Adaptive method in the clinical research has been concerned increasingly in the recent years, since the protocol amendments of the on-going clinical trial is becoming more and more common. As a series study of random shifts in clinical research, Chow et al. (2005)considered the case of the target population mean shift, Lu et al. focused on the shift in variance when the population mean is fixed. In this article, we discussed the shift in both mean and variance when the amendments happened in the conduction of the clinical trial. EM algorithm is an efficient method to solve the maximum likelihood estimates of the corresponding parameters, and the complete data information matrix can be obtained by Louis (1982) method. Through a simulation study, the proposed method will be compared to the classical method by ignoring the shift in both mean and variance, we will find the superiority of the proposed method.
Lu, Ying; Chow, Shein-Chung; and Zhang, Zhongzhan, "Considerations to Sample Size in Random Shift among Adjusted Clinical Trials" (June 2010). Duke Biostatistics and Bioinformatics (B&B) Working Paper Series. Working Paper 12.