Dixon D O, Simon R
National Cancer Institute, Bethesda, MD 20892.
J Clin Epidemiol. 1988;41(12):1209-13. doi: 10.1016/0895-4356(88)90025-x.
Formulas are derived for determination of the number of patients needed in a prospective comparison of survival curves, when the control group patients have already been followed for some period. Although an explicit formula for the required sample size is not available, the computing is straightforward, and tables of examples are presented. Situations are described when one might need to allocate some new patients to the control group, rather than exclusively to the experimental group.
当对照组患者已经随访了一段时间后，推导了用于确定前瞻性比较生存曲线所需患者数量的公式。虽然没有明确的所需样本量公式，但计算很简单，并给出了示例表。描述了在哪些情况下可能需要将一些新患者分配到对照组，而不是仅分配到实验组。
