[R-meta] Results interpretation publication bias
Dr. Guido Schwarzer
gu|do@@chw@rzer @end|ng |rom un|k||n|k-|re|burg@de
Mon Apr 3 18:44:43 CEST 2023
@Michael: the funnel plots show contours for significance levels p < 0.01 and p < 0.05. These contour-enhanced funnel plots (see doi: 10.1016/j.jclinepi.2007.11.010 ) can be used to evaluate whether funnel plot asymmetry is due to publication bias (i.e., if small unprecise studies are only "published" if they are statistically significant which is not the case here).
I agree with Michael that the large funnel plot looks odd. I guess that the single very precise study at the top right side is triggering the statistical significance of tests for funnel plot asymmetry. This said, the result of the trim-and-fill method does not make any sense here as all added studies have correlations above 1!
Did you have a look at the result of the Thompson-Sharp test for funnel plot asymmetry (e.g., meta::metabias(..., method = "Thompson")? This test works better than the Egger test in heterogeneous meta-analyses.
Furthermore, you could have a look at the results of some sensitivity analyses such as limit meta-analysis (metasens::limitmeta), Copas selection model (metasens::copas) or selection models (metafor::selmodel).
More information about the R-sig-meta-analysis