With "geometric mean 1 CI /3.92", I assume you mean "(upper bound - lower 
bound) / 3.92". Two things:

1) That will give you the SE of the mean, not the SD of the observations (which 
is what you need as input).

2) Probably the CI for the geometric mean was calculated on the log-scale (as 
Michael hinted at). Check if log(upper bound) and log(lower bound) is (within 
rounding error) symmetric around log(geometric mean). Then (log(upper bound) - 
log(lower bound)) / 3.96 * sqrt(n) will give you the SD of the log of the 
values used to compute the geometric mean. Then you could use log(geometric 
mean) and that SD as input. But this would give you the difference of the 
log-transformed geometric means. Not sure if this is what you want to analyze.

Two more articles that may be helpful here:

Friedrich, J. O., Adhikari, N. K., & Beyene, J. (2012). Ratio of geometric 
means to analyze continuous outcomes in meta-analysis: Comparison to mean 
differences and ratio of arithmetic means using empiric data and simulation. 
Statistics in Medicine, 31(17), 1857-1886.

Souverein, O. W., Dullemeijer, C., van 't Veer, P., & van der Voet, H. (2012). 
Transformations of summary statistics as input in meta-analysis for linear 
dose-response models on a logarithmic scale: A methodology developed within 
EURRECA. BMC Medical Research Methodology, 12(57).

Best,
Wolfgang

> -----Original Message-----
> From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org]
> On Behalf Of Michael Dewey
> Sent: Thursday, November 13, 2014 12:36
> To: Purssell, Ed; r-help@r-project.org
> Subject: Re: [R] metafor - code for analysing geometric means
> 
> On 13/11/2014 11:00, Purssell, Ed wrote:
> > ?Dear All
> >
> > I have some data expressed in geometric means and 95% confidence
> intervals.  Can I code them in metafor as:
> >
> > rma(m1i=geometric mean 1, m2i=geometric mean 2, sd1i=geometric mean 1
> CI /3.92, sd2i=geometric mean 2 CI/3.92.......etc, measure="MD")
> 
> Would it not be better to work on the log scale?
> 
> > All of the studies use geometric means.
> >
> > Thanks!
> >
> > Edward
> 
> --
> Michael
> http://www.dewey.myzen.co.uk

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