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Power and Sample Size Methods for Mammography Trials

乳腺 X 光检查试验的功率和样本量方法

基本信息

批准号：
7922463
负责人：
Deborah Helen Glueck
金额：
$ 5.4万
依托单位：
UNIVERSITY OF COLORADO DENVER
依托单位国家：
美国
项目类别：
财政年份：
2009
资助国家：
美国
起止时间：
2009-09-01 至 2011-02-28
项目状态：
已结题

项目摘要

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.

由于比较数字和模拟乳房X光检查的试验依赖于复杂的设计、花费大量资金并涉及许多女性的健康，因此准确的功效和样本量计算至关重要。在这些试验中，放射科医生使用不同类型的数字机器和不同形式的图像处理来阅读许多胶片。检测准确性的衡量标准是命中率和误报率。每位医生都会生成几个准确度分数，每个分数对应一种情况。这些措施是相关的。如果使用模拟机器的精度测量作为数字机器精度的预测指标，则会增加另一层复杂性。该实验设计导致分析通用线性多元模型的重复测量、固定和随机预测变量以及每个单元格中的完整模型。对于该设计，提出了几种功率计算。可以针对一组特定的预测变量值计算条件功效。无条件功效是随机预测变量的所有可能随机实现的条件功效的期望值。分位数功效是具有非中心性的条件功效，对应于以指定概率发生的随机预测变量的实现。理论推导将带来易于使用的软件和描述性示例。这些将为放射科医生提供快速计算工具和确定样本量的交互式图形方法。