Dear Editor,

We recently published in the journal a new plot for detecting asymmetry in meta-analysis.1 This plot is gaining popularity but our original publication did not set guidelines for rendering the plot and so this has been rendered in different ways by researchers. In a bid to make this uniform, the following guidelines should be adhered to when rendering with MetaXL (http://www.epigear.com):

1. The marker size should not be less than 8

2. The marker should not be filled in

3. The font size and label size (x and y axes) should be a minimum of 12

4. Most importantly, the y-axis height should be twice the width of the x-axis and this can be achieved by dragging the edges of the plot output box to resize it

To demonstrate this, Fig. 1 is the standard output from MetaXL and Fig. 2 then applies step 1 to step 4 to make it render properly. This plot is to resemble an inverted funnel when symmetry is present, and thus the last step is crucial without which the funnel shape does not become obvious.

Figure 1. Wrongly rendered Doi plot with font size 8, marker size 6, filled markers and width greater than its height.

Figure 2. The same plot as in Figure 1 correctly rendered with font size 12, marker size 8, non-filled markers and width half of its height.

Reference