Comparision of group sequential designs and adaptive designs from sample size with power analysis in survival analysis studies and an application

In clinical trails, it is important to decide which method used for treatment of illness especially fatal illness has more effect on survival times. The aim of this study is to compare from sample size and power analysis the group sequential designs and adaptive designs which are used usually in clinical trials recent times.This thesis consists five chapter. At the first chapter, a short information is given about the subject. At the second chapter, the group sequential test methods are viewed and the survival analyze is dealed. At the third chapter adaptive design methods, its properties, its advantages and disadvantages are put in an apperiance.At the fourth chapter applications are made. First application is examining group sequential test methods on survival analyses and comparing the power analyses of spending functions by group sequential designs and adaptive designs. It is understood that O?Brien&Fleming spending function?s power is higher than Pocock?s for both designs. Second application is made on calculation of sample size. It?s founded that adaptive designs require less sample size and events than group sequential designs at the same power value. The last application is made on recalculation of sample size which is the one of major advantage of adaptive designs. The results of the applications are argued at last chapter of the study.Keywords: Adaptive Design, Group Sequential Design, Survival Analyze, Sample Size, Spending Functions, Power