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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 35 for “"Cox proportional hazards model"”.
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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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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
… Zhao et al. (2013) to deal with 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 …
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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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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
… of this work was to determine if prediction models using quantitative imaging measures in head and neck squamous cell carcinoma (HNSCC) patients could be improved when noise due to imaging was reduced. This was investigated separately for salivary gland function using dynamic contrast …
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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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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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Prolonged tuberculosis-associated immune reconstitution inflammatory syndrome: characteristics and risk factors
… Risk factors for TB-IRIS were analysed using Wilcoxon rank sum test, Fisher's exact test, multivariate logistic regression and Cox proportional hazards model. In a separate set of analyses, risk factors for relapsing after a 4-week course of prednisone for treatment of TB-IRIS were analysed. …
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Improving applicability of the non-monotone unified estimate for missing data
… inverse probability weighting that uses "working models" to extract information from individuals with partially observed data. When the probability an individual has missing data can be accurately modeled but the distribution of the data is difficult to model the unified approach is an attractive …
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Impact of data-dependent model selection on inference
… thesis, I consider the problem of accounting for model uncertainty in a parametric regression model with focus on the uncertainty involved in selection of the optimal transformation of a continuous predictor in the Cox proportional hazards model (Cox, 1972). I use the minimum AIC approach to …
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Two Applied Economics Essays: Trade Duration in U.S. Fresh Fruit and Vegetable Imports & Goods-Time Elasticity of Substitution in Household Food Production for SNAP participants and nonparticipants
… survival analysis (Kaplan Meier estimates and Cox proportional hazards model) as well as count data models. Our results indicate that SPS treatment requirements positively impact the duration of trade while new market access has the opposite effect. Other factors typically included in trade …
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Analysis of clustered competing risks with application to a multicentre clinical trial
… it gain a wide applicability in statistically modelling research. The methodological developments of time-to-event analysis that have been widely adopted are: (i) The Kaplan-Meier method, for estimating the survival function; (ii) The log-rank test, for comparing the equality of two or more …
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