Misunderstandings about Q and 'Cochran's Q test' in meta-analysis
Misunderstandings about Q and 'Cochran's Q test' in meta-analysis
复制标题
DOI：
10.1002/sim.6632
复制
发表时间：
2016-02-20
影响因子：
2
通讯作者：
Hoaglin, David C.
中科院分区：
文献类型：
--
作者：
Hoaglin, David C.
许多Meta分析报告使用“Cochran‘s Q检验”来评估来自个别研究的效应大小估计的异质性。一些作者引用了W.G.Cochran的工作，但没有意识到Cochran故意不使用Q本身来测试异质性。此外，当不存在异质性时，Q的实际零分布不是‘Cochran的Q检验’所假定的卡方分布。本文回顾了Cochran关于Q的工作，然后讨论了Q的零分布的渐近近似的推导，以及在特定效应大小的情况下导出有限样本矩和相应的近似的工作。这些结果使流行的异质性指数I-2的实施和解释复杂化。此外，事实证明，I-2使用的基于测试的可信区间是基于一种错误的方法。输出Q和I-2的软件应将适当的参考值Q用于特定的效果大小测量和当前的荟萃分析。Q是流行的随机效应Meta分析的德西蒙尼-莱尔德程序的一个关键因素，但该程序和相关程序的假设并不反映Q的实际行为，可能会引入偏差。德西蒙尼-莱尔德手术应该被认为是不可靠的。版权所有(C)2015 John Wiley&Sons，Ltd.
Many meta-analyses report using 'Cochran's Q test' to assess heterogeneity of effect-size estimates from the individual studies. Some authors cite work by W.G. Cochran, without realizing that Cochran deliberately did not use Q itself to test for heterogeneity. Further, when heterogeneity is absent, the actual null distribution of Q is not the chi-squared distribution assumed for 'Cochran's Q test'. This paper reviews work by Cochran related to Q. It then discusses derivations of the asymptotic approximation for the null distribution of Q, as well as work that has derived finite-sample moments and corresponding approximations for the cases of specific measures of effect size. Those results complicate implementation and interpretation of the popular heterogeneity index I-2. Also, it turns out that the test-based confidence intervals used with I-2 are based on a fallacious approach. Software that outputs Q and I-2 should use the appropriate reference value of Q for the particular measure of effect size and the current meta-analysis. Q is a key element of the popular DerSimonian-Laird procedure for random-effects meta-analysis, but the assumptions of that procedure and related procedures do not reflect the actual behavior of Q and may introduce bias. The DerSimonian-Laird procedure should be regarded as unreliable. Copyright (C) 2015 John Wiley & Sons, Ltd.