done by maximum likelihood methods and the selection of the models used the Akaike and Bayesian criteria. The proposed models exhibited very good fit to the data sets in comparison to other methodologies presented in the literature / Doutorado / Estatistica / Doutor em Estatística

There has been an increasing interest in survival analysis with interval-censored data, where the event of interest (such as infection with a disease) is not observed exactly but only known to happen between two examination times. However, because so much research has been focused on right-censored data, so many statistical tests and techniques are available for right-censoring methods, hence interval-censoring methods are not as abundant as those for right-censored data. In this study, right-censoring methods are used to fit a proportional hazards model to some interval-censored data. Transformation of the interval-censored observations was done using a method called mid-point imputation, a method which assumes that an event occurs at some midpoint of its recorded interval. Results obtained gave conservative regression estimates but a comparison with the conventional methods showed that the estimates were not significantly different. However, the censoring mechanism and interval lengths should be given serious consideration before deciding on using mid-point imputation on interval-censored data.

Thesis (Ph.D. (Statistics)) -- University of Limpopo, 2022 / This thesis is based on application of frailty and copula models to under five child mortality data set in South Africa. The main purpose of the study was to apply sample splitting techniques in a survival analysis setting and compare clustered survival models considering left truncation to the under five child mortality data set in South Africa. The major contributions of this thesis is in the application of the shared frailty model and a class of Archimedean copulas in particular, Clayton-Oakes copula with completely monotone generator, and introduction of sample splitting techniques in a survival analysis setting. The findings based on shared frailty model show that clustering effect was sig nificant for modelling the determinants of time to death of under five children, and revealed the importance of accounting for clustering effect. The conclusion based on Clayton-Oakes model showed association between survival times of children from the same mother. It was found that the parameter estimates for the shared frailty and the Clayton-Oakes models were quite different and that the two models cannot be comparable. Gender, province, year, birth order and whether a child is part of twin or not were found to be significant factors affect ing under five child mortality in South Africa. / NRF-TDG Flemish Interuniversity Council Institutional corporation (VLIR-IUC) VLIR-IUC Programme of the University of Limpopo

Thesis (M.Sc. (Statistics)) -- University of Limpopo, 2020 / Peritoneal Dialysis (PD) is a process of replacing kidney function which cleans waste from the blood and remove extra fluid from the body. In most cases, the process of PD is slowed down by a peritoneal membrane infection called peritonitis. Despite recent advancements in treatments and prevention, peritonitis still remains the leading complication which results in high morbidity and technique failure among PD patients. Using a prospective peritonitis dataset of 159 kidney patients who were on PD from 2008 to 2015 in Pietersburg Provincial Hospital, the aim of this study was to identify potential social, demographic and biological risk factors that contribute to the first episode of peritonitis. Both semi-parametric (Cox PH) and parametric (Accelerated Failure Time: Weibull, exponential, loglogistic, and gamma) survival models were fitted to the peritonitis dataset. Akaike Information Criterion (AIC) was applied to select models which best fit to the peritonitis data. Accordingly, log-logistic Accelerated Failure Time (AFT) model was found to be a working model that best fit to the data. A total of 96 (60.38%) peritonitis cases were recorded over the follow-up period with majority of peritonitis infection coming from females (65.4%) and rural dwellers (65.7%) with (62.6%) of black Africans showing higher risk of developing peritonitis. The multivariate log-logistic AFT model revealed that availability of water (p-value=0.018), electricity (p-value=0.018), dwelling (p-value=0.008), haemoglobin status (p-value=0.002) and duration on PD (p-value=0.001) are significant risk factors for the development of peritonitis. Therefore, patients with no water and electricity, coming from rural background with low level of haemoglobin and shorter duration on PD are associii ated with high risk or hazard of developing peritonitis for the first time.

Change-point detection in hazard rate function is an important research topic in survival analysis. In this dissertation, we firstly review existing methods for single change-point detection in piecewise exponential hazard model. Then we consider the problem of estimating the change point in the presence of right censoring and long-term survivors while using Kaplan-Meier estimator for the susceptible proportion. The maximum likelihood estimators are shown to be consistent. Taking one step further, we propose an counting process based and least squares based change-point detection algorithm. For single change-point case, consistency results are obtained. We then consider the detection of multiple change-points in the presence of long-term survivors via maximum likelihood based and counting process based method. Last but not least, we use a weighted least squares based and counting process based method for detection of multiple change-points with long-term survivors and covariates. For multiple change-points detection, simulation studies show good performances of our estimators under various parameters settings for both methods. All methods are applied to real data analyses. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection