Gilbert E S
Radiat Res. 1984 Jun;98(3):591-605.
The effects of random dose measurement errors on analyses of atomic bomb survivor data are described and quantified for several analytical procedures. It is found that the ways in which measurement error is most likely to mislead are through downward bias in the estimated regression coefficients and through distortion of the shape of the dose-response curve. The magnitude of the bias and the power for testing the hypothesis of no effect are evaluated for several dose treatments including the use of grouped and ungrouped data, analyses with and without substituting 600 rad for estimated doses exceeding this value, and analyses which exclude doses exceeding 200 rad. The calculations are based on a model in which the error distributions are assumed to be log normal with standard deviations that are 0, 30, and 50%, respectively, of the true dose values. Results are limited to a dose-response function which is linear on total dose. It is found that the commonly applied practice of substituting 600 rad for doses exceeding this value definitely reduces bias in the presence of error. Restricting analyses to doses less than 200 rad reduces bias even more but at the price of considerable loss of power. Both the bias and the power for analyses based on grouped data are very close to the respective bias and power with ungrouped data.
针对几种分析程序，描述并量化了随机剂量测量误差对原子弹幸存者数据的影响。研究发现，测量误差最有可能产生误导的方式是估计回归系数的向下偏差以及剂量反应曲线形状的扭曲。针对几种剂量处理，评估了偏差的大小和检验无效应假设的功效，包括使用分组和未分组数据、在估计剂量超过该值时用600拉德替代以及排除超过200拉德的剂量进行分析。计算基于一个模型，其中假设误差分布为对数正态分布，标准差分别为真实剂量值的0%、30%和50%。结果仅限于总剂量呈线性的剂量反应函数。研究发现，对于超过该值的剂量用600拉德替代这一常用做法，在存在误差的情况下确实会减少偏差。将分析限制在小于200拉德的剂量会进一步减少偏差，但代价是功效大幅损失。基于分组数据的分析的偏差和功效与基于未分组数据的相应偏差和功效非常接近。
