Azen S P, Roy S, Pike M C, Casagrande J, Mishell D R
Am J Obstet Gynecol. 1977 Jun 1;128(3):329-35. doi: 10.1016/0002-9378(77)90632-9.
An improved statistical method for assessing the efficacy of intrauterine contraception is presented. This method, called the log-rank method, is based on a daily life table, which yields the best estimates of the cumulative net termination probabilities. It provides a sensitive chi-square test statistic to detect differences among these probabilities for two or more contraceptive devices. When three or more devices are compared, the chi-square statistic may be partitioned into additive components representing comparisons among groups of devices. The log-rank method also permits adjusting for differences among subgroups by controlling for factors such as parity or age. Although calculations may be performed on a desk calculator, a FORTRAN-IV computer program is made available to interested researchers.
本文提出了一种评估宫内避孕效果的改进统计方法。这种方法称为对数秩检验法，它基于日常生活表，能得出累积净终止概率的最佳估计值。它提供了一个灵敏的卡方检验统计量，用于检测两种或更多种避孕器具在这些概率上的差异。当比较三种或更多种器具时，卡方统计量可被分解为代表器具组间比较的可加性成分。对数秩检验法还允许通过控制诸如胎次或年龄等因素来调整亚组间的差异。虽然计算可以用台式计算器进行，但已为感兴趣的研究人员提供了一个FORTRAN-IV计算机程序。
