Recommendations for examining and interpreting funnel plot asymmetry in meta-analyses of randomised controlled trials

@article{Sterne2011RecommendationsFE,
  title={Recommendations for examining and interpreting funnel plot asymmetry in meta-analyses of randomised controlled trials},
  author={Jonathan A. C. Sterne and Alex Sutton and John P. A. Ioannidis and Norma C. Terrin and David Jones and Joseph Lau and James R. Carpenter and Gerta R{\"u}cker and Roger M. Harbord and Christopher H. Schmid and Jennifer Marie Tetzlaff and Jonathan J. Deeks and Jaime L. Peters and Petra Macaskill and Guido Schwarzer and Sue Duval and Douglas G. Altman and David Moher and Julian P. T. Higgins},
  journal={BMJ : British Medical Journal},
  year={2011},
  volume={343}
}
Funnel plots, and tests for funnel plot asymmetry, have been widely used to examine bias in the results of meta-analyses. Funnel plot asymmetry should not be equated with publication bias, because it has a number of other possible causes. This article describes how to interpret funnel plot asymmetry, recommends appropriate tests, and explains the implications for choice of meta-analysis model 
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A new graphical method, the Doi plot, to visualize asymmetry and also a new measure, the LFK index, to detect and quantify asymmetry of study effects in Doi plots are proposed and demonstrated.
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