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光检查依赖于复杂的设计，耗资巨大， 涉及许多女性的健康，准确的权力和样本量计算 是必不可少的。在这些试验中，放射科医生用不同的方法阅读了许多影片。 各种数字机器，以及各种形式的图像处理。 检测准确率的衡量标准是命中率和虚警率 费率。每个医生都会生成几个准确度分数，每个分数对应一种情况。 这些指标是相互关联的。如果一个人使用模拟的精度度量 机器作为数字机器上的精度预测器，另一层 增加了复杂性。这一实验设计导致分析一个通用的 固定和随机重复测量的线性多变量模型 预报器，以及每个细胞中的完整模型。对于这种设计，有几种 提出了功率计算方法。条件幂可以计算为 一组特定的预测值。无条件权力是期望值 所有可能的随机实现上的条件幂 预测者。分位数幂是具有非中心性的条件幂 这与随机预测器的实现相对应， 指定的概率。这些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、图形化的样本量方法 决心。

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.