Bayesian topics in biostatistics : treatment selection, sample size, power, and misclassification.

Bayesian methodology is implemented to investigate three problems in biostatistics. The first problem considers using biomarkers to select optimal treatments for individual patients. A Bayesian adaptation of the selection impact (SI) curve developed by Pepe and Song (2004) is investigated. The second problem considers a Bayesian approach for determining specific sample sizes to achieve a desired range of power for fixed-dose combination drug trials. Sidik and Jonkman (2003) developed a sample size formula using the intersection-union test for testing the efficacy of combination drugs. Our results are compared to their frequentist approach. The third problem considers response misclassification in fixed-dose combination drug trials under two scenarios: when the sensitivity and specificity are known, and when the sensitivity and specificity are unknown but have specified informative prior structures.