You may have noted that the x‐axis of the plot uses a logarithmic scale (the distance from 1-2 is the same as that from 2-4 and from 4-8).This is: A)To ensure the correct visual balance between RRs that are positive (1.0) and those that reflect an inverse association (

Question

You may have noted that the x‐axis of the plot uses a logarithmic scale (the distance from 1-2 is the same as that from 2-4 and from 4-8).This is: 
A)To ensure the correct visual balance between RRs that are positive (>1.0) and those that reflect an inverse association (<1.0) 
B)A mistake - linear (arithmetic) scales are easier to work with and interpret 
C)Irrelevant, since the range of RRs is quite small 
D)To allow a very wide range of effect sizes to be included on the one plot

Quizplus · Accepted Answer

Looking closely at the scale, the distance from the intersection with the y‐
axis (the 'no effect' point, RR= 1.0) to an RR of 2.0 (double the risk) is identical to the
distance from this point in the other direction to an RR of 0.5 (half the risk).This
ensures that a point on the plot representing a study with RR=2.0 is equally as far to the
right of the y‐axis as the point for a study with RR= 0.5 is to the left; i.e.on a logarithmic
(log) scale a doubling of risk has the same visual impact as halving it.With an arithmetic
scale, RRs below 1.0 are compressed between 0 and 1.0 y‐axis giving a false impression
of the balance of effects.The log scale does also allow a wider range of RRs to be
included (D) but this is not relevant here and in fact the choice of scale is not critical.

You May Have Noted That the X‐axis of the Plot