Weighted Log Rank Type Statistics for Comparing Survival Curves when There is a Time Lag in the Effectiveness of Treatment
针对长期治疗试验中效果存在滞后期的情形，提出了两种加权对数秩统计量，在多种滞后情况下效率优于传统对数秩统计量，且计算简便。
In certain long-term treatment trials, one expects some lag period before the treatment is fully effective. This paper presents two weighted log rank type statistics designed to have good efficiency over a wide range of lags: a maximin efficiency robust statistic and a simplified version of this statistic. Both statistics can be computed as easily as the log rank statistic. Asymptotic efficiency calculations, supported by small sample simulations, show that the two proposed statistics are substantially more efficient than the conventional log rank statistic in certain lag situations with comparatively little efficiency loss relative to the log rank statistic when no lag exists. We recommend the maximin statistic for situations where a lag is expected but cannot be specified precisely in advance.