Li Gang, Shih Weichung J, Xie Tailiang, Lu Jiang
Organon Inc., 375 Mt Pleasant Ave., West Orange, NJ 07052, USA.
Biostatistics. 2002 Jun;3(2):277-87. doi: 10.1093/biostatistics/3.2.277.
When designing clinical trials, researchers often encounter the uncertainty in the treatment effect or variability assumptions. Hence the sample size calculation at the planning stage of a clinical trial may also be questionable. Adjustment of the sample size during the mid-course of a clinical trial has become a popular strategy lately. In this paper we propose a procedure for calculating additional sample size needed based on conditional power, and adjusting the final-stage critical value to protect the overall type-I error rate. Compared to other previous procedures, the proposed procedure uses the definition of the conditional type-I error directly without appealing to an extra special function for it. It has better flexibility in setting up interim decision rules and the final-stage test is a likelihood ratio test.
在设计临床试验时，研究人员常常会遇到治疗效果或变异性假设方面的不确定性。因此，在临床试验规划阶段的样本量计算也可能存在问题。在临床试验进行过程中调整样本量最近已成为一种流行策略。在本文中，我们提出了一种基于条件功效计算所需额外样本量，并调整最终阶段临界值以保护总体I型错误率的程序。与之前的其他程序相比，所提出的程序直接使用条件I型错误的定义，无需为其引入额外的特殊函数。在设置中期决策规则方面具有更好的灵活性，并且最终阶段的检验是似然比检验。
