Plots the treatment difference for trials against the size of the
trial (or other specified variable). Asymmetry in the plot often
indicates publication bias. Generic, with methods for meta-analysis
objects.
further arguments to be passed from or to methods.
Details
With the default value of size the plot should appear as a
upwards-pointing funnel shape. Publication bias often causes one side
of the funnel to be trimmed near the base. The mirror plot
creates a symmetric funnel by reflecting the plot around the
summ value. In the presence of publication bias the added
points will separate from the real studies.