Murray David M, Blistein Jonathan L
University of Memphis, USA.
Eval Rev. 2003 Feb;27(1):79-103. doi: 10.1177/0193841X02239019.
This study reports intraclass correlation (ICC) for dependent variables used in group-randomized trials (GRTs). The authors also document the effect of two methods suggested to reduce the impact of ICC in GRTs; these two methods are modeling time and regression adjustment for covariates. They coded and analyzed 1,188 ICC estimates from 17 published, in press, and unpublished articles representing 21 studies. Findings confirm that both methods can improve the efficiency of analyses shown to be valid across conditions common in GRTs. Investigators planning GRTs should obtain ICC estimates matched to their planned analysis so that they can size their studies properly.
本研究报告了群组随机试验（GRT）中使用的因变量的组内相关系数（ICC）。作者还记录了为减少ICC对GRT影响而提出的两种方法的效果；这两种方法分别是对时间进行建模以及对协变量进行回归调整。他们对来自17篇已发表、待发表和未发表文章（代表21项研究）的1188个ICC估计值进行了编码和分析。研究结果证实，这两种方法都可以提高在GRT常见条件下有效的分析效率。计划开展GRT的研究者应获取与计划分析相匹配的ICC估计值，以便能合理确定研究规模。
