Cluster randomization trials randomize groups (called clusters) of subjects (called subunits) between intervention arms, and observations are collected from each subject. In this case, subunits within each cluster share common frailties, so that the observations from subunits of each cluster tend to be correlated. Oftentimes, the outcome of a cluster randomization trial is a time‐to‐event endpoint with censoring. In this article, we propose a closed form sample size formula for weighted rank tests to compare the marginal survival distributions between intervention arms under cluster randomization with possibly variable cluster sizes. Extensive simulation studies are conducted to evaluate the performance of our sample size formula under various design settings. Real study examples are taken to demonstrate our method.

中文翻译：

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具有事件发生时间终点的整群随机试验的样本量计算

集群随机化试验在干预组之间随机分组（称为集群）受试者（称为亚单位），并从每个受试者收集观察结果。在这种情况下，每个集群内的子单元具有共同的弱点，因此来自每个集群的子单元的观察往往是相关的。通常，整群随机化试验的结果是带有删失的事件发生时间终点。在本文中，我们提出了一个用于加权秩检验的封闭式样本大小公式，以比较集群随机化下干预组之间的边际生存分布与可能的可变集群大小。进行了广泛的模拟研究以评估我们的样本量公式在各种设计设置下的性能。采用真实的研究示例来演示我们的方法。