Power and Sample Size Methods for Mammography Trials

描述（由申请人提供）：因为比较数字和 模拟乳房X线摄影依赖于复杂的设计，花费大量的金钱， 涉及许多妇女的健康，精确的功效和样本量计算 是必不可少的。 在这些试验中，放射科医生使用不同的 各种各样的数字机器，以及各种形式的图像处理。 检测准确性的度量是命中率和虚警 率 每个医生都会生成几个准确性分数，每个条件一个。 这些措施是相互关联的。 如果一个人使用模拟的准确性措施， 机器作为数字机器精度的预测器，另一层 增加了复杂性。 这种实验设计导致分析一种通用的 固定和随机重复测量的线性多变量模型 预测器，以及每个单元中的完整模型。 对于这种设计， 提出了功率计算。 条件功效可计算为 一组特定的预测值。 无条件功率是期望值 条件功率在所有可能的随机实现的随机 预测器 分位数幂是具有非中心性的条件幂 这对应于随机预测器的实现， 特定概率。 理论推导将导致易于使用 软件和描述性示例。 这些将为放射科医生提供工具， 快速计算和交互式图形方法来确定样本量 保持战略定力

DESCRIPTION (provided by applicant): Because trials to compare digital and analog mammography rely on complex designs, cost large amounts of money and involve the health of many women, accurate power and sample size calculations are essential. In these trials, radiologists read many films using different sorts of digital machines, and with varying forms of image processes. Measures of the accuracy of detection are the hit rate, and the false alarm rate. Each doctor generates several accuracy scores, one for each condition. These measures are correlated. If one uses an accuracy measure for analog machines as a predictor of accuracy on digital machines, another layer of complexity is added. This experimental design leads to analyzing a General Linear Multivariate Model for repeated measures, both fixed and random predictors, and a full model in every cell. For this design, several sorts of power calculations are proposed. The conditional power can be calculated for a specific set of predictor values. Unconditional power is the expected value of conditional power over all possible stochastic realizations of the random predictors. Quantile power is the conditional power with the noncentrality that corresponds to a realization of the random predictors that occurs with specified probability. The theoretical derivations will lead to easily used software and descriptive examples. These will give radiologists tools for rapid calculation and an interactive, graphical approach to sample size determination.