Tamura R N, Young S S
Eli Lilly and Company, Greenfield, Indiana 46140.
Biometrics. 1987 Dec;43(4):813-24.
The beta-binomial distribution has been proposed as a model for the incorporation of historical control data in the analysis of rodent carcinogenesis bioassays. Low spontaneous tumor incidences along with the small number and sizes of historical control groups combine to make the moment and maximum likelihood estimates of the beta-binomial parameters deficient. We therefore propose a stabilized moment estimator for one of the parameters. The stabilized moment estimator is similar to the ridge regression estimator and introduces a shrinkage parameter. Computer simulations were run to examine the behavior of the stabilized moment estimator. The effect of the stabilized moment estimator on the score test for dose-related trend is considered both on simulated data and on an example from the literature.
β-二项分布已被提议作为一种模型，用于在啮齿动物致癌生物测定分析中纳入历史对照数据。低自发肿瘤发生率以及历史对照组的数量少和规模小，共同导致β-二项分布参数的矩估计和最大似然估计存在缺陷。因此，我们为其中一个参数提出了一种稳定化矩估计器。该稳定化矩估计器类似于岭回归估计器，并引入了一个收缩参数。进行了计算机模拟以检验稳定化矩估计器的性能。在模拟数据和文献中的一个实例上，都考虑了稳定化矩估计器对剂量相关趋势得分检验的影响。
