Schill Walter, Wild Pascal, Pigeot Iris
Bremer Institut für Präventionsforschung und Sozialmedizin, Linzer Str. 10, D-28359 Bremen, Germany.
Comput Methods Programs Biomed. 2007 Nov;88(2):175-81. doi: 10.1016/j.cmpb.2007.08.002. Epub 2007 Sep 14.
We present a software tool for planning two-phase case-control studies assuming categorical covariates. Two-phase designs, in which validation or complete information data are sampled stratified both on a dichotomous outcome and a covariate from a first-phase study with incomplete data, result in efficient estimates compared to standard designs. Efficiency and power depend on sample size, sampling fractions within each stratum x outcome cell, distributional assumptions and the regression model. Our software, called Two-Phase Planning Tool (or 2P Planning Tool), offers a graphical user interface (GUI) to organize and input the relevant anticipated entities and calculates a normed, expected two-phase case-control study. The 2P Planning Tool is especially helpful in selecting a stratification. The data are output into an Excel-sheet, which in turn can be read into a standard statistics package to perform "experimental" power calculations. Its use is illustrated by an example from epidemiology. Software for analyzing logistic two-phase studies is also provided.
我们展示了一种用于规划假设分类协变量的两阶段病例对照研究的软件工具。两阶段设计中，在具有不完整数据的第一阶段研究中，根据二分结果和协变量对验证或完整信息数据进行分层抽样，与标准设计相比，能得到更有效的估计。效率和功效取决于样本量、每个分层×结果单元格内的抽样比例、分布假设以及回归模型。我们的软件名为两阶段规划工具（或2P规划工具），提供了一个图形用户界面（GUI）来组织和输入相关的预期实体，并计算标准化的、预期的两阶段病例对照研究。2P规划工具在选择分层方面特别有用。数据输出到一个Excel工作表中，该工作表又可以读入标准统计软件包以进行“实验性”功效计算。通过一个流行病学实例说明了其用法。还提供了用于分析逻辑两阶段研究的软件。
