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Dissertations / Theses on the topic 'Discrete time survival analysis'

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Published: 4 June 2021

Last updated: 15 February 2022

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1

Denson, Kathleen. "Factors Affecting Discrete-Time Survival Analysis Parameter Estimation and Model Fit Statistics." Thesis, University of North Texas, 1998. https://digital.library.unt.edu/ark:/67531/metadc278405/.

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Discrete-time survival analysis as an educational research technique has focused on analysing and interpretating parameter estimates. The purpose of this study was to examine the effects of certain data characteristics on the hazard estimates and goodness of fit statistics. Fifty-four simulated data sets were crossed with four conditions in a 2 (time period) by 3 (distribution of Y = 1) by 3 (distribution of Y = 0) by 3 (sample size) design.

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2

Akbayin, Bercem. "The Treatment Effect of the City Connects Intervention on Exiting Limited English Proficiency Status." Thesis, Boston College, 2017. http://hdl.handle.net/2345/bc-ir:107654.

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Thesis advisor: Henry I. Braun<br>The City Connects intervention is motivated by the belief that out-of-school factors act as barriers to student thriving in cognitive and non-cognitive domains. It seeks to address these barriers first by identifying each student’s strengths and needs and then by providing a tailored set of prevention, intervention, and enrichment programs. Underlying the program is the assumption that provision of high-quality resources and individualized services will enable children to be cognitively, socio-emotionally, and physically prepared to thrive in school. This study’s purpose was to estimate the effects of the City Connects intervention on English learners’ (EL) likelihood of exiting Limited English Proficiency (LEP) status. ELs comprise a student subpopulation most at-risk to fail academically, and exposure to the program was hypothesized to improve their likelihood of exiting LEP status earlier than otherwise. A series of one- and two-level discrete-time event history analyses were conducted on the main analytic sample as well as two sub-samples. As participation in City Connects is at the school-level, school-level matching was used for sub-samples 1 and 2, and propensity score weights were applied at the student-level for all three samples. Additionally, hazard probabilities, survival probabilities, cumulative hazard rates, and median lifetimes were estimated. Lastly, a sensitivity analysis was conducted to examine whether effects were robust to unobserved selection bias. The results indicated that ELs participating in the City Connects intervention were significantly more likely to exit LEP status earlier than their peers in comparison schools. The median time in LEP status in City Connects schools was shorter and translated into a gain of at least one half of a year in grade in mainstream classes. Also, all the fitted models indicated that approximately 10 percent more City Connects students exited LEP status by the end of fifth grade than comparison students. Findings highlight the impact of the City Connects intervention, as ELs entering mainstream classes earlier could translate into important academic and non-academic gains, such as improved academic achievement and increased self-confidence<br>Thesis (PhD) — Boston College, 2017<br>Submitted to: Boston College. Lynch School of Education<br>Discipline: Educational Research, Measurement and Evaluation

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Threatt-Milton, G. Iris. "Application of discrete time survival analysis to examine minority undergraduate retention, attrition, and persistence to graduation at selected institutions." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0010059.

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4

Nygren, Emma. "The effect of peacekeeping operation on conflict intensity when taking into account foreign state sponsorship : A Discrete-Time Survival Analysis." Thesis, Uppsala universitet, Institutionen för freds- och konfliktforskning, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-443725.

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The answer to if peacekeeping is successful or not is still debated. The focus has mostly been on internal characteristics of peacekeeping missions. While external factors, have been largely overlooked. This thesis aims to explore the effects external involvement in intrastate conflicts may have on the success of peacekeeping deployment. It poses the following research question: how does foreign state sponsorship to rebel groups affect the success of peacekeeping operations? The main argument made is that the causal mechanisms presented for why peacekeeping operations are effective, do not have an effect on the sponsors and their incentive to stop fighting. Hence, it is hypothesized that peacekeeping operations are less effective in decreasing the duration of intrastate armed conflict when rebel groups are sponsored by foreign states. The argument is tested using a discrete-time survival analysis and Cox proportional hazard models on all intrastate conflicts between 1970-2017, and foreign state sponsorship is treated as an interaction effect. The findings did not support the hypothesis but rather suggest that the presence of peacekeepers has a dominant positive conflict-intensity reducing effect. These results scratch the surface of what the effects external involvement may have on peacekeeping success and indicate that peacekeeping is successfully undermining sponsorship.

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5

Ye, Hong. "Comparison of Cox regression and discrete time survival models." Thesis, Wayne State University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10153426.

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<p> A standard analysis of prostate cancer biochemical failure data is done by conducting two approaches in which risk factors or covariates are measured. Cox regression and discrete-time survival models were compared under different attributes: sample size, time periods, and parameters in the model. The person-period data was reconstructed when examining the same data in discrete-time survival model. Twenty-four numerical examples covering a variety of sample sizes, time periods, and number of parameters displayed the closeness of Cox regression and discrete-time survival methods in situations typical of the cancer study. </p>

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6

Kim, Sunha. "A Comparison of Discrete and Continuous Survival Analysis." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/47933.

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There has been confusion in choosing a proper survival model between two popular survival models of discrete and continuous survival analysis. This study aimed to provide empirical outcomes of two survival models in educational contexts and suggest a guideline for researchers who should adopt a suitable survival model. For the model specification, the study paid attention to three factors of time metrics, censoring proportions, and sample sizes. To arrive at comprehensive understanding of the three factors, the study investigated the separate and combined effect of these factors. Furthermore, to understand the interaction mechanism of those factors, this study examined the role of the factors to determine hazard rates which have been known to cause the discrepancies between discrete and continuous survival models. To provide empirical evidence from different combinations of the factors in the use of survival analysis, this study built a series of discrete and continuous survival models using secondary data and simulated data. In the first study, using empirical data from the National Longitudinal Survey of Youth 1997 (NLSY97), this study compared analyses results from the two models having different sizes of time metrics. In the second study, by having various specifications with combination of two other factors of censoring proportions and sample sizes, this study simulated datasets to build two models and compared the analysis results. The major finding of the study is that discrete models are recommended in the conditions of large units of time metrics, low censoring proportion, or small sample sizes. Particularly, discrete model produced better outcomes for conditions with low censoring proportion (20%) and small number (i.e., four) of large time metrics (i.e., year) regardless of sample sizes. Close examination of those conditions of time metrics, censoring proportion, and sample sizes showed that the conditions resulted into high hazards (i.e., 0.20). In conclusion, to determine a proper model, it is recommended to examine hazards of each of the time units with the specific factors of time metrics, censoring proportion and sample sizes.<br>Ph. D.

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7

Holm, Jens Christian. "Spinors in discrete space-time." Thesis, Georgia Institute of Technology, 1985. http://hdl.handle.net/1853/27901.

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Duchesne, Thierry. "Multiple time scales in survival analysis." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0002/NQ44759.pdf.

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9

Eliiyi, Ugur. "Discrete-time Stochastic Analysis Of Land Combat." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/759472/index.pdf.

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In this study, we present the implementation and experimental analysis of a modeling approach for analyzing tactical level land combat to generate information for weapon and ammunition planning. The discrete-time stochastic model (DSM), which can handle small and moderately large force levels, is based on single shot kill probabilities. Forces are assumed to be heterogeneous on both sides, and both directed and area fire types are modeled by means of combinatorial analysis. DSM considers overkills and can handle noncombat loss and engagement processes, discrete reinforcements, force combinations and divisions. In addition to experimenting with DSM, we estimate attrition rate coefficients used in Lanchester combat models, such that the two models will yield similar figures for force levels throughout the combat.

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Rosenberg, Magdalena. "Survival Time : A Survey on the Current Survival Time for an Unprotected Public System." Thesis, Högskolan i Halmstad, Sektionen för Informationsvetenskap, Data– och Elektroteknik (IDE), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-23199.

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Survival Time, what exactly does the term imply and what is the best method to measure it? Several experts within the field of Internet security have used the term; some has gone further and presented statistical facts on the survival time throughout the years. This bachelor thesis aim to present a universal definition of the term and further on measure the current survival time for a given unprotected system. By the deployment of a decoy, data will be captured and collected through port monitoring. Mainly focus will lie on building a time curve presenting the estimated time for an unprotected public system to get detected on the Internet and the elapsed time hence the system gets attacked.

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11

林國輝 and Kwok-fai Lam. "Topics in survival analysis." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1994. http://hub.hku.hk/bib/B30408994.

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Lam, Kwok-fai. "Topics in survival analysis /." Hong Kong : University of Hong Kong, 1994. http://sunzi.lib.hku.hk/hkuto/record.jsp?B13829919.

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Meier, Amalia Sophia. "Discrete proportional hazards models for uncertain outcomes /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/9579.

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Gorti, Bhaskar M. "Techniques for discrete, time domain system identification." Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-11242009-020121/.

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Gibson, Erika Lynn. "Continuous time multi-state models for survival analysis." Winston-Salem, NC : Wake Forest University, 2008. http://dspace.zsr.wfu.edu/jspui/handle/10339/37482.

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尹再英 and Choi-ying Wan. "Statistical analysis for capture-recapture experiments in discrete time." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B31225287.

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Wan, Choi-ying. "Statistical analysis for capture-recapture experiments in discrete time." Hong Kong : University of Hong Kong, 2001. http://sunzi.lib.hku.hk/hkuto/record.jsp?B22753217.

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Silva, Isabel Maria Marques da. "Contributions to the analysis of discrete-valued time series." Tese, Universidade do Porto. Reitoria, 2005. http://hdl.handle.net/10216/9742.

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Dissertação de Doutoramento em Matemática Aplicada apresentada à Faculdade de Ciências da Universidade do Porto<br>Séries temporais de contagem, categóricas ou binárias são exemplos de séries temporaisde valor discreto que aparecem frequentemente na prática. No entanto, uma vezque estas séries apresentam valores que pertencem a conjuntos finitos ou infinitosnumeráveis, os métodos tradicionais utilizados na análise de séries temporais não sãoadequados.Vários modelos para processos estacionários com distribuição marginal discreta têmsido propostos. Um desses modelos, particularmente usado para séries de contagem,são os processos Auto-Regressivos de valor INteiro de ordem p, denotados por INAR(p).Na primeira parte desta tese, os processos INAR são estudados quer no contexto deuma única série temporal, quer de réplicas da mesma série temporal. As principaiscaracterísticas destes modelos são apresentadas e exploradas de modo a obter métodosde estimação mais robustos. Por exemplo, as estatísticas de ordem superior forneceminformação adicional sobre os processos INAR porque estes são processos não lineares.Assim, são propostos dois métodos de estimação baseados em momentos e cumulantesde terceira ordem. Por outro lado, a utilização do critério de Whittle como métodode estimação é justificada através da propriedade mixing dos processos INAR. Mais,o critério automático para selecção de ordem baseado na versão corrigida do Critériode Informação de Akaike (AICC) é estabelecido para processos INAR. Extensos estudosde simulação investigam e comparam o desempenho dos diferentes estimadorespropostos, assim como do critério de selecção de ordem.Dados reais de contagem (duas séries temporais associadas a aplicações médicas eum conjunto de réplicas relacionadas com a astronomia) são analisados considerandoa metodologia subjacente aos modelos INAR. Verifica-se que a classe dos modelosINAR é adequada para a descrição dos dados.Existem séries temporais que apresentam mudanças abruptas, formas descontínuasou cujos valores pertencem a um conjunto finito discreto. Nestes casos, ...

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Silva, Isabel Maria Marques da. "Contributions to the analysis of discrete-valued time series." Doctoral thesis, Universidade do Porto. Reitoria, 2005. http://hdl.handle.net/10216/9742.

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Dissertação de Doutoramento em Matemática Aplicada apresentada à Faculdade de Ciências da Universidade do Porto<br>Séries temporais de contagem, categóricas ou binárias são exemplos de séries temporaisde valor discreto que aparecem frequentemente na prática. No entanto, uma vezque estas séries apresentam valores que pertencem a conjuntos finitos ou infinitosnumeráveis, os métodos tradicionais utilizados na análise de séries temporais não sãoadequados.Vários modelos para processos estacionários com distribuição marginal discreta têmsido propostos. Um desses modelos, particularmente usado para séries de contagem,são os processos Auto-Regressivos de valor INteiro de ordem p, denotados por INAR(p).Na primeira parte desta tese, os processos INAR são estudados quer no contexto deuma única série temporal, quer de réplicas da mesma série temporal. As principaiscaracterísticas destes modelos são apresentadas e exploradas de modo a obter métodosde estimação mais robustos. Por exemplo, as estatísticas de ordem superior forneceminformação adicional sobre os processos INAR porque estes são processos não lineares.Assim, são propostos dois métodos de estimação baseados em momentos e cumulantesde terceira ordem. Por outro lado, a utilização do critério de Whittle como métodode estimação é justificada através da propriedade mixing dos processos INAR. Mais,o critério automático para selecção de ordem baseado na versão corrigida do Critériode Informação de Akaike (AICC) é estabelecido para processos INAR. Extensos estudosde simulação investigam e comparam o desempenho dos diferentes estimadorespropostos, assim como do critério de selecção de ordem.Dados reais de contagem (duas séries temporais associadas a aplicações médicas eum conjunto de réplicas relacionadas com a astronomia) são analisados considerandoa metodologia subjacente aos modelos INAR. Verifica-se que a classe dos modelosINAR é adequada para a descrição dos dados.Existem séries temporais que apresentam mudanças abruptas, formas descontínuasou cujos valores pertencem a um conjunto finito discreto. Nestes casos, ...

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Silva, Isabel Maria Marques da. "Contributions to the analysis of discrete-valued time series." Doctoral thesis, Universidade do Porto. Reitoria, 2005. https://repositorio-aberto.up.pt/handle/10216/91963.

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Séries temporais de contagem, categóricas ou binárias são exemplos de séries temporais de valor discreto que aparecem frequentemente na prática. No entanto, uma vez que estas séries apresentam valores que pertencem a conjuntos finitos ou infinitos numeráveis, os métodos tradicionais utilizados na análise de séries temporais não são adequados.Vários modelos para processos estacionários com distribuição marginal discreta têm sido propostos. Um desses modelos, particularmente usado para séries de contagem, são os processos Auto-Regressivos de valor INteiro de ordem p, denotados por INAR(p). Na primeira parte desta tese, os processos INAR são estudados quer no contexto de uma única série temporal, quer de réplicas da mesma série temporal. As principais características destes modelos são apresentadas e exploradas de modo a obter métodos de estimação mais robustos. Por exemplo, as estatísticas de ordem superior fornecem informação adicional sobre os processos INAR porque estes são processos não lineares. Assim, são propostos dois métodos de estimação baseados em momentos e cumulantes de terceira ordem. Por outro lado, a utilização do critério de Whittle como método de estimação é justificada através da propriedade mixing dos processos INAR. Mais, o critério automático para selecção de ordem baseado na versão corrigida do Critério de Informação de Akaike (AICC) é estabelecido para processos INAR. Extensos estudos de simulação investigam e comparam o desempenho dos diferentes estimadores propostos, assim como do critério de selecção de ordem.Dados reais de contagem (duas séries temporais associadas a aplicações médicas e um conjunto de réplicas relacionadas com a astronomia) são analisados considerando a metodologia subjacente aos modelos INAR. Verifica-se que a classe dos modelos INAR é adequada para a descrição dos dados.Existem séries temporais que apresentam mudanças abruptas, formas descontínuas ou cujos valores pertencem a um conjunto finito discreto. Nestes casos, faz mais sentido (estatístico) aplicar a análise espectral de Walsh-Fourier para caracterizar os dados através das funções de Walsh (ondas quadradas). É um procedimento análogo à análise de Fourier, que caracteriza a variação periódica de séries temporais contínuas.Considerando que durante uma intervenção cirúrgica um paciente passa por vários níveis de relaxamento muscular, na segunda parte desta tese investiga-se em que medida a análise de Walsh-Fourier pode contribuir para melhorar a construção de um sistema de controlo adaptativo, em tempo real, para o bloqueio neuromuscular. Verifica-se que a análise espectral de Walsh-Fourier caracteriza a resposta induzida por um bolus administrado no início da anestesia. Esta caracterização conduz à estimação robusta dos parâmetros do controlador e é adequada para uso em ambiente clínico.<br>Discrete-valued time series are common in practice, yet methods for their analysis have been developed only recently. The fact that the variables take values on a finite or countably infinite set renders the traditional representations of dependence either impossible or impractical.Several models for stationary processes with discrete marginal distributions have been proposed. The first part of this thesis is concerned with the INteger-valued AutoRegressive, INAR(p), process, both in the context of a single and of replicated time series. The principal characteristics of the INAR(p) processes are reviewed and explored in order to improve the analysis of this process by providing new and powerful estimation methods for the parameters. For instance, since the INAR(p) process is not linear, high-order statistics provide additional information for the process. Thus, two estimation methods based on third-order moments and cumulants are proposed. On the other hand, the Whittle estimation is justified by the mixing property satisfied by the INAR(p) process. Furthermore, an automatic criterion for order selection, based on the corrected version of the Akaike Information Criterion (AICC), is established in the INAR framework. The small sample properties of the criterion for order selection as well as of the estimators proposed are comprehensively analyzed using simulation.INAR processes are fitted to three data sets: two single time series concerning with medical applications and a set of two replicates of astronomical time series. It is found that the class of INAR models is suitable for the description of the data.Walsh-Fourier spectral analysis (WFA) is a procedure used to analyze time series, specially when sharp discontinuities and changes of level occur in the data. The procedure is similar to the well known Fourier analysis, that characterizes the periodic variation in a continuous signal. Considering that during the surgical intervention a patient attains different levels of neuromuscular blockade, in the second part of the thesis the contribution of WFA to the design of an on-line adaptive control system for neuromuscular blockade is investigated.WFA provides a characterization of the neuromuscular blockade response induced by an initial bolus given at the beginning of anaesthesia, leading to robust controller parameter estimation suitable for use in a clinical environment.

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Nieto-Barajas, Luis E. "Bayesian nonparametric survival analysis via Markov processes." Thesis, University of Bath, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343767.

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Wang, Chao, and 王超. "Statistical inference for some discrete-valued time series." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B48329514.

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Some problems of' statistical inference for discrete-valued time series are investigated in this study. New statistical theories and methods are developed which may aid us in gaining more insight into the understanding of discrete-valued time series data. The first part is concerned with the measurement of the serial dependence of binary time series. In early studies the classical autocorrelation function was used, which, however, may not be an effective and informative means of revealing the dependence feature of a binary time series. Recently, the autopersistence function has been proposed as an alternative to the autocorrelation function for binary time series. The theoretical autopersistence functions and their sample analogues, the autopersistence graphs, are studied within a binary autoregressive model. Some properties of the autopcrsistencc functions and the asymptotic properties of the autopersistence graphs are discussed, justifying that the antopersistence graphs can be used to assess the dependence feature. Besides binary time series, intcger-vall1ed time series arc perhaps the most commonly seen discrete-valued time series. A generalization of the Poisson autoregression model for non-negative integer-valued time series is proposed by imposing an additional threshold structure on the latent mean process of the Poisson autoregression. The geometric ergodicity of the threshold Poisson autoregression with perburbations in the latent mean process and the stochastic stability of the threshold Poisson autoregression are obtained. The maximum likelihood estimator for the parameters is discussed and the conditions for its consistency and asymptotic normally are given as well. Furthermore, there is an increasing need for models of integer-valued time series which can accommodate series with negative observations and dependence structure more complicated than that of an autoregression or a moving average. In this regard, an integer-valued autoregressive moving average process induced by the so-called signed thinning operator is proposed. The first-order model is studied in detail. The conditions for the existence of stationary solution and the existence of finite moments are discussed under general assumptions. Under some further assumptions about the signed thinning operators and the distribution of the innovation, a moment-based estimator for the parameters is proposed, whose consistency and asymptotic normality are also proved. The problem of conducting one-step-ahead forecast is also considered based on hidden Markov chain theory. Simulation studies arc conducted to demonstrate the validity of the theories and methods established above. Real data analysis such as the annual counts of major earthquakes data are also presented to show their potential usefulness in applications.<br>published_or_final_version<br>Statistics and Actuarial Science<br>Doctoral<br>Doctor of Philosophy

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Hollman, Jorge. "Step by step eigenvalue analysis with EMTP discrete time solutions." Thesis, University of British Columbia, 2006. http://hdl.handle.net/2429/67.

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The present work introduces a methodology to obtain a discrete time state space representation of an electrical network using the nodal [G] matrix of the Electromagnetic Transients Program (EMTP) solution. This is the first time the connection between the EMTP nodal analysis solution and a corresponding state-space formulation is presented. Compared to conventional state space solutions, the nodal EMTP solution is computationally much more efficient. Compared to the phasor solutions used in transient stability analysis, the proposed approach captures a much wider range of eigenvalues and system operating states. A fundamental advantage of extracting the system eigenvalues directly from the EMTP solution is the ability of the EMTP to follow the characteristics of nonlinearities. The system's trajectory can be accurately traced and the calculated eigenvalues and eigenvectors correctly represent the system's instantaneous dynamics. In addition, the algorithm can be used as a tool to identify network partitioning subsystems suitable for real-time hybrid power system simulator environments, including the implementation of multi-time scale solutions. The proposed technique can be implemented as an extension to any EMTP-based simulator. Within our UBC research group, it is aimed at extending the capabilities of our real-time PC-cluster Object Virtual Network Integrator (OVNI) simulator.

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Schleyer, Marc. "Discrete time analysis of batch processes in material flow systems." Karlsruhe : Univ.-Verl. Karlsruhe, 2007. http://www.uvka.de/univerlag/volltexte/2007/243/.

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Ouaknine, Joel. "Discrete analysis of continuous behaviour in real-time concurrent systems." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365293.

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Jeong, Daehwa. "Analysis and design of a discrete time repetitive control system /." Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/7079.

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REBELLO, ALEXANDRE PEIXOTO. "REAL OPTIONS ANALYSIS IN DISCRETE TIME AN APPLICATION TO RETAIL." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2007. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=11342@1.

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CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO<br>As grandes redes varejistas brasileiras vêm passando por um momento de forte expansão geográfica, que tem por objetivo aumentar o valor das empresas através de ganhos de escala e aumento do poder de negociação frente aos fornecedores. A entrada em um novo mercado geográfico, no entanto, apresenta inúmeras incertezas que podem afetar a rentabilidade destas novas lojas. O método tradicional de avaliação pelo fluxo de caixa descontado usualmente utilizado para a abertura de novas lojas, não considera que a abertura de uma primeira loja traz novas informações de mercado que permitem ao investidor otimizar a sua estratégia de penetração neste mercado. Essa dissertação propõe a utilização da Teoria de Opções Reais para avaliar o projeto de expansão de uma rede de varejo para uma nova cidade, através da valoração das flexibilidades gerenciais de expansão e abandono disponíveis para a empresa. O modelo proposto, ao incorporar o valor da operação de uma segunda loja no caso de exercício da opção de expansão, aumenta o valor total do projeto quando comparado ao valor presente líquido calculado pelo método do Fluxo de Caixa Descontado, onde a decisão definitiva seria abrir apenas uma loja. A Teoria de Opções Reais mostrou-se superior na avaliação do projeto, pois o valor do projeto calculado pelo método do Fluxo de Caixa Descontado está subestimado ao não considerar as flexibilidades existentes no projeto.<br>The large Brazilian retail companies are undergoing strong geographical expansion in order to enhance shareholders value by gains of scale and greater negotiation power with suppliers. The entrance into a new geographical market, however, presents many uncertainties that can affect the return of these new stores. The traditional approach of discounted cash flow method, does not take into account that the opening of the first new store reveals new market information that allows the investor to optimize his penetration strategy in this market. This dissertation proposes the use of the Real Options Theory to value the project to expand a retail company to a new market, by valuing the managerial flexibility of expansion and abandonment available to the company. By incorporating the value of the operation of a second store in case of the exercise of the expansion option , the proposed model increases the total value of the project when compared to the net present value calculated by the discounted cash flow analysis. The Real Options Theory was superior in the project valuation as the value of the project calculated by the discounted cash flow analysis is underestimated by not considering the existing flexibility in the project.

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Pebes, Trujillo Miguel Raúl. "An application of discrete time survival models to analyze student dropouts at a private university in Peru." Master's thesis, Pontificia Universidad Católica del Perú, 2015. http://tesis.pucp.edu.pe/repositorio/handle/123456789/6992.

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Discrete-time survival models are discussed and applied to the study of which factors are associated with student dropouts at a private university in Lima, Per_u. We studied the characteristics of 26; 790 incoming students enrolled between 2004 and 2012 in all the under-graduate programs at the University. The analysis include the estimation of the survival and hazard functions using the Kaplan-Meier method and the _tting of parametric models using the Cox proportional hazards regression and the Logistic regression for survival analysis, this last one, in order to include time varying variables as predictors. During the period of analysis, the cumulative probability of remain at the University after _ve years was 73.7% [95% CI: 73.1% - 74.4%]. In any period the hazard is greater than 4.4% and this highest value is reached in the 3rd semester. In a multivariate analysis, we found that academic factors (area of study, type of admission, standardized academic performance index, and the percentage of passed credits); economic factors (type of residence, and payment scale); and sociodemographic factors (mother education level, indicators of whether or not parents are alive, and the age of the student) were associated with the risk of dropout.<br>Tesis

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Qiu, Feiyou. "JOINT MODELING OF LONGITUDINAL DATA AND DISCRETE-TIME SURVIVAL OUTCOME WITH APPLICATION TO STUDYING TUBERCULOSIS IMMUNOLOGY DATA." Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1322846245.

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Olivi, Alessandro. "Survival analysis of gas turbine components." Thesis, Linköpings universitet, Statistik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-129707.

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Survival analysis is applied on mechanical components installed in gas turbines. We use field experience data collected from repair inspection reports. These data are highly censored since the exact time-to-event is unknown. We only know that it lies before or after the repair inspection time. As event we consider irreparability level of the mechanical components. The aim is to estimate survival functions that depend on the different environmental attributes of the sites where the gas turbines operate. Then, the goal is to use this information to obtain optimal time points for preventive maintenance. Optimal times are calculated with respect to the minimization of a cost function which considers expected costs of preventive and corrective maintenance. Another aim is the investigation of the effect of five different failure modes on the component lifetime. The methods used are based on the Weibull distribution, in particular we apply the Bayesian Weibull AFT model and the Bayesian Generalized Weibull model. The latter is preferable for its greater flexibility and better performance. Results reveal that components from gas turbines located in a heavy industrial environment at a higher distance from sea tend to have shorter lifetime. Then, failure mode A seems to be the most harmful for the component lifetime. The model used is capable of predicting customer-specific optimal replacement times based on the effect of environmental attributes. Predictions can be also extended for new components installed at new customer sites.

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Hosoe, Yohei. "Discrete-Time Noncausal Linear Periodically Time-Varying Scaling for Robustness Analysis and Controller Synthesis." 京都大学 (Kyoto University), 2013. http://hdl.handle.net/2433/180502.

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van, Miltenburg Jelle. "Conformal survival predictions at a user-controlled time point : The introduction of time point specialized Conformal Random Survival Forests." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-232060.

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The goal of this research is to expand the field of conformal predictions using Random Survival Forests. The standard Conformal Random Survival Forest can predict with a fixed certainty whether something will survive up until a certain time point. This research is the first to show that there is little practical use in the standard Conformal Random Survival Forest algorithm. It turns out that the confidence guarantees of the conformal prediction framework are violated if the Standard algorithm makes predictions for a user-controlled fixed time point. To solve this challenge, this thesis proposes two algorithms that specialize in conformal predictions for a fixed point in time: a Fixed Time algorithm and a Hybrid algorithm. Both algorithms transform the survival data that is used by the split evaluation metric in the Random Survival Forest algorithm. The algorithms are evaluated and compared along six different set prediction evaluation criteria. The prediction performance of the Hybrid algorithm outperforms the prediction performance of the Fixed Time algorithm in most cases. Furthermore, the Hybrid algorithm is more stable than the Fixed Time algorithm when the predicting job extends to various time points. The hybrid Conformal Random Survival Forest should thus be considered by anyone who wants to make conformal survival predictions at usercontrolled time points.<br>Målet med denna avhandling är att utöka området för konformitetsprediktion med hjälp av Random Survival Forests. Standardutförandet av Conformal Random Survival Forest kan förutsäga med en viss säkerhet om någonting kommer att överleva fram till en viss tidpunkt. Denna avhandling är den första som visar att det finns liten praktisk användning i standardutförandet av Conformal Random Survival Forest-algoritmen. Det visar sig att konfidensgarantierna för konformitetsprediktionsramverket bryts om standardalgoritmen gör förutsägelser för en användarstyrd fast tidpunkt. För att lösa denna utmaning, föreslår denna avhandling två algoritmer som specialiserar sig i konformitetsprediktion för en bestämd tidpunkt: en fast-tids algoritm och en hybridalgoritm. Båda algoritmerna omvandlar den överlevnadsdata som används av den delade utvärderingsmetoden i Random Survival Forest-algoritmen. Uppskattningsförmågan för hybridalgoritmen överträffar den för fast-tids algoritmen i de flesta fall. Dessutom är hybrid algoritmen stabilare än fast-tids algoritmen när det förutsägelsejobbet sträcker sig till olika tidpunkter. Hybridalgoritmen för Conformal Random Survival Forest bör därför föredras av den som vill göra konformitetsprediktion av överlevnad vid användarstyrda tidpunkter.

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33

Gupta, Anurag. "Performance analysis of "Time Wrap" mechanism for parallel discrete event simulation." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/9218.

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Ngalamulume, Mulumba Chizmar John F. "College absenteeism economic model and multi-spell-discrete-time hazard analysis /." Normal, Ill. Illinois State University, 1997. http://wwwlib.umi.com/cr/ilstu/fullcit?p9803730.

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Thesis (D.A.)--Illinois State University, 1997.<br>Title from title page screen, viewed June 5, 2006. Dissertation Committee: John F. Chizmar (chair), Dean Hiebert, Mark Walbert. Includes bibliographical references (leaves 38-42) and abstract. Also available in print.

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35

Han, Lu. "Statistical analysis of structural breaks in discrete valued time series processes." Thesis, University of Liverpool, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.539614.

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Mohammed, Zakariya Mohammed Salih. "Analysis and Estimation of Customer Survival Time in Subscription-based Businesses." Thesis, University of the Western Cape, 2008. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_1022_1266526403.

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<p>The aim of this study is to illustrate, adapt and develop methods of survival analysis in analysing and estimating customer survival time in subscription-based businesses. Two particular objectives are studied. The rst objective is to redene the existing survival analysis techniques in business terms and to discuss their uses in order to understand various issues related to the customer-rm relationship.</p>

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37

Göeggel, Mathias Christian. "Closed-form solutions to discrete-time portfolio optimization problems." Diss., Rolla, Mo. : Missouri University of Science and Technology, 2010. http://scholarsmine.mst.edu/thesis/pdf/Goeggel_09007dcc807a9b0b.pdf.

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Thesis (M.S.)--Missouri University of Science and Technology, 2010.<br>Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed June 7, 2010) Includes bibliographical references (p. 75).

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Haddleton, Steven W. "Steady-state performance of discrete linear time-invariant systems /." Online version of thesis, 1994. http://hdl.handle.net/1850/11795.

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Li, Jiahui, and 黎嘉慧. "On discrete-time risk models with dependence based on integer-valued time series processes." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B48521875.

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In the actuarial literature, dependence structures in risk models have been extensively studied. The main theme of this thesis is to investigate some discrete-time risk models with claim numbers modeled by integer-valued time series processes. The first model is a common shock risk model with temporal dependence between the claim numbers in each individual class of business. Specifically the Poisson MA(1) process and Poisson AR(1) process are considered for the temporal dependence. To study the ruin probability, the equations associated with the adjustment coefficients are derived. Comparisons are also made to assess the impact of the dependence structures on the ruin probability. Another model involving both the correlated classes of business and the time series approach is then studied. Thinning dependence structure is adopted to model the dependence among classes of business. The Poisson MA(1) and Poisson AR(1) processes are used to describe the claim-number processes. Adjustment coefficients and ruin probabilities are examined. Finally a discrete-time risk model with the claim number following a Poisson ARCH process is proposed. In this model, the mean of the current claim number depends on the previous observations. Within this framework, the equation for finding the adjustment coefficient is derived. Numerical studies are also carried out to examine the effect of the Poisson ARCH dependence structure on several risk measures including ruin probability, Value at Risk, and conditional tail expectation.<br>published_or_final_version<br>Statistics and Actuarial Science<br>Master<br>Master of Philosophy

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Fan, Juanjuan. "Dependency estimation over a finite bivariate failure time region /." Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/9548.

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Barth, Eric J. "Approximating infinite horizon discrete-time optimal control using CMAC networks." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/19464.

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42

Freeland, R. Keith. "Statistical analysis of discrete time series with application to the analysis of workers' compensation claims data." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq27144.pdf.

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43

Özden, Eda [Verfasser], and K. [Akademischer Betreuer] Furmans. "Discrete Time Analysis of Consolidated Transport Processes / Eda Özden. Betreuer: K. Furmans." Karlsruhe : KIT-Bibliothek, 2012. http://d-nb.info/1019361859/34.

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44

Singh, Jayant. "Optimization Problems Arising in Stability Analysis of Discrete Time Recurrent Neural Networks." Diss., North Dakota State University, 2016. http://hdl.handle.net/10365/25537.

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We consider the method of Reduction of Dissipativity Domain to prove global Lyapunov stability of Discrete Time Recurrent Neural Networks. The standard and advanced criteria for Absolute Stability of these essentially nonlinear systems produce rather weak results. The method mentioned above is proved to be more powerful. It involves a multi-step procedure with maximization of special nonconvex functions over polytopes on every step. We derive conditions which guarantee an existence of at most one point of local maximum for such functions over every hyperplane. This nontrivial result is valid for wide range of neuron transfer functions.

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45

Navarro, Ruiz Juan Miguel. "Discrete-time modelling of diffusion processes for room acoustics simulation and analysis." Doctoral thesis, Universitat Politècnica de València, 2012. http://hdl.handle.net/10251/14861.

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Esta tesis está centrada en el modelado de la acústica de salas en espacios cerrados mediante el uso de una ecuación de transferencia radiativa y una ecuación de difusión En este trabajo se investiga cómo a través de estos modelos teóricos se pueden simular el campo sonoro en espacios complejos. Recientemente, el modelo de la ecuación de fusión ha sido prppuesto para ser utilizado en el modelado de la acústica de salas con superficies que reflejan el sonido de forma totalmente difusa. Este enfoque del uso de la ecuación de la disusión de sido intensamente investigado en los últimos años, ya que proporciona una alta eficiencia y flexibilidad para simular las distribuciones del campo sonoro en diferentes tipos de salas; sin embargo, sólo se han realizado unas pocas investigaciones con el objetivo de indagar sobre la precisión y las limitaciones de este método alternativo. Por lo tanto, en primer lugar se presenta un modelo basado en la ecuación de transferencia por radiación siendo meta principal el unificar una amplia gama de métodos geométricos de modelado de acústica de salas. Además, esta tesis está especialmente dedicada a establecer las bases y suposiciones que permitan obtener un modelo de difusión acústica como particularización del modelo de transferencia radiativa con el objetivo de conseguir una descripción clara y adecuada de sus ventajas y limitaciones desde el punto de vista teórico. Este trabajo permite enlazar directamente al modelo de la ecuación de difusión con el grupo de métodos de la acústica geométrica reforzando sus características y permitiendo una adecuada comparación con estos métodos ampliamente reconocidos. Una vez realizado este análisis teórico, esta tesis también se dedica a cuestiones relativas a la implementación numérica del modelo acústico de la ecuación de difusión . En este trabajo, se modela el campo sonoro a través de esquemas en diferencias finitas. Los resultados de este estudio proporcionan soluciones simples y practicas que muestran unos requerimientos computacionales bajos tanto de consumo de memoria como de tiempo.<br>Navarro Ruiz, JM. (2012). Discrete-time modelling of diffusion processes for room acoustics simulation and analysis [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/14861<br>Palancia

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46

Lim, Hee-Jeong. "Statistical analysis of interval-censored and truncated survival data /." free to MU campus, to others for purchase, 2001. http://wwwlib.umi.com/cr/mo/fullcit?p3025635.

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47

El-Shafey, Mohamed Hassan. "Linear continuous-time system identification and state observer design by modal analysis." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/28666.

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A new approach to the identification problem of linear continuous-time time-invariant systems from input-output measurements is presented. Both parametric and nonparametric system models are considered. The new approach is based on the use of continuous-time functions, the modal functions, defined in terms of the system output, the output derivatives and the state variables under the assumption that the order n of the observable system is known a priori. The modal functions are obtained by linear filtering operations of the system output, the output derivatives and the state variables so that the modal functions are independent of the system instantaneous state. In this case, the modal functions are linear functions of the input exponential modes, and they contain none of the system exponential modes unlike the system general response which contains modes from both the system and the input. The filters parameters, the modal parameters are estimated using linear regression techniques. The modal functions and the modal parameters of the output and its derivatives are used to identify parametric input-output and state models of the system. The coefficients of the system characteristic polynomial are obtained by solving n algebraic equations formed from the estimates of the modal parameters. Estimates of the parameters associated with the system zeros are obtained by solving another set of linear algebraic equation. The system frequency response and step response are estimated using the output modal function. The impulse response is obtained by filtering the estimated step response using the output first derivative modal parameters. A new method is presented to obtain the system poles as the eigenvalues of a data matrix formed from the system free response. The coefficients of the system characteristic polynomial are obtained from the data matrix through a simple recursive equation. This method has some important advantages over the well known Prony's method. The state modal functions are used to obtain a minimum-time observer that gives the continuous-time system state as a direct function of input-output samples in n sampling intervals.<br>Applied Science, Faculty of<br>Electrical and Computer Engineering, Department of<br>Graduate

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48

Schleyer, Marc [Verfasser]. "Discrete time analysis of batch processes in material flow systems / von Marc Schleyer." Karlsruhe : Univ.-Verl. Karlsruhe, 2007. http://d-nb.info/985217022/34.

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49

Kruggel-Emden, Harald [Verfasser]. "Analysis and Improvement of the Time-Driven Discrete Element Method / Harald Kruggel-Emden." Aachen : Shaker, 2008. http://d-nb.info/1164341219/34.

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50

Wilson, Bev Song Yan. "Scale effects and the determinants of parcel subdivision a discrete-time hazard analysis /." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2009. http://dc.lib.unc.edu/u?/etd,2252.

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Thesis (Ph. D.)--University of North Carolina at Chapel Hill, 2009.<br>Title from electronic title page (viewed Jun. 26, 2009). "... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of City and Regional Planning." Discipline: City and Regional Planning; Department/School: City and Regional Planning.

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