Sandvik L, Erikssen J, Mowinckel P, Rødland E A
Medstat Research A/S, Lillestrøm, Norway.
Stat Med. 1996 Jul 30;15(14):1587-90. doi: 10.1002/(SICI)1097-0258(19960730)15:14<1587::AID-SIM279>3.0.CO;2-F.
The assessment of sample size in clinical trials comparing population means requires a variance estimate of the main efficacy variable. When this variance estimate has a low precision, it may be appropriate to use the data from the first patients entered in the trial ('internal pilot study') to estimate the sample size. We suggest a method for determining the size of internal pilot studies, which aims at ensuring that this size is as large as possible, but not larger than 'the optimal size' of the planned study. Advantages and limitations of the method are discussed.
在比较总体均值的临床试验中，样本量的评估需要对主要疗效变量进行方差估计。当该方差估计的精度较低时，利用试验中首批入组患者的数据（“内部预试验”）来估计样本量可能是合适的。我们提出了一种确定内部预试验规模的方法，其目的是确保该规模尽可能大，但不超过计划研究的“最优规模”。文中讨论了该方法的优缺点。
