Kang S S, Koehler K J
Department of Computer Science and Statistics, Kwan Dong University, Kangwon-Do, South Korea.
Biometrics. 1997 Sep;53(3):885-99.
Life-table methodology for interval-censored survival times is used to estimate marginal survival probabilities from data consisting of independent cohorts of correlated responses. We restrict our attention to situations where response times within cohorts are exchangeable and the marginal survival distributions are the same for all individuals within any cohort. A modification of the Greenwood formula is derived for estimating variances and covariances of the estimates of the marginal survival probabilities. Simulation results show that this formula provides accurate adjustments for within-cohort correlations in finite samples. Comparisons with a nonparametric maximum likelihood estimator indicate negligible loss in efficiency from using simple life-table estimators of marginal survival probabilities that ignore the within-cohort correlations. Data from an angioplasty study where more than one procedure is performed on some patients are used to illustrate this methodology.
用于区间删失生存时间的生命表方法，是从由相关反应的独立队列组成的数据中估计边际生存概率。我们将注意力限制在队列内反应时间可交换且任何队列中所有个体的边际生存分布相同的情况。推导了Greenwood公式的一种修正形式，用于估计边际生存概率估计值的方差和协方差。模拟结果表明，该公式在有限样本中能对队列内相关性进行准确调整。与非参数最大似然估计器的比较表明，使用忽略队列内相关性的简单生命表边际生存概率估计器导致的效率损失可忽略不计。来自一项血管成形术研究的数据（其中一些患者接受了不止一种手术）被用来阐述这种方法。
