Дисертації з теми "Cox Proportional Hazard Regression Model"
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Crumer, Angela Maria. "Comparison between Weibull and Cox proportional hazards models." Kansas State University, 2011. http://hdl.handle.net/2097/8787.
Повний текст джерелаDepartment of Statistics
James J. Higgins
The time for an event to take place in an individual is called a survival time. Examples include the time that an individual survives after being diagnosed with a terminal illness or the time that an electronic component functions before failing. A popular parametric model for this type of data is the Weibull model, which is a flexible model that allows for the inclusion of covariates of the survival times. If distributional assumptions are not met or cannot be verified, researchers may turn to the semi-parametric Cox proportional hazards model. This model also allows for the inclusion of covariates of survival times but with less restrictive assumptions. This report compares estimates of the slope of the covariate in the proportional hazards model using the parametric Weibull model and the semi-parametric Cox proportional hazards model to estimate the slope. Properties of these models are discussed in Chapter 1. Numerical examples and a comparison of the mean square errors of the estimates of the slope of the covariate for various sample sizes and for uncensored and censored data are discussed in Chapter 2. When the shape parameter is known, the Weibull model far out performs the Cox proportional hazards model, but when the shape parameter is unknown, the Cox proportional hazards model and the Weibull model give comparable results.
Sasieni, Peter D. "Beyond the Cox model : extensions of the model and alternative estimators /." Thesis, Connect to this title online; UW restricted, 1989. http://hdl.handle.net/1773/9556.
Повний текст джерелаLindberg, Erik. "A study of the effect of inbreeding in Skellefteå during the 19th century : Using Cox Proportional hazard model to analyze lifespans and Poisson/Negative Binomial regression to analyze fertility." Thesis, Umeå universitet, Statistik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-122687.
Повний текст джерелаCalsavara, Vinícius Fernando. "Estimação de efeitos variantes no tempo em modelos tipo Cox via bases de Fourier e ondaletas Haar." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/45/45133/tde-26082015-140547/.
Повний текст джерелаThe semiparametric Cox model is often considered when modeling survival data. It is very flexible, allowing for the evaluation of covariates effects. One of its main advantages is the easy of interpretation, as long as the rate of the hazards for two individuals does not vary over time. However, this proportionality of the hazards may not be true in some practical situations and, in this case, an approach not relying on such assumption is needed. In this thesis we propose a Cox-type model that allows for time-varying covariate effects, for which the baseline hazard is based on Fourier series and wavelets on a time-frequency representation. We derive a prediction method for the survival of future patients with any specific set of covariates. Simulations and an application to a real data set suggest that our method may be a valuable tool to model data in practical situations where covariate effects vary over time. Through these studies, we make comparisons between the two approaches proposed here and comparisons with other already known in the literature, where we verify satisfactory results.
Thapa, Ram. "Modeling Mortality of Loblolly Pine Plantations." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/46726.
Повний текст джерелаPh. D.
Sauls, Beverly J. "Relative Survival of Gags Mycteroperca microlepis Released Within a Recreational Hook-and-Line Fishery: Application of the Cox Regression Model to Control for Heterogeneity in a Large-Scale Mark-Recapture Study." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4940.
Повний текст джерелаGwaze, Arnold Rumosa. "A cox proportional hazard model for mid-point imputed interval censored data." Thesis, University of Fort Hare, 2011. http://hdl.handle.net/10353/385.
Повний текст джерелаSandström, Caroline, and Karl Norling. "Female longevity : A survival analysis on 19th century women using the Cox Proportional Hazard model." Thesis, Umeå universitet, Statistiska institutionen, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-49700.
Повний текст джерелаMinya, Kristoffer. "Överlevnadsanalys i tjänsteverksamhet : Tidspåverkan i överklagandeprocessen på Migrationsverket." Thesis, Linköpings universitet, Statistik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-110428.
Повний текст джерелаThe Swedish Migration Board is an agency that review applications from individuals who wish to seek shelter, have citizenship, study or want to work in Sweden. In recent time there has been a large increase in applications and the time for which a decision is made has increased. Each type of application (such as citizenship) is a process consisting of several stages. How the decision is going through these steps is called flow. The Swedish Migration Board would therefore like to increase their flow efficiency. When the decision is made and the person has take part of it but is not satisfied, he can appeal. This is one of the most complex processes at the Board. The aim is to analyze how long this process will take and what steps in the process affects the time. One step (which was later found to have a significant effect on time) is opinions. This is when the court requests information on what the person is appealing has to say about why he is appealing. To analyze this, two methods were relevant, accelerated failure time (AFT) and the multi-state models (MSM). One can predict time to event (AFT), the other to analyze the effect of time-manipulation (MSM) in the flow. Opinions early in the process is crucial to how quickly an appeal get judgment while the number of opinions increases the time enormously. There are other factors that affect the time but not so much as opinions. The flow efficiency can be increased by taking time to write an informative opinion which allows the court need not to ask for more opinions.
Sposito, Ítalo Beltrão. "Continuidade e mudança na política externa dos estados latino-americanos (1945-2008)." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/101/101131/tde-28032016-141512/.
Повний текст джерелаThis thesis object is the foreign policy restructuring (FPR) - conceptualized as the most radical, encompassing, and fast changes in foreign policy. To analyze this phenomenon, there will be sought the main conjuncture conditions that might enhance the chances of this event occurrence. These conditions are related to the Policy Window concept, that represents a period during which the political inertia is disrupted and decision makers have the circumstances to undertake a FPR process. Objective: find and outline the conjectural conditions and variables that increase the chances of occurrence of a FPR. Methods: it will be used qualitative and quantitative methodological tools. In the second chapter, a survival model (Cox Proportional Hazard Model) analyses the effect variables related to the Policy Window concept over the risks of happening a FPR, defined as the most extreme changes of behavior in United Nations General Assembly roll-call votes. In the third chapter, a historical qualitative analysis is undertaken focusing exclusively on the most radical cases of FPR to develop explanatory typologies in order to identify causal conjunctures and common patters that lead to the outcome. Results: we identified that regime and political leader changes, in the national context, and military interventions by foreign powers enhance the risks of FPR occurrence; additionally, high political polarization combined with regime change, political crisis with international forces involvement, processes of international isolation with economic sanctions enforcement, and economic crises with political actors questioning the current economic model might be combined, configuring causal paths to a FPR. Conclusion: despite the importance of main political actors interest in implementing a FPR process, we identified that specific conjunctures and events raise the risks of a positive outcome.
Belcon, Michael C. "Determinants and Disparities of Survival in Triple-Negative Breast Cancer Patients: A Population-Based Retrospective Longitudinal Cohort Design Utilizing the Cox Proportional Hazard Analytical Model." FIU Digital Commons, 2015. http://digitalcommons.fiu.edu/etd/2311.
Повний текст джерелаYuan, Xingchen. "Survival Model and Estimation for Lung Cancer Patients." Digital Commons @ East Tennessee State University, 2005. https://dc.etsu.edu/etd/1002.
Повний текст джерелаCong, Chunling. "Statistical Analysis and Modeling of Breast Cancer and Lung Cancer." Scholar Commons, 2010. http://scholarcommons.usf.edu/etd/3563.
Повний текст джерелаTran, Xuan Quang. "Les modèles de régression dynamique et leurs applications en analyse de survie et fiabilité." Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0147/document.
Повний текст джерелаThis thesis was designed to explore the dynamic regression models, assessing the sta-tistical inference for the survival and reliability data analysis. These dynamic regressionmodels that we have been considered including the parametric proportional hazards andaccelerated failure time models contain the possibly time-dependent covariates. We dis-cussed the following problems in this thesis.At first, we presented a generalized chi-squared test statisticsY2nthat is a convenient tofit the survival and reliability data analysis in presence of three cases: complete, censoredand censored with covariates. We described in detail the theory and the mechanism to usedofY2ntest statistic in the survival and reliability data analysis. Next, we considered theflexible parametric models, evaluating the statistical significance of them by usingY2nandlog-likelihood test statistics. These parametric models include the accelerated failure time(AFT) and a proportional hazards (PH) models based on the Hypertabastic distribution.These two models are proposed to investigate the distribution of the survival and reliabilitydata in comparison with some other parametric models. The simulation studies were de-signed, to demonstrate the asymptotically normally distributed of the maximum likelihood estimators of Hypertabastic’s parameter, to validate of the asymptotically property of Y2n test statistic for Hypertabastic distribution when the right censoring probability equal 0% and 20%.n the last chapter, we applied those two parametric models above to three scenes ofthe real-life data. The first one was done the data set given by Freireich et al. on thecomparison of two treatment groups with additional information about log white blood cellcount, to test the ability of a therapy to prolong the remission times of the acute leukemiapatients. It showed that Hypertabastic AFT model is an accurate model for this dataset.The second one was done on the brain tumour study with malignant glioma patients, givenby Sauerbrei & Schumacher. It showed that the best model is Hypertabastic PH onadding five significance covariates. The third application was done on the data set given by Semenova & Bitukov on the survival times of the multiple myeloma patients. We did not propose an exactly model for this dataset. Because of that was an existing oneintersection of survival times. We, therefore, suggest fitting other dynamic model as SimpleCross-Effect model for this dataset
Turk, Ana. "Warranty claims analysis for household appliances produced by ASKO Appliances AB." Thesis, Linköpings universitet, Statistik, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-96955.
Повний текст джерелаFrazão, Italo Marcus da Mota. "Modelos com sobreviventes de longa duração paramétricos e semi-paramétricos aplicados a um ensaio clínico aleatorizado." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/11/11134/tde-13032013-093628/.
Повний текст джерелаSeveral models have been proposed in the literature with the aim of analyzing survival data when the population under study is assumed to be a mixture of susceptible (at risk) and not susceptible individuals to a specific event of interest. Such models are usually called long-term survivors models or cure rate models. In this work, several of these models (under both parametric and semi-parametric approaches) were considered to analyze the data from a randomized clinical trial conducted in order to compare three therapeutic strategies (surgery, angioplasty and medicine) used in the treatment of patients with multivessel coronary artery disease. For all models the logit and complementary log-log link functions were used to model the proportion of long-term survivors (not susceptible individuals). In regards to the survival function of the susceptible individuals, the Weibull and Cox models were used. Covariates were considered both in the proportion of longterm survivors and in the survival function of the susceptible individuals. Overall, the models considered were suitable for analyzing the data from the randomized clinical trial indicating surgery as the most effective therapeutic strategy. They also indicated that the covariates age, hypertension and diabetes mellitus exhibit influence on the occurrence of cardiac death, but not on the time to the occurrence of this death in susceptible patients.
Holcman, Marcia Moreira. "Avaliação do efeito das perdas de seguimento nas análises feitas pelo estimador produto - limite de Kaplan - Meier e pelo modelo de riscos proporcionais de Cox." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/6/6132/tde-08032007-100521/.
Повний текст джерелаIntroduction: The Kaplan Meier product limit estimator (KM) and the Cox proportional hazard (HR) model are the most used tools in survival analysis. These two methods have the key assumption that censoring must be independent from the survival time. Objective: To analyze the consequences of loss to follow up in these two methods. Methods: The study has utilized the data of the Cancer Registry of the patients of Hospital do Cancer in São Paulo of 1994. The informative censure was simulated transforming the death by 5 to 50% into alive. Besides 5 to 50% was spared at random simulating the non-informative censoring. The survival probability and was calculated to the first, third and fifth year of follow up. All the estimated probabilities and HRs were compared with the results of the original data. Results: Patients with greater scholars, lower stages and admitted by health plans or private had more losses to follow up. The maximum proportion of accepted loss to follow up is 10% to 15% when using the KM estimator, and the HR are less affected by the loss to follow-up and one can afford having 20% of it. When the losses were non informative there were no differences between the original probabilities. Conclusions: The possibility of over or under estimated probability must be analyzed in the presence of the losses to follow- up when using the KM and HR in survival analyses.
El, Nagar Ayman Gamal Fawzy. "Genetic analysis of longevity in specialized lines of rabbits." Doctoral thesis, Universitat Politècnica de València, 2015. http://hdl.handle.net/10251/52390.
Повний текст джерела[ES] El objetivo global de la presente tesis fue estudiar la longevidad funcional en cinco líneas españolas de conejos (A, V, H y LP), el carácter se definió como la longitud de la vida productiva. En el Capítulo 3, dirigido a comprobar la heterogeneidad genética de la longevidad entre las 5 líneas, se estimaron las varianzas aditivas y sus correspondientes heredabilidades efectivas. Y además se evaluó la importancia del orden de la palpación positiva (OPP), el estado fisiológico (PS) y el número de gazapos nacidos vivos (NBA) sobre el determinismo genético de la longevidad. Para ello se utilizaron 4 modelos de Cox de riesgos proporcionales; el primer modelo (Modelo 1) incluyó todos los factores anteriores, además del efecto del año-estación, el efecto de la consanguinidad y, finalmente, el valor aditivo de los animales como efecto aleatorio. Los otros tres modelos fueron igual que el Modelo 1 pero excluyendo OPP (Modelo 2), o PS (Modelo 3), o NBA (Modelo 4). Los datos de longevidad estaban referidos a 15,670 conejas y tuvieron una tasa de censura de 35.6%. La genealogía completa involucró a 19,405 animales. Las estimas de heredabilidad efectiva para la longevidad en las 5 líneas fueron bajas y variaron de 0.02±0.01 a 0.14±0.09. A pesar de la gran variación de las estimas puntuales de heredabilidad, los correspondientes intervalos HPD95% siempre se solaparon y por lo tanto la hipótesis de que todas las líneas tengan la misma heredabilidad no pudo descartase. Se observó que la exclusión de PS incrementó la varianza aditiva aproximadamente, en un 51, 39, 38, 83 y 75% en las líneas A, V, H, LP y R, respectivamente. El riesgo de muerte o eliminación disminuía a medida que avanzaba el OPP, observándose el riesgo más alto durante los primeros dos partos, partos en los que las conejas todavía están creciendo lo que sería un factor de riesgo importante. El nivel No-Gestante-No-Lactante de PS tuvo el mayor riesgo. Este nivel se interpreta como indicador de baja fertilidad y/o problemas de salud de la coneja. Las conejas que tenían cero NBA tuvieron el mayor riesgo de muerte o eliminación, aunque para el resto de niveles de NBA se apreció una disminución del riesgo a medida que aumenta la prolificidad. En el capítulo 4, se estimaron las correlaciones genéticas y ambientales entre la longevidad y dos caracteres de prolificidad [número de gazapos nacidos vivos (NBA) y el número de destetados (NW)]. El fichero de datos incluyó 58,329 partos y 57,927 destetes. También se estimaron las correlaciones entre longevidad y el porcentaje de días que la coneja pasó en los diferentes estados fisiológicos con respecto a la totalidad de su vida productiva. La única línea para la que se puede decir que la correlación genética entre NBA o NW y el riesgo fue significativamente diferente de cero fue la línea LP. Hubo evidencias de correlaciones genéticas no despreciables entre la longevidad y el porcentaje de días que la hembra pasó en cada estado fisiológico los dos caracteres. En el capítulo 5 se compararon las longevidades medias de las 5 líneas en su fundación y en períodos de tiempo determinados. La comparación de las líneas en el origen, utilizó todos los datos y un modelo genético (CM) que incluía los valores aditivos de los animales. Para la comparación en tiempos fijos se utilizó el mismo modelo, pero excluyendo los efectos aditivos del modelo de análisis (IM), utilizando sólo los datos correspondientes a cada período, por lo que las diferencias entre las líneas incluían los cambios debidos a la selección. Las líneas V, H y LP mostraron una superioridad sustancial sobre las líneas A y R. Los riesgos relativos máximos se observaron entre las líneas LP y R (0.239), y entre LP y A (0.317). Con respecto a las comparaciones en tiempos fijos, el patrón de las diferencias entre la línea de A y las otras líneas fue similar a los observados en la fundación.
[CAT] L'objectiu global de la present tesi va ser estudiar la longevitat funcional en cinc línies espanyoles de conills (A, V, H i LP), el caràcter es va definir com la longitud de la vida productiva. Al Capítol 3, dirigit a comprovar l'heterogeneïtat genètica de la longevitat entre les 5 línies, es van estimar les variàncies additives i les seues corresponents heretabilitats efectives. A més a més, es va avaluar la importància de factors dependents del temps, com l'orde de la palpació positiva (OPP) , l'estat fisiològic (PS) i el nombre de llorigons nascuts vius (NBA) sobre el determinisme genètic de la longevitat. Per a això es van utilitzar 4 models de Cox de riscos proporcionals; el primer model (Model 1) va incloure tots els factors anteriorment assenyalats, a més de l'efecte de l'any-estació, l'efecte de la consanguinitat i, finalment, el valor additiu dels animals com a efecte aleatori. Els altres tres models van ser igual que el Model 1 però excloent l'OPP (Model 2) , o PS (Model 3) , o NBA (Model 4) . Les dades de longevitat estaven referides a 15,670 conilles i van tindre una taxa de censura de 35.6%. La genealogia completa va involucrar a 19,405 animals. Les estimes d'heretabilitat efectiva (Model 1) per a la longevitat en les 5 línies van ser baixes i van variar de 0.02±0.01 a 0.14±0.09. A pesar de la gran variació de les estimes puntuals d'heretabilitat, els corresponents intervals HPD95% sempre es van solapar i per tant la hipòtesi que totes les línies tinguen la mateixa heretabilitat no va poder descartar-se. Es va observar que l'exclusió de PS va incrementar la variància additiva, aproximadament, en un 51, 39, 38, 83 i 75% en les línies A, V, H, LP i R, respectivament. El risc de mort o eliminació disminuïa a mesura que avançava l'OPP, observant-se el risc més alt durant els primers dos parts, en què les conilles encara estan creixent el que seria un factor de risc important. El nivell No-Gestant-No-Lactant de PS va tindre el major risc en comparació amb els altres nivells. Les conilles que tenien zero NBA van tindre el major risc de mort o eliminació, encara que per a la resta de nivells de NBA es va apreciar una disminució del risc a mesura que augmentà la prolificitat. Al Capítol 4, es van estimar les correlacions genètiques i ambientals entre la longevitat i dos caràcters de prolificitat [nombre de llorigons nascuts vius (NBA) i el nombre de deslletats (NW)]. El fitxer de dades va incloure 58,329 parts i 57,927 deslletaments. L'única línia per a la que es pot dir que la correlació genètica entre NBA o NW i el risc va ser significativament diferent de zero va ser la línia LP. Evidències de correlacions genètiques no menyspreables entre longevitat i els percentatge de dies que la femella va passar en cada estat fisiològic. Al Capítol 5 es compararen les longevitats mitges de les 5 línies en la seua fundació i en períodes de temps determinats. Per a la comparació de les línies a l'origen, es van utilitzar totes les dades i un model genètic (CM) que incloïa els valors additius dels animals, per la qual cosa es va considerar l'efecte de la selecció a partir de la fundació. En la comparació en temps fixos se va utilitzar el mateix model que en l'anterior, però excloent els efectes additius del model d'anàlisi (IM), utilitzant només les dades corresponents a cada període, per la qual cosa les diferències entre les línies incloïen els canvis deguts a la selecció. Les línies V, H i LP van mostrar una superioritat substancial sobre les línies A i R. Els riscos relatius màxims es van observar entre les línies LP i R (0.239), i entre LP i A (0.317). Respecte a les comparacions en temps fixos, el patró de les diferències entre la línia de A i les altres línies va ser semblant als observats en la fundació.
El Nagar, AGF. (2015). Genetic analysis of longevity in specialized lines of rabbits [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/52390
TESIS
Lee, Kyeong Eun. "Bayesian models for DNA microarray data analysis." Diss., Texas A&M University, 2005. http://hdl.handle.net/1969.1/2465.
Повний текст джерелаLi, Qiuju. "Statistical inference for joint modelling of longitudinal and survival data." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/statistical-inference-for-joint-modelling-of-longitudinal-and-survival-data(65e644f3-d26f-47c0-bbe1-a51d01ddc1b9).html.
Повний текст джерелаHoglin, Phillip J. "Survival analysis and accession optimization of prior enlisted United States Marine Corps officers." Thesis, Monterey, California. Naval Postgraduate School, 2004. http://hdl.handle.net/10945/1673.
Повний текст джерелаThe purpose of this thesis is to firstly analyze the determinants on the survival of United States Marine Corps Officers, and secondly, to develop the methodology to optimize the accessions of prior and non-prior enlisted officers. Using data from the Marine Corps Officer Accession Career file (MCCOAC), the Cox Proportional Hazards Model is used to estimate the effects of officer characteristics on their survival as a commissioned officer in the USMC. A Markov model for career transition is combined with fiscal data to determine the optimum number of prior and non-prior enlisted officers under the constraints of force structure and budget. The findings indicate that prior enlisted officers have a better survival rate than their non-prior enlisted counterparts. Additionally, officers who are married, commissioned through MECEP, graduate in the top third of their TBS class, and are assigned to a combat support MOS have a better survival rate than officers who are unmarried, commissioned through USNA, graduate in the middle third of their TBS class, and are assigned to either combat or combat service support MOS. The findings also indicate that the optimum number of prior enlisted officer accessions may be considerably lower than recent trends and may differ across MOS. Based on the findings; it is recommended that prior enlisted officer accession figures be reviewed.
Major, Australian Army
Karimi, Maryam. "Modélisation conjointe de trajectoire socioprofessionnelle individuelle et de la survie globale ou spécifique." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS120/document.
Повний текст джерелаBeing in low socioeconomic position is associated with increased mortality risk from various causes of death. Previous studies have already shown the importance of considering different dimensions of socioeconomic trajectories across the life-course. Analyses of professional trajectories constitute a crucial step in order to better understand the association between socio-economic position and mortality. The main challenge in measuring this association is then to decompose the respectiveshare of these factors in explaining the survival level of individuals. The complexity lies in the bidirectional causality underlying the observed associations:Are mortality differentials due to differences in the initial health conditions that are jointly influencing employment status and mortality, or the professional trajectory influences directly health conditions and then mortality?Standard methods do not consider the interdependence of changes in occupational status and the bidirectional causal effect underlying the observed association and that leads to substantial bias in estimating the causal link between professional trajectory and mortality. Therefore, it is necessary to propose statistical methods that consider simultaneously repeated measurements (careers) and survivalvariables. This study was motivated by the Cosmop-DADS database, which is a sample of the French salaried population.The first aim of this dissertation was to consider the whole professional trajectories and an accurate occupational classification, instead of using limitednumber of stages during life course and a simple occupational classification that has been considered previously. For this purpose, we defined time-dependent variables to capture different life course dimensions, namely critical period, accumulation model and social mobility model, and we highlighted the association between professional trajectories and cause-specific mortality using the definedvariables in a Cox proportional hazards model.The second aim was to incorporate the employment episodes in a longitudinal sub-model within the joint model framework to reduce the bias resulting from the inclusion of internal time-dependent covariates in the Cox model. We proposed a joint model for longitudinal nominal outcomes and competing risks data in a likelihood-based approach. In addition, we proposed an approach mimicking meta-analysis to address the calculation problems in joint models and large datasets, by extracting independent stratified samples from the large dataset, applying the joint model on each sample and then combining the results. In the same objective, that is fitting joint model on large-scale data, we propose a procedure based on the appeal of the Poisson regression model. This approach consist of finding representativetrajectories by means of clustering methods and then applying the joint model on these representative trajectories
Persson, Daniel, and Johannes Ahlström. "Går det att prediktera konkurs i svenska aktiebolag? : En kvantitativ studie om hur finansiella nyckeltal kan användas vid konkursprediktion." Thesis, Linköpings universitet, Företagsekonomi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-119867.
Повний текст джерелаFrom the early 1900s, banks and lending institutions have used financial ratios as an aid in the assessment and quantification of credit risk. For today's investors the economic environment is far more complicated than 40 years ago when the technology and computerization opened up the world's markets. Credit risk assessment today requires effective analysis of quantitative data and models that can predict risks with good accuracy. During the second half of the 20th century there was a rapid development of the tools used for bankruptcy prediction. We moved from simple univariate models to complex data mining models with thousands of observations. This study investigates if it’s possible to predict bankruptcy in Swedish limited companies and which variables contain information relevant for this cause. The methods used in the study are discriminant analysis, logistic regression and survival analysis on 50 active and 50 failed companies. The results indicate accuracy between 67.5 % and 75 % depending on the choice of statistical method. Regardless of the selected statistical method used, it’s possible to classify companies as bankrupt two years before the bankruptcy occurs using financial ratios which measures profitability and solvency. Societal costs are reduced by better bankruptcy prediction using financial ratios which contribute to increasing the ability of companies to apply financial management with relevant key ratios in the form of stock , retained earnings , net income and operating income.
Liu, Chia-Chiung, and 劉佳峻. "A simulation study for cut points analysis in Logist regression and Cox proportional hazards model." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/yn3698.
Повний текст джерела國立中山大學
應用數學系研究所
107
In clinical practice, it is often necessary to segment the continuous variables for risk assessment, that is, to convert the continuous prognostic factors into categories to facilitate clinical judgment and interpretation. There are three problems to be solved in the study of estimating cut points. The first problem is to determine the optimal number of cut points. In the traditional methods, many of them have been developed to find one optimal cut point to categorize variables into two subgroup. However, in a lot of situations, finding more than one cut points is of interest. The second one is to find the location of optimal cut points. The last one is the statistical inferences after finding the optimal number and locations of cut points, including correcting the p-value, relative risks, powers, etc. In previous theses(Tsai, Y.H.(2018), and Chiu, Y.C.(2018)), they proposed a new approach in both the logistic and Cox regression models, combining the cross-validation and Monte Carlo methods(CVM), to find the optimal number and locations of cut points. However, in their theses, the proposed method was not compared with other methods. In this thesis, we conducted simulation studies to compare the proposed CVM with three other methods, including naive approach(without any correction,NA), split-sample approach(SS), and cross-validation approach(CV). We compares the performance between these four methods in estimating the number and location s of cut points, relative risks, and powers in both univariate and multivariate analysis and for different sample sizes.
Joy, Nathaniel Allen. "A Duration Analysis of Food Safety Recall Events in the United States: January, 2000 to October, 2009." Thesis, 2010. http://hdl.handle.net/1969.1/ETD-TAMU-2010-12-8826.
Повний текст джерелаHsiao, Han, and 蕭涵. "Analysis of high dimensional gene expression and mutation data in bladder cancer using Cox proportional hazards model and logistic regression via different penalizations." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/amf4n9.
Повний текст джерела國立中山大學
應用數學系研究所
106
Bladder cancer is one of the malignant diseases in urinary system. Its common symptoms include hematuria which could be seen through eyes or urine analysis. In order to understand the effect of gene expression and mutation data on subtypes and recurrent event in patients with bladder cancer, we downloaded data from The Cancer Genome Atlas (TCGA) and applied high-dimensional analysis such as LASSO, Ridge, Adaptive Lasso and Cox model to screen gene variables, compare the performance of different models and predict the hazard of each patients. Among the selected gene candidates, we found TP53 and ERBB3 have been published in quite a few papers, which could verify our method. Not only the list of genes could help the lab to perform further analysis but also it could screen out the potential patients in advance. On the other hand, we also wrote some functions to access and deal with gene database in R language, which could be used by other researchers in the future.
Martínez, Vargas Danae Mirel. "Régression de Cox avec partitions latentes issues du modèle de Potts." Thèse, 2019. http://hdl.handle.net/1866/22552.
Повний текст джерелаLiao, Yi-Nan, and 廖宜楠. "Event Per Variable in Cox Proportional Hazard Model." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/38265148402104684976.
Повний текст джерела國立陽明大學
公共衛生研究所
98
Abstract Background:Small number of events often occurred due to short follow-up times or not enough individuals being followed in clinical, epidemiological, or environment studies. It could seriously affect the accuracy and efficiency of the estimates of regression coefficient when using Cox proportional hazard model when event numbers are not enough. Previously studies have shown that the parameter estimates are valid when events per variable (EPV) are more than 10. However, these EPV related simulation studies which focus on Cox proportional hazard models only use methods that are appropriate for large sample. Objectives:To compare the accuracy and the efficiency of the parameter estimates of Cox models using different methods such as Partial likelihood method, Firth’s penalized likelihood method, and Bayesian methods. Methods:In the context of Cox proportional hazard model, this simulation study compared (1)different estimating methods of parameter, including Standard Cox method、Firth’s penalized likelihood method and Bayesian method. (2)different methods of calculating confidence intervals, including Wald-based method、profile likelihood methods, and Bayesian credible intervals. (3)different numbers of EPV. (4) categorical variables or and continuous variables, with collinearity or not, and (6)different methods of generating survival data. Results and Conclusions:For categorical variables, when EPV is less than or equal to 4, the accuracy and the efficiency of the parameter estimates by Firth’s method are better than those by standard Cox method. When EPV is greater than or equal to 10, Firth’s method performs as well as standard Cox method. For Continuous variables, the accuracy and the efficiency of Firth’s method and standard Cox method are similar. The estimate by Bayesian method is close to the pre-set prior distribution when EPV is small. As the EPV increases, the estimates approaches the true parameter.
Yu-Jheng, Su, and 蘇育正. "Adaptive model selection criterion:An application of Cox proportional hazard model." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/19790975378637992966.
Повний текст джерела東海大學
統計學系
99
The Cox proportional hazards model has been widely used to describe the relationship between survival information and covariates. For model selection Akaike information criterion (AIC) and Bayesian information criterion (BIC) are the most frequently used methods. However the two information criteria may generally perform differently under different circumstances, so that neither the AIC nor the BIC is superior in all cases. In practice, the underlying true model is unknown and model selection is only based on the specific selection criteria. Therefore, in this article, we propose a data driven method to choose the optimal penalty parameter based on a concept of generalized degrees of freedom, resulting in an approximately unbiased estimator of the Kullback-Leibler loss via a data perturbation technique. The effectiveness of the proposed method is justified by a simulation study. Finally, we illustrate the feasibility of this method by the Ger- man Breast Cancer Study Group’ s data set.
Tung, Feng-Cheng, and 董峰呈. "Mutual Fund’s Failure Prediction - Cox''s Proportional Hazard Model." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/26173602273714817022.
Повний текст джерела國立高雄第一科技大學
金融營運系碩士班
89
ABSTRACT This study applies Cox’s(1984) PHM(Proportional Hazard Model) to set up the pre-warning models for the failure of mutual fund. This study consists 40 mutual funds in Taiwan Stock Exchange during the period 1996-2000. This study uses twelve financial variables as endogenous factors of the mutual fund’s survival. This study expects the pre-warning models for the failure of mutual fund will be helpful for the investors to take some preventive action and reduce the risk of buying mutual fund. This study’s results indicate that the rate of three-monthly return , mutual fund beneficiary units are significant factors affecting the failure of mutual fund. This study also finds the possibility of financial distress is positively associated with the rates of three-monthly return and mutual fund beneficiary units. After the pre-warning models for the failure of mutual funds set up , the study selects 8 mutual funds in Taiwan Stock Exchange, based on the information available in February 2000, and predict the survival possibilities of mutual funds. This study finds the survival possibilities of Nation Wan-Tong and Chinese Wan-Bang fund after 30-month are lower in the 8 mutual funds . The study suggests that investors shall select the mutual funds which have higher rate of three-monthly return and more mutual fund beneficiary units.
Hsu, Wen Chu, and 許雯筑. "The Determinants of stock repurchse: cox proportional hazard model." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/66161651537784230258.
Повний текст джерела國立政治大學
國際經營與貿易研究所
96
In this study, we apply Cox proportional hazard model in recurrent event analysis, which usually used in medical and science studies, to analyze the determinants of the stock repurchase events of S&P 500 companies. We investigate three main incentives that companies conduct stock repurchase. The empirical results show that companies employ repurchase as a technique to alter capital structure. In addition, companies conduct stock repurchase to distribute excess capital. In contrast, there are little evidences to support signaling undervaluation.
Tsai, Tsungche, and 蔡宗哲. "Adaptive Model Selection Between Cox Proportional Hazard Model And Aalen Additive Model." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/87529691313741577966.
Повний текст джерела東海大學
統計學系
100
In medical studies, Cox proportional hazards model (Cox, 1972) is the most commonly used method to analyze the survivor function of patients when the right-censored survival data are accompany with covariates which are associated with patients’ physiology and conditions. However, the proportional hazards assumption is usually violated in practice. Therefore, the Aalen’s additive model (Aalen, 1989) is an alternative choice under consideration. In this model, the covariates act in an additive manner on an unknown baseline hazard rate. The unknown risk coefficients in the model are allowed to be functions of time so that the effect of a covariate may vary over time. However, the two models generally perform differently under different circumstances, so that neither the Cox model nor the Aalen model is superior in all cases. How to select between them has not been explored in the literature. Therefore, we proposed a data-driven method for making a selection based on a concept of generalized degrees of freedom, resulting in an approximately unbiased estimator of the Kullback-Leibler loss via a data perturbation technique. The effectiveness of the proposed method is justified by a simulation study and also is applied to two real data sets.
"Bootstrap distribution for testing a change in the cox proportional hazard model." 2000. http://library.cuhk.edu.hk/record=b5890302.
Повний текст джерелаThesis (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
Kao, Xin-ru, and 高欣如. "Discussion on Cox Proportional Hazards Assumption and Application of Extended Hazard Model." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/wh9svf.
Повний текст джерела國立中央大學
統計研究所
97
The Cox proportional hazards model has been widely used to describe the relationship between survival information and covariates. The validity to apply the Cox model for data is usually based on checking the proportional hazards assumption. It’s an interesting problem to investigate whether checking this assumption is sufficient as an evidence to fit data with the Cox model. On the other hand, when proportional hazards assumption fails, the Accelerated Failure Time (AFT) model is a popular alternative to the Cox model. However, when data include time-dependent covariates there are no convenient tools to check if AFT is appropriate for the data. An general class model termed “extended hazard model”, which contains the Cox and AFT models as its special case may be helpful to study the above problems. Because under the nested structure, we may test the fit of Cox and AFT models for data. Finally, we demonstrate the new model through a case study of Taiwanese HIV/AIDS cohort data.
Wu, Chi-ruei, and 吳啓瑞. "The study of mobile commerce and operational efficiency-an application of Cox proportional hazard model." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/49883964522804226652.
Повний текст джерела國立中央大學
企業管理研究所
100
As mobile communication technology evolves maturely, Banks introduce Mobile Banking services to customers. Banks can increase their competitiveness through unique convenience, immediacy and personalized services. Therefore, the purpose of this study is to investigate the relationship between the Mobile Banking service and the operational efficiency. This study adopts an only bank as a study case, and collects 30 records measured by quarter from 2004 1st quarter to 2011 1st quarter and 2012 1st quarter. First, the efficiency assessment of data was conducted by Data Envelopment Analysis and Slack-Based Measure to understand operational efficiency of target bank, and it analyzed the factors which improved bank operational efficiency with Cox proportional hazard model. The survey results indicate that the amount of Mobile Banking transactions had a positive relation and insignificant effect on the rate of immediacy improving efficiency. It demonstrates that Mobile baking under limitations of technology and transaction security fails to mitigate workload of physical banking channel; in other words, physical banking channel is not able to redistribute resources to more profitable business, therefore the bank''s operational efficiency improvement is not significant.
Otto, Simon James Garfield. "ANTIMICROBIAL RESISTANCE OF HUMAN CAMPYLOBACTER JEJUNI INFECTIONS FROM SASKATCHEWAN." Thesis, 2011. http://hdl.handle.net/10214/2658.
Повний текст джерелаSaskatchewan Disease Control Laboratory (Saskatchewan Ministry of Health); Laboratory for Foodborne Zoonoses (Public Health Agency of Canada); Centre for Foodborne, Environmental and Zoonotic Infectious Diseases (Public Health Agency of Canada); Ontario Veterinary College Blake Graham Fellowship
Guan-Lin, Huang, and 黃冠霖. "Apply Cox proportional hazard model to create customer loyalty index with case study of smartphone service industry." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/h4b7bd.
Повний текст джерела國立成功大學
工業與資訊管理學系碩博士班
101
The goal of the enterprise operation is to earn profit under limited resources. Customers are the source of the profit and loyal customers can bring stable income. Since the cost of finding new customers is much higher than retaining the existing customers, creating a customer loyalty index and then managing customer loyalty have become a major issue for business nowadays. In this study, we propose a customer loyalty index by Cox proportional hazards model. Our method integrates customer prognostic factors, consumer behavior, service quality, customer satisfaction, and switching costs into our model to evaluate the probability of loss of customers. Let the loss of customer as the event, we calculate hazard ratio for each customer respect to a reference point. Our method is applied to a case from the smartphone service industry. The results showed that mobile connection quality, the gap between expectations and reality, the customer re-patronage intentions, and the age of customer may affect events of loss of customers. Finally, according to hazards ratio to group and sort the customers, the management will have a better view of current distribution of customer loyalty.
Chen, Yi-Chun, and 陳怡君. "A study on merger & acquisition and duration in Taiwan airline markets: Application cox proportional hazard model." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/46828843673961945880.
Повний текст джерела長榮大學
企業管理研究所
96
In 1997, the domestic aviation transportation required volume reached its peak. However, after 1998, the prosperity of domestic aviation slide down all the way and transportation passenger plane with high cost became a heavy burden for aviation companies. In addition, Taiwan promote road construction and high speed railway in recent years and with the pressure of global recession, without doubt it is a great test for domestic aviation industry in terms of operation management.The research investigates the Domestic Airlines who have been manage the domestic route from 1996 to 2007.The research seeks to find out the key factors affecting the operation performance of airline companies by utilizing the Survival Analysis to examine the variables combination of the Frequency of Flight, Available Seat, Passengers Carried, Passenger Load Factor, Commercial course and Recreation course, the repeated course place of the high speed railway and domestic airlines and the course merges the performance of managing, per capita GDP. The result provides an important reference and basis for airline executives to improve deficiency and serves as a future operation direction. The result of study is found that available Seat, Commercial course, Course after merging, the repeated course place of the high speed railway and domestic airlines for influence domestic aviation industry factor, and find that merging will make the dangerous rate of course drop, look by managing the wise attitude, the result shows the course survival rate: Commercial attitude after merging is greater than Recreation type attitude after merging, Recreation type attitude after merging is greater than Commercial attitude not merged,Commercial attitude not merged is greater than Recreation type attitude not merged.
Tzu-HsuanLin and 林子暄. "Efficient estimation of the Cox proportional hazard model incorporating with the auxiliary subgroup information of incidence rate." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/kp962r.
Повний текст джерела國立成功大學
統計學系
107
Incidence rate for a disease have been wildly used in the field of medical research because of its clear physical and simple clinical interpretation. In this thesis, we propose an efficient estimation to incorporate with the auxiliary subgroup information of incidence rate information into the estimation of the Cox proportional hazard model. Comparing to the conventional models without incorporation of the available auxiliary information, utilizing the external information shows that the proposed method improves efficiency for the estimation of the regression parameters based on the maximum empirical likelihood method. In addition, simulation studies demonstrate that the proposed method gain in efficiency over the conventional approach.
Lee, Kuan-Ting, and 李冠霆. "Statistical analysis of censored endpoints under the Cox proportional hazard model for evaluation of targeted drug products under the enrichment design." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/01371322286722738530.
Повний текст джерела國立臺灣大學
農藝學研究所生物統計組
103
In traditional clinical trials, inclusion and exclusion criteria are considered based on some clinical endpoints, the genetic or genomic variability of the trial participants are not totally utilized in the criteria. After the Human Genome Project is completed, many molecules underlying disease can be identified, it is possible to develop a targeted molecular therapy. However, the accuracy of diagnostic devices for identification of such molecular targets is usually not perfect. Some patients with positive diagnosis result is actually might not have the specific molecular targets. As a result, the treatment effect may be underestimated in the patient population truly with the molecular target. In order to resolve this issue, we propose a method based on the mixture Cox’s proportional model for the k latent classes (Eng K.H. and Hanlon B.M., 2014) and under the enrichment design. We develop inferential procedures for the treatment effects of the targeted drug based on the censored endpoints in the patients truly with the molecular targets which also incorporates the inaccuracy of the diagnostic device for detection of the molecular targets on the inference of the treatment effects. We propose using the EM algorithm in conjunction with the bootstrap technique for estimation of hazard ratio and its variance. Though the simulation study, we empirically investigate the performance of the proposed methods and to compare with the current method. The numerical examples illustrate the proposed procedures.
Zavřelová, Adéla. "Semiparametrický model aditivního rizika." Master's thesis, 2020. http://www.nusl.cz/ntk/nusl-415878.
Повний текст джерелаChang, Chiayu, and 張家瑜. "Factors affecting the transition state of depression for the elderly in Taiwan - An application of the Cox proportional hazard model in competing risk." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/80316431886090881232.
Повний текст джерела東海大學
統計學系
100
Due to the rapid decline in fertility and increased longevity in recent years, Taiwan is experiencing a dramatic demographic transition in which the overall proportion of old people in the population is increasing. From many studies, it is evident that there is a steady increase in the incidence and prevalence of depression and related problems among the elderly population. Depression symptoms experienced in late life have serious implications for the health and functioning of older individuals. In addition, it might cause high mortality rates if the depression status of the elderly could not be improved. Thereby, one major task in the elderly population is to deal with the problem of depression. Since many aspects of mental health can be targeted for improvement in health care, the goal of this study is to discuss how the variables related to demographic, self-rated health, physical function and home condition determinants affect the transition state of depression for the elderly in Taiwan by employing Cox proportional hazard model in competing risks. The elderly data collected by the Bureau of Health Promotion of the Department of Health in Taiwan from 1989 to 2003, will be used to explore the variables related to depression symptom which is according to a complete set of depression scale (CES-D) data of the elderly. The old people who were 60 years old and over were first interviewed in 1989 and re-interviewed in 1993, 1996, 1999 and 2003. The Cox proportional hazard model in competing risks is used to explore whether some of the covariates of the factors e.g. demographic characteristics, home conditions, and health characteristics, are related to the three different types of transition about depression, such as transition, reverse transition and repeated transition. No matter the initial state of the elderly is with depression or without depression, the cumulative incidence functions and the Cox proportional hazard model in competing risk reveal that the home condition (economic status) and health characteristics (self-rated health and physical function) are strongly related to the depression of the elderly.
"An application of cox hazard model and CART model in analyzing the mortality data of elderly in Hong Kong." 2002. http://library.cuhk.edu.hk/record=b5891190.
Повний текст джерелаThesis (M.Phil.)--Chinese University of Hong Kong, 2002.
Includes bibliographical references (leaves 85-87).
Abstracts in English and Chinese.
Chapter 1 --- Introduction --- p.1
Chapter 1.1 --- Overview --- p.1
Chapter 1.1.1 --- Survival Analysis --- p.2
Chapter 1.1.2 --- Tree、-structured Statistical Method --- p.2
Chapter 1.1.3 --- Mortality Study --- p.3
Chapter 1.2 --- Motivation --- p.3
Chapter 1.3 --- Background Information --- p.4
Chapter 1.4 --- Data Content --- p.7
Chapter 1.5 --- Thesis Outline --- p.8
Chapter 2 --- Imputation and File Splitting --- p.10
Chapter 2.1 --- Imputation of Missing Values --- p.10
Chapter 2.1.1 --- Purpose of Imputation --- p.10
Chapter 2.1.2 --- Procedure of Hot Deck Imputation --- p.11
Chapter 2.1.3 --- List of Variables for Imputation --- p.12
Chapter 2.2 --- File Splitting --- p.14
Chapter 2.2.1 --- Splitting by Gender --- p.14
Chapter 2.3 --- Splitting for Validation Check --- p.1G
Chapter 3 --- Cox Hazard Model --- p.17
Chapter 3.1 --- Basic Idea --- p.17
Chapter 3.1.1 --- Survival Analysis --- p.17
Chapter 3.1.2 --- Survivor Function --- p.18
Chapter 3.1.3 --- Hazard Function --- p.18
Chapter 3.2 --- The Cox Proportional Hazards Model --- p.19
Chapter 3.2.1 --- Kaplan-Meier Estimate and Log-Rank Test --- p.20
Chapter 3.2.2 --- Hazard Ratio --- p.23
Chapter 3.2.3 --- Partial Likelihood --- p.24
Chapter 3.3 --- Extension of the Cox Proportional Hazards Model for Time-dependent Variables --- p.25
Chapter 3.3.1 --- Modification of the Cox's Model --- p.25
Chapter 3.4 --- Results of Model Fitting --- p.26
Chapter 3.4.1 --- Extract the Significant Covariates from the Models --- p.31
Chapter 3.5 --- Model Interpretation --- p.32
Chapter 4 --- CART --- p.37
Chapter 4.1 --- CART Procedure --- p.38
Chapter 4.2 --- Selection of the Splits --- p.39
Chapter 4.2.1 --- Goodness of Split --- p.39
Chapter 4.2.2 --- Type of Variables --- p.40
Chapter 4.2.3 --- Estimation --- p.40
Chapter 4.3 --- Pruning the Tree --- p.41
Chapter 4.3.1 --- Misclassification Cost --- p.42
Chapter 4.3.2 --- Class Assignment Rule --- p.44
Chapter 4.3.3 --- Minimal Cost Complexity Pruning --- p.44
Chapter 4.4 --- Cross Validation --- p.47
Chapter 4.4.1 --- V-fold Cross-validation --- p.47
Chapter 4.4.2 --- Selecting the right sized tree --- p.49
Chapter 4.5 --- Missing Value --- p.49
Chapter 4.6 --- Results of CART program --- p.51
Chapter 4.7 --- Model Interpretation --- p.53
Chapter 5 --- Model Prediction --- p.58
Chapter 5.1 --- Application to Test Sample --- p.58
Chapter 5.1.1 --- Fitting test sample to Cox's Model --- p.59
Chapter 5.1.2 --- Fitting test sample to CART model --- p.61
Chapter 5.2 --- Comparison of Model Prediction --- p.62
Chapter 5.2.1 --- Misclassification Rate --- p.62
Chapter 5.2.2 --- Misclassification Rate of Cox's model --- p.63
Chapter 5.2.3 --- Misclassification Rate of CART model --- p.64
Chapter 5.2.4 --- Prediction Result --- p.64
Chapter 6 --- Conclusion --- p.67
Chapter 6.1 --- Comparison of Results --- p.67
Chapter 6.2 --- Comparison of the Two Statistical Techniques --- p.68
Chapter 6.3 --- Limitation --- p.70
Appendix A: Coding Description for the Health Factors --- p.72
Appendix B: Log-rank Test --- p.75
Appendix C: Longitudinal Plot of Time Dependent Variables --- p.76
Appendix D: Hypothesis Testing of Suspected Covariates --- p.78
Appendix E: Terminal node report for both gender --- p.81
Appendix F: Calculation of Critical Values --- p.83
Appendix G: Distribution of Missing Value in Learning sample and Test Sample --- p.84
Bibliography --- p.85
Ejones, Francis. "Regional integration, trade duration and economic growth in the East African community: three empirical essays." Thesis, 2021. http://hdl.handle.net/1959.13/1421878.
Повний текст джерелаThe objective of this thesis is to investigate empirically the impact of regional trade agreements (RTAs) on trade, the duration of trade and economic growth in the East African Community (EAC) consisting of the republics of Kenya, Uganda, Burundi and Rwanda and the United Republic of Tanzania. Since the birth of the World Trade Organization (WTO) in 1995 and the establishment of the multilateral trading system, both developed and developing countries have initiated policies aimed at promoting North–South and South–South trade. Despite these efforts, the impact of multilateral trade agreements on trade and economic growth has been complex and is not well understood. The changing global marketplace—a consequence of external shocks and trade policy reforms across the developed and developing world—has led to increased regionalisation globally. Lack of scholarship on specific regional integration (RI) entities, such as the EAC, motivates the current research. In addition, as much as trade liberalisation in the EAC is commendable, there is strong evidence that trade reforms perform very poorly (Mishra, 2018; Rodrik, 1992). For instance, the EAC remains a marginal player in the global trade in goods (United Nations Conference on Trade & Development [UNCTAD], 2019). Further, the EAC’s level of intraregional trade is the lowest among all African RTAs, implying that the EAC does not perform as well as it does in the area of trade integration (Economic Commission for Africa [ECA], 2017). Such low levels of intraregional trade are still observed even though tremendous resources and strong political will continue to back progress towards implementation of the bloc (Vickers, 2017). Further, there are still discrepancies in the size and relative strength of the economies of the countries participating in the EAC, creating tensions over the perceived distribution of the benefits of RI (ECA, 2017). This thesis reports three empirical studies. The first examines the impact of RTAs on trade in the EAC. Utilising the traditional gravity model, this study extends the model to account for zero trade, endogeneity and heterogeneity. The model is estimated using the Poison pseudo-maximum likelihood estimator and a comprehensive panel dataset for the EAC for the period 1990–2017. The empirical results indicate, first, that although RTAs enhance trade in the EAC, the impact varies across the Common Market for Eastern and Southern Africa (COMESA), WTO markets and regional blocs. Second, although the RTAs enhance trade at the bloc level, results vary by country. Kenya, Rwanda and Uganda experience pure trade creation in the EAC market, though Uganda’s intra-bloc trade is below expectation. Third, the results indicate that there is asymmetry across products. For example, food trade leads to pure trade creation in the EAC and COMESA markets, but pure trade diversion in the WTO. Fourth, there is variation in the performance of products within countries, though the EAC RTA leads to trade creation for all products across the EAC. These empirical findings are robust to alternative model specifications. The second empirical study examines the impact of RTAs on the duration of trade in the EAC. The study specifies a variant of survival models and estimates the models using a comprehensive dataset for the period 1988–2015. The model is estimated using Kaplan–Meier, Cox proportional hazards and discrete time estimators. The empirical results show, first, that RTAs enhance the duration of exports in the EAC market, and inconsistently drive the duration of exports of the EAC in the COMESA market. However, RTAs do not lengthen the duration of EAC exports in the WTO trading market in aggregate. Second, the impact of RTAs on the duration of exports varies across countries: the EAC bloc leads to the persistence of exports in Tanzania and Uganda, while the COMESA bloc increases the duration of Kenya’s exports. Third, the impact of RTAs is heterogeneous across products. Fourth, the impact of RTAs on the duration of EAC exports is short lived with 50% of exports coming to an end within 2–3 years. Fifth, export hazards are quite high at the beginning of trading relationships but stabilise over time, albeit for only a few trade spells. That is, the key drivers of trade duration are gravity-like covariates, fixed trade cost variables and duration ‘type’ covariates. The third empirical study examines the impact of RTAs on economic growth in the EAC. The study specifies an endogenous growth model and estimates the model using feasible generalised least squares and panel corrected standard error estimators. The empirical results indicate, first, that RTAs and trade openness enhance economic growth in the EAC. Second, RTAs have impacts that are more significant for economic growth in the EAC than for trade openness measures. Third, the impact of trade liberalisation varies across regional markets. For instance, the EAC regional market has a more significant impact on economic growth than do plurilateral (COMESA) and multilateral (the WTO) trade agreements. Fourth, the impacts of RTAs on economic growth vary across countries in the EAC. These empirical results are robust to alternative model specifications. The thesis makes three major contributions that have important policy implications. The first draws from the empirical findings of Study 1, which provides new evidence that RTAs do have a positive effect on trade in the EAC and support third countries’ trade. However, the impacts of RTAs on trade vary across countries and product groupings. The policy implication is that there is a need to strengthen trade liberalisation within the EAC with a special focus on strengthening RTAs. Adopting holistic policies may not be appropriate because of their varying impacts at country and sectoral levels. Policies should be particularly cognisant of each country’s economic conditions. The second contribution draws from the empirical findings of Study 2. Utilising a new and comprehensive dataset, the study provides new empirical evidence that RTAs increase the duration of exports in the EAC. That is, it takes 2–3 years for half of the exports to dissipate in the EAC. The policy implication is that there is a need to explore ways in which RTAs can be used to increase the duration of trade in the EAC. Country and product characteristics in the EAC should be taken into account in plans to expand trade opportunities within particular regional markets, if trade relationships are to be extended. The third contribution draws on the empirical findings of Study 3. The study provides new empirical evidence that although RTAs do have a positive effect on economic growth, this varies across countries in the EAC. Empirical results reveal that investment and human capital are growth enhancing, while expansion of domestic credit by the private sector and ‘import openness’ are growth impeding. The policy implication is that there is a need to factor in trade liberalisation through RTAs in economic growth strategies other than via trade openness measures alone.
Xia, Jun. "STATISTICAL MODELS AND ANALYSIS OF GROWTH PROCESSES IN BIOLOGICAL TISSUE." 2016. http://scholarworks.gsu.edu/math_diss/39.
Повний текст джерелаŠlegerová, Lenka. "Hodnocení zdravotní technologie (HTA): léčba karcinomu prsu, případová studie ČR." Master's thesis, 2019. http://www.nusl.cz/ntk/nusl-392652.
Повний текст джерела