Physical Sciences and Mathematics Commons^™

Modeling Sequential Event Times Using Family Data, Balakumar Swaminathan

Electronic Thesis and Dissertation Repository

In genetic epidemiology, families harboring certain genetic mutations are predisposed to successive cancers in their lifetime. This thesis aims to provide reliable estimates of relative risk and age-dependent cumulative risks (penetrance) associated with the mutated gene for successive cancers. We develop a statistical framework for modeling sequential event times arising from family data. A shared frailty model is employed to incorporate the dependence between the two event times. Because families are ascertained through non-random sampling, an ascertainment-corrected retrospective likelihood approach is proposed to account for the non-ignorable sampling design. Simulation studies demonstrate that our proposed method provides unbiased and reliable …

Simultaneous Confidence Intervals For Risk Ratios In The Many-To-One Comparisons Of Proportions, Jungwon Shin

Electronic Thesis and Dissertation Repository

For many-to-one comparisons of independent binomial proportions using their ratios, we propose the MOVER approach generalizing Fieller's theorem to a ratio of proportions by obtaining variance estimates in the neighbourhood of confidence limits for each proportion. We review two existing methods of inverting Wald and score test statistics and compare their performance with the proposed MOVER approach with score limits and Jeffreys limits for single proportions. As an appropriate multiplicity adjustment incorporating correlations between risk ratios, a Dunnett critical value is computed assuming a common, constant correlation of 0.5 instead of plugging in sample correlation coefficients. The simulation results suggest …

Heterogeneity Issues In The Meta-Analysis Of Cluster Randomization Trials., Shun Fu Chen

Electronic Thesis and Dissertation Repository

An increasing number of systematic reviews summarize results from cluster randomization trials. Applying existing meta-analysis methods to such trials is problematic because responses of subjects within clusters are likely correlated. The aim of this thesis is to evaluate heterogeneity in the context of fixed effects models providing guidance for conducting a meta-analysis of such trials. The approaches include the adjusted Q statistic, adjusted heterogeneity variance estimators and their corresponding confidence intervals and adjusted measures of heterogeneity and their corresponding confidence intervals. Attention is limited to meta-analyses of completely randomized trials having a binary outcome. An analytic expression for power of …

Confidence Intervals For Comparison Of The Squared Multiple Correlation Coefficients Of Non-Nested Models, Li Tan Jr.

Electronic Thesis and Dissertation Repository

Multiple linear regression analysis is used widely to evaluate how an outcome or responsevariable is related to a set of predictors. Once a final model is specified, the interpretation of predictors can be achieved by assessing the relative importance of predictors.

A common approach to predictor importance is to compare the increase in squared multiple correlation for a given model when one predictor is added to the increase when another predictor is added to the same model.

This thesis proposes asymmetric confidence-intervals for a difference between two correlated squared multiple correlation coefficients of non-nested models. These new proceduresare developed by …