I have a simple question.
I have reviewed some meta-analyses papers and found out that the interval between upper & lower limit and the mean differs; such as OR 0.85 (0.74-0.98).
I am wondering why these values are different.
It would be grateful if you add any reference about this issue.
Martin Bland’s paper on the odds ratio (link) explains this. Shortly, the confidence limits are calculated on the log-odds scale, where they are symmetric. They are then backtransformed to the odds-ratio scale where they are asymmetric. That’s why graphs of odds ratios (and risk ratios etc.) should use logarithmic scales instead of linear ones (see this paper).