Schoenfeld D A
Biometrics. 1983 Jun;39(2):499-503.
A formula is derived for determining the number of observations necessary to test the equality of two survival distributions when concomitant information is incorporated. This formula should be useful in designing clinical trials with a heterogeneous patient population. Schoenfeld (1981, Biometrika 68, 316-319) derived the asymptotic power of a class of statistics used to test the equality of two survival distributions. That result is extended to the case where concomitant information is available for each individual and where the proportional-hazards model holds. The loss of efficiency caused by ignoring concomitant variables is also computed.
推导了一个公式，用于在纳入伴随信息时确定检验两个生存分布相等所需的观察次数。该公式在设计具有异质患者群体的临床试验中应会很有用。舍恩菲尔德（1981年，《生物统计学》68卷，316 - 319页）推导了用于检验两个生存分布相等的一类统计量的渐近功效。该结果被扩展到每个个体都有伴随信息且比例风险模型成立的情况。还计算了忽略伴随变量所导致的效率损失。
