Dissertations / Theses on the topic 'Mixture cure model'
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Krachey, Elizabeth Catherine. "Variations on the Accelerated Failure Time Model: Mixture Distributions, Cure Rates, and Different Censoring Scenarios." NCSU, 2009. http://www.lib.ncsu.edu/theses/available/etd-08182009-102357/.
Full textErich, Roger Alan. "Regression Modeling of Time to Event Data Using the Ornstein-Uhlenbeck Process." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1342796812.
Full textSeppä, K. (Karri). "Quantifying regional variation in the survival of cancer patients." Doctoral thesis, Oulun yliopisto, 2012. http://urn.fi/urn:isbn:9789526200118.
Full textTiivistelmä Syöpäpotilaiden elossaolon alueellisen vaihtelun seuraaminen on tärkeää arvioitaessa syövänhoidon oikeudenmukaista jakautumista alueittain. Kun alueet ovat pieniä tai harvaan asuttuja, alueellisen kokonaisvaihtelun satunnainen osa kasvaa merkittäväksi. Tämän väitöstutkimuksen tavoitteena on kehittää menetelmiä, joilla pystytään arvioimaan maan sisäistä alueellista vaihtelua lisäkuolleisuudessa, jonka itse syöpä potilaille aiheuttaa, ja tiivistämään alueellisen vaihtelun kansanterveydellinen merkitys mittalukuihin, jotka ottavat kilpailevan kuolleisuuden huomioon ja ovat myös päättäjien tulkittavissa. Ehdotetuilla menetelmillä voidaan potilaiden ennustetta kuvailla käyttäen elossaolo-ajan keskiarvoa ja mediaania, vaikka potilaiden seuruu olisi keskeneräinen. Potilaiden syykohtaiselle kuolleisuudelle sovitetaan bayesiläisittäin MCMC-simulaatiota hyödyntäen malli, jossa parantuneiden potilaiden osuuden kuvaamisen lisäksi alueellinen vaihtelu esitetään kahden satunnaisefektijoukon avulla. Tämä hierarkkinen malli laajennetaan suhteellisen elossaolon estimointiin, jossa potilaiden odotettu elossaolo estimoidaan alueittain ja siihen liittyvä satunnaisvaihtelu otetaan huomioon. Alueellisen vaihtelun kansanterveydellistä merkitystä mitataan elossaoloajan keskimääräisellä pidentymällä sekä vältettävien kuolemien lukumäärällä, jotka voitaisiin saavuttaa, mikäli suotuisin suhteellisen elossaolon taso saavutettaisiin kaikilla alueilla. Kehitettyjä menetelmiä käytettiin Suomen Syöpärekisterin aineistojen analysointiin. Paksusuoli- ja kilpirauhassyöpäpotilaiden elinaikojen keskiarvojen ja mediaanien estimaatit oikaistiin harhasta, joka aiheutui potilaiden luontaisesta valikoitumisesta diagnosointijakson aikana iän suhteen. Parantuneiden osuuden satunnaisefektimalli mahdollisti rintasyöpäpotilaiden syykohtaisen kuolleisuuden ja paksusuolisyöpäpotilaiden suhteellisen elossaolon kuvaamisen vähäisellä määrällä parametreja ja antoi järkeenkäyvät estimaatit myös harvaan asutuille sairaanhoitopiireille
Kutal, Durga Hari. "Various Approaches on Parameter Estimation in Mixture and Non-mixture Cure Models." Thesis, Florida Atlantic University, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10929031.
Full textAnalyzing life-time data with long-term survivors is an important topic in medical application. Cure models are usually used to analyze survival data with the proportion of cure subjects or long-term survivors. In order to include the proportion of cure subjects, mixture and non-mixture cure models are considered. In this dissertation, we utilize both maximum likelihood and Bayesian methods to estimate model parameters. Simulation studies are carried out to verify the finite sample performance of the estimation methods. Real data analyses are reported to illustrate the goodness-of-fit via Fréchet, Weibull and Exponentiated Exponential susceptible distributions. Among the three parametric susceptible distributions, Fréchet is the most promising.
Next, we extend the non-mixture cure model to include a change point in a covariate for right censored data. The smoothed likelihood approach is used to address the problem of a log-likelihood function which is not differentiable with respect to the change point. The simulation study is based on the non-mixture change point cure model with an exponential distribution for the susceptible subjects. The simulation results revealed a convincing performance of the proposed method of estimation.
Weston, Claire Louise. "Applications of non-mixture cure models in childhood cancer studies." Thesis, University of Leicester, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.492826.
Full textWard, Alexander P. "Modelling Response Patterns for A Large-Scale Mail Survey Study Using Mixture Cure Models." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1555587554123989.
Full textCalsavara, Vinicius Fernando. "Modelos de sobrevivência com fração de cura usando um termo de fragilidade e tempo de vida Weibull modificada generalizada." Universidade Federal de São Carlos, 2011. https://repositorio.ufscar.br/handle/ufscar/4546.
Full textIn survival analysis, some studies are characterized by having a significant fraction of units that will never suffer the event of interest, even if accompanied by a long period of time. For the analysis of long-term data, we approach the standard mixture model by Berkson & Gage, where we assume the generalized modified Weibull distribution for the lifetime of individuals at risk. This model includes several classes of models as special cases, allowing its use to discriminate models. The standard mixture model implicitly assume that those individuals experiencing the event of interest possess homogeneous risk. Alternatively, we consider the standard mixture model with a frailty term in order to quantify the unobservable heterogeneity among individuals. This model is characterized by the inclusion of a unobservable random variable, which represents information that can not or have not been observed. We assume multiplicative frailty with a gamma distribution. For the lifetime of individuals at risk, we assume the Weibull distribution, obtaining the frailty Weibull standard mixture model. For both models, we realized simulation studies with the purpose of analyzing the frequentists properties of estimation procedures. Applications to real data set showed the applicability of the proposed models in which parameter estimates were determined using the approaches of maximum likelihood and Bayesian.
Em análise de sobrevivência determinados estudos caracterizam-se por apresentar uma fração significativa de unidades que nunca apresentarão o evento de interesse, mesmo se acompanhados por um longo período de tempo. Para a análise de dados com longa duração, abordamos o modelo de mistura padrão de Berkson & Gage supondo que os tempos de vida dos indivíduos em risco seguem distribuição Weibull modificada generalizada. Este modelo engloba diversas classes de modelos como casos particulares, propiciando o uso deste para discriminar modelos. O modelo abordado assume implicitamente que todos os indivíduos que falharam possuem risco homogêneo. Alternativamente, consideramos o modelo de mistura padrão com um termo de fragilidade com o objetivo de quantificar a heterogeneidade não observável entre os indivíduos. Este modelo é caracterizado pela inclusão de uma variável aleatória não observável, que representa as informações que não podem ou que não foram observadas. Assumimos que a fragilidade atua de forma multiplicativa com distribuição gama. Para os tempos de vida dos indivíduos em risco consideramos a distribuição Weibull, obtendo o modelo de mistura padrão Weibull com fragilidade. Para os dois modelos realizamos estudos de simulação com o objetivo de analisar as propriedades frequentistas dos processos de estimação. Aplicações a conjunto de dados reais mostraram a aplicabilidade dos modelos propostos, em que a estimação dos parâmetros foram determinadas através das abordagens de máxima verossimilhança e Bayesiana.
Pešout, Pavel. "Přístupy k shlukování funkčních dat." Doctoral thesis, Vysoká škola ekonomická v Praze, 2007. http://www.nusl.cz/ntk/nusl-77066.
Full textLee, Kyeong Eun. "Bayesian models for DNA microarray data analysis." Diss., Texas A&M University, 2005. http://hdl.handle.net/1969.1/2465.
Full textGouveia, Bruno Pauka. "Modelo de mistura padrão com tempos de vida exponenciais ponderados." Universidade Federal de São Carlos, 2010. https://repositorio.ufscar.br/handle/ufscar/4544.
Full textFinanciadora de Estudos e Projetos
In this work, we brie_y introduce the concepts of long-term survival analysis. We dedicated ourselves exclusively to the standard mixture cure model from Boag (1949) and Berkson & Gage (1952), showing its deduction and presenting the imunes probability function, which is taken from the model itself and we investigated the identi_ability issues of the mixture model. Motivated by the possibility that a experiment design can lead to a biased sample selection, we studied the weighted probability distributions, more speci_cally the weighted exponential distributions family and its properties. We studied two distributions that belong to this family; namely, the length biased exponential distribution and the beta exponential distribution. Using the GAMLSS package in R, we made some simulation studies intending to evidence the bias that occur when the possibility of a weighted sample is ignored.
Neste trabalho apresentamos brevemente os conceitos que de_nem a análise de sobreviv ência de longa duração. Dedicamo-nos exclusivamente ao modelo de mistura padrão de Boag (1949) e Berkson & Gage (1952), sendo que nos preocupamos com sua formulação, apresentamos a função probabilidade de imunes, que é derivada do próprio modelo e investigamos a questão da identi_cabilidade. Motivados pela possibilidade de que um planejamento experimental leve a uma seleção viciada da amostra, estudamos as distribui ções ponderadas de probabilidade, mais especi_camente a família das distribuições exponenciais ponderadas e suas propriedades. Estudamos duas distribuições pertencentes a essa família, a distribuição exponencial length biased e a distribuição beta exponencial. Fazendo uso do pacote GAMLSS em R, realizamos alguns estudos de simulação com o intuito de evidenciar o erro cometido quando se ignora a possibilidade de que a amostra seja proveniente de uma distribuição ponderada.
Sorin, Edouard. "Fissuration en modes mixtes dans le bois : diagnostic et évaluation des méthodes de renforcement local." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0264/document.
Full textThe purpose of reinforcing assemblies and structural elements inwood is to overcome the resistance limits of the material, by transferring greaterefforts in areas which can lead to premature cracking in structures. The reinforcementsused can be made of steel, composite materials or wood. Their hook can bemechanical (screwed bodies) or by adhesion (structural bonding like glued-in rodsfor example). In both cases, the transfer of solicitations remains poorly known, andthe effect of the beginning and the deflection of crack are not well apprehended. Inengineering techniques, the wood resistance in the reinforced area is neglected, whichis in line with the precautionary principle. Currently, the scientific investigations areinterested in the resistance of those kind of techniques without considering the interactionsbetween the quasi-brittle behavior of the wood and the reinforcementswhich govern the gain in mechanical performance. However, these solutions can leadto a failure caused by the progressive splitting of the wood and the anchor loss ofthe reinforcement. So it seems accurate to propose predictions of the short-termstrength for splitting of reinforced and unreinforced beams, which can be used tofurther exploration of the long-term failure mechanism. That is why, in this study, aglobal prediction model of the ultimate strength of structural components subjectedto splitting, reinforced and unreinforced ones, was developed. It considers the quasibrittlebehavior of the wood and crack propagation in mixed mode, using a mixinglaw established on the R-curves. The relevance of this modeling was then comparedto the current dimensioning methods of the Eurocodes 5, for notched beams, withexperimental campaigns conducted at different scales
Faria, Adriano Augusto de. "Essays in empirical finance." reponame:Repositório Institucional do FGV, 2017. http://hdl.handle.net/10438/19503.
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This thesis is a collection of essays in empirical finance mainly focused on term structure models. In the first three chapters, we developed methods to extract the yield curve from government and corporate bonds. We measure the performance of such methods in pricing, Value at Risk and forecasting exercises. In its turn, the last chapter brings a discussion about the effects of different metrics of the optimal portfolio on the estimation of a CCAPM model.In the first chapter, we propose a segmented model to deal with the seasonalities appearing in real yield curves. In different markets, the short end of the real yield curve is influenced by seasonalities of the price index that imply a lack of smoothness in this segment. Borrowing from the flexibility of spline models, a B-spline function is used to fit the short end of the yield curve, while the medium and the long end are captured by a parsimonious parametric four-factor exponential model. We illustrate the benefits of the proposed term structure model by estimating real yield curves in one of the biggest government index-linked bond markets in the world. Our model is simultaneously able to fit the yield curve and to provide unbiased Value at Risk estimates for different portfolios of bonds negotiated in this market.Chapter 2 introduces a novel framework for the estimation of corporate bond spreads based on mixture models. The modeling methodology allows us to enhance the informational content used to estimate the firm level term structure by clustering firms together using observable firm characteristics. Our model builds on the previous literature linking firm level characteristics to credit spreads. Specifically, we show that by clustering firms using their observable variables, instead of the traditional matrix pricing (cluster by rating/sector), it is possible to achieve gains of several orders of magnitude in terms of bond pricing. Empirically, we construct a large panel of firm level explanatory variables based on results from a handful of previous research and evaluate their performance in explaining credit spread differences. Relying on panel data regressions we identify the most significant factors driving the credit spreads to include in our term structure model. Using this selected sample, we show that our methodology significantly improves in sample fitting as well as produces reliable out of sample price estimations when compared to the traditional models.Chapter 3 brings the paper “Forecasting the Brazilian Term Structure Using Macroeconomic Factors”, published in Brazilian Review of Econometrics (BRE). This paper studies the forecasting of the Brazilian interest rate term structure using common factors from a wide database of macroeconomic series, from the period of January 2000 to May 2012. Firstly the model proposed by Moench (2008) is implemented, in which the dynamic of the short term interest rate is modeled using a Factor Augmented VAR and the term structure is derived using the restrictions implied by no-arbitrage. Similarly to the original study, this model resulted in better predictive performance when compared to the usual benchmarks, but presented deterioration of the results with increased maturity. To avoid this problem, we proposed that the dynamic of each rate be modeled in conjunction with the macroeconomic factors, thus eliminating the no-arbitrage restrictions. This attempt produced superior forecasting results. Finally, the macro factors were inserted in a parsimonious parametric three-factor exponential model.The last chapter presents the paper “Empirical Selection of Optimal Portfolios and its Influence in the Estimation of Kreps-Porteus Utility Function Parameters”, also published in BRE. This paper investigates the effects on the estimation of parameters related to the elasticity of intertemporal substitution and risk aversion, of the selection of different portfolios to represent the optimal aggregate wealth endogenously derived in equilibrium models with Kreps-Porteus recursive utility. We argue that the usual stock market wide index is not a good portfolio to represent optimal wealth of the representative agent, and we propose as an alternative the portfolio from the Investment Fund Industry. Especially for Brazil, where that industry invests most of its resources in fixed income, the aforementioned substitution of the optimal proxy portfolio caused a significant increase in the risk aversion coefficient and the elasticity of the intertemporal substitution in consumption.
Prabel, Benoit. "MODÉLISATION AVEC LA MÉTHODE X-FEM DE LA PROPAGATION DYNAMIQUE ET DE L'ARRÊT DE FISSURE DE CLIVAGE DANS UN ACIER DE CUVE REP." Phd thesis, INSA de Lyon, 2007. http://tel.archives-ouvertes.fr/tel-00278939.
Full text蔡長宇. "Semiparametric analysis for mixture cure model using prevalent survival data." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/26453975967007014919.
Full textHuang, Wei-Lun, and 黃韋倫. "Semiparametric Analysis of Transformation Mixture Cure Models for Interval-censored Data." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/74t8xb.
Full text國立陽明大學
公共衛生研究所
106
Interval-censored data arise when individuals are observed periodically, and we only know that the event occurs at a certain interval. In this thesis, we consider the mixed-case interval-censored data. Because the medical treatment has progressed greatly, some patients can be cured for some diseases. In genetic epidemiology, the subjects will be nonsusceptible to certain genetic diseases, when they do not have the specific genes related to the diseases. To analyze this type of data, we propose the transformation mixture cure models, in which the first part is a logistic regression model fitting the probability of cure, and the second part is a semiparametric transformation model for the event time of the non-cured people. In addition, the transformation model includes the Cox proportional hazard model and the proportional odds model. We develop an EM algorithm to obtain the semiparametric maximum likelihood estimators and estimate the variance of the estimates of parameters with profile likelihood. In the simulation studies, we conduct the practical scenarios to evaluate the performance of the proposed approach. Finally, we apply the proposed approach to analyze the data of HIV-1 infection among persons with hemophilia.