Powerful and cost-efficient designs for longitudinal intervention studies with two treatment groups
Powerful and cost-efficient designs for longitudinal intervention studies with two treatment groups
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DOI：
10.3102/1076998607302630
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发表时间：
2008-03-01
影响因子：
2.4
通讯作者：
Moerbeek, Miriam
中科院分区：
文献类型：
--
作者：
Moerbeek, Miriam
在纵向干预研究的设计阶段，需要确定三个问题：人数、人均重复测量次数和研究持续时间。多项式效应在不同人之间的不同程度和辍学模式也影响到检测干预效果的统计能力。这篇文章提供了一个框架，允许研究人员计算拟议设计的功率，并根据成本和样本大小比较替代设计。一个多项式效应随人变化的多水平回归模型被用来将反应与时间联系起来。这些人在研究中的停留时间是使用生存函数来建模的。
Three issues need to be decided in the design stage of a longitudinal intervention study: the number of persons, the number of repeated measurements per person, and the duration of the study. The degree to which polynomial effects vary across persons and the drop-out pattern also influence the statistical power to detect intervention effects. This article presents a framework that allows researchers to calculate the power of a proposed design and compare alternative designs on the basis of their costs and sample sizes. A multilevel regression model with polynomial effects varying across persons is used to relate response to time. The persons' length of stay in the study is modeled using a survival function.