Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 119 for “"Cox proportional hazards"”.
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Extending Sample Size Calculation for the Cox Proportional Hazards Model
… used sample size formula derived under the Cox proportional hazards (PH) model may not be proper to design a survival trial with a cure fraction, since the PH model assumption may be violated. To account for a cure fraction, the PH cure model is widely used in practice, where a PH model is …
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Reframing Cox Proportional Hazards Model for Big Data and Neural Networks
… outcome. To do this, it is common to assume a proportional hazards model and fit a proportional hazards regression (or Cox regression). A log-concave objective function known as the “partial likelihood” is maximized to fit the Cox proportional hazards model. For moderate-sized datasets, an …
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A Cox proportional hazards-cash flow model for bank failure prediction
This research uses the Cox proportional hazard model and bank cash flow information to determine whether adding cash flow information will improve current bank failure prediction methods. In two published papers it has been shown that the Cox model performs as well as other models with respect to …
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Statistical model selection techniques for the cox proportional hazards model: a comparative study
… response variable. In this dissertation, common Cox proportional hazards model selection techniques and a random survival forest technique were compared using five performance criteria measures. These performance measures were concordance index, integrated area under the curve, and , and R2 . To …
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Unified Approach to Partially Linear Model and Cox Proportional Hazards Model with Missing Covariates
… partially linear model (Engle et al., 1986) and Cox proportional hazards model (Cox, 1972) with missing covariates. The unified approach possesses some superior characteristics in dealing with regression models with missing data. First, the unified approach requires less extra assumptions to be …
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The analysis of limit orders using the Cox proportional hazards model with independent competing risks
I apply the Cox proportional hazards model with independent competing risks to study the hazard rates of executed, cancelled, and partially executed limit orders submitted for Microsoft to the Island ECN for one day. The instantaneous probability of execution increases with decreases in the buy …
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Modelling hepatotoxicity in HIV/TB co-infected patients: extensions of the Cox Proportional Hazards Model
… The statistical objectives are to fit a Cox regression model, the resolution model of hepatotoxicity, and the extended Cox models for recurring events, including the Andersen Gill (AG) model, the Shared frailty model, the Prentice, Williams and Peterson (PWP) total time (TT) model, the …
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A comparison of methods for analysing interval-censored and truncated survival data
… methods for analysing right-censored data: the Cox proportional hazards model (Cox, 1972), the Buckley-James regression model (Buckley and James, 1979) and the accelerated failure time model. These models are extended to incorporate the analysis of interval-censored and left-truncated data. The …
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Quantile Regression With Censored Data
… Analysis; Quantile Regression; Kaplan-Meier; the Cox Proportional Hazards Model; Accelerated Failure Time Model.
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Improving applicability of the non-monotone unified estimate for missing data
… the unified estimate and its application to the Cox proportional hazards model for survival data. We present a new R program which can be used to easily fit the unified estimate for generalized linear models or Cox proportional hazards models. Possible hypothesis tests for the fit of the unified …
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Application of dynamic prediction models for longitudinal biomarkers and clinical outcomes in low and middle-income settings
… over traditional approaches such as the Cox proportional hazards-based prediction model. In addition to applying an extension of existing models to correctly model semicontinuous biomarker data (two-part joint model), this thesis challenges this assumption by applying dynamic prediction …
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Sample Size Calculation Based on the Semiparametric Analysis of Short-term and Long-term Hazard Ratios
… sample size formulae for survival data with non-proportional hazard functions under both fixed and contiguous alternatives. Sample size determination has been widely discussed in literature for studies with failure-time endpoints. Many researchers have developed methods with the assumption of …
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Nuisance Parameter Estimation in Survival Models
The Cox proportional hazards model is the most commonly used method for right-censored data. Unfortunately, the interpretation of the hazard ratio is non-intuitive and it is commonly misinterpreted as a relative risk. This motivates alternative methods with more intuitive interpretations that avoid …
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Quantitative Imaging For Precision Medicine In Head and Neck Cancer Patients
… with CT images were used to create and test a Cox proportional hazards model for overall survival. Those patients with the same imaging protocol were subset and a new Cox proportional hazards model was created and tested in order to determine if the reduction in noise due to controlling the …
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An Analysis of All-Cause Mortality on Patients with Sickle Cell Disease and Kidney Disease using Propensity Score Matching
<p>In this work, we provide an overview of the Cox proportional hazards model for time to event or survival analysis and the notion of propensity score matching to deal with confounding factors. A full analysis is reported in Chapter 2 concerning mortality for in-center dialysis patients with …
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Contemporary Outcomes of Distal Lower Extremity Bypass for Chronic Limb Threatening Ischemia and a Model Based Comparison with Non-Surgical Therapies
… analysis with death as a competing risk. A cox proportional hazards model was then fit to the pooled data in a stepwise fashion with death as a competing risk, including evaluations for appropriate transformation, time dependency and interactions for each included covariate, and hazard …
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Statistical inference for residual time quantiles in regression models for censored time-to-event data
… time under a few different settings: the Cox proportional hazards model (with fixed and with external time-varying covariates) and the additive hazards model. In each setting, we consider point estimation, asymptotic properties, variance estimation, confidence interval construction, and …
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Evaluation of the Survival Effect for Various Treatment Modalities Among Stage II and III Rectal Cancer Patients in California, 1994-2009
… PreOP CRT with those receiving PostOP CRT. Cox proportional hazards regression was used to assess survival over 192 months in both study groups, adjusting for date of surgery, stage, age, gender, race/ethnicity, and socioeconomic status (SES).</p> <p><strong>Results: </strong>The Cox …
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Dollar Stores and Supermarket Survivability in Non-metropolitan US Communities
… grocery stores, Kaplan Meier curves and Cox proportional hazards models were used for survival analysis of grocery stores. The findings of the models used imply that the presence of dollar stores is not associated with increasing the likelihood of grocery store closures. </p>
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Predicting intensive care unit patient outcomes through patient similarity
… pressure measurement. Using this information, a Cox Proportional Hazards model was built to map the multivariate time series of input data to a univariate time series, which was used to match the patient to a cohort of similar patients. Based on the cohort, this model predicted the probability of …
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