Question 4: What kind of horizontal scale is used in Figure 1 and why?
This is a logarithmic scale, where equal intervals represent equal ratios rather than equal differences.
It is used because the outcome is a ratio and an odds ratio of 0.1 is as different from 1, representing no difference between treatments, as is an odds ratio of 10. This makes the confidence intervals symmetrical, because they are calculated for the log of the odds ratio rather than for the odds ratio itself, then antilogged to the natural scale.
Back to question.
Back to Systematic Reviews index.
This page maintained by Martin Bland.
Last updated: 18 February, 2009.