Re: st: geometric means

[Roger Newson <roger.newson@kcl.ac.uk>]

At 14:15 04/05/2005, Mariarosaria wrote:



> dear all,
> is there a way to obtain geometric means when using the following command:
>
>  egen mean_x=mean(x), by(time)
Yes. You should type:

gene logx=log(x)
egen mean_logx=mean(logx), by(time)
gene gmean_x=exp(mean_logx)


If you want to calculate confidence intervals for geometric means and their 
ratios, then you can use the -eform()- option of -regress-. To find out 
about that, download my Stata Tip on this subject, which you can find from 
within Stata by typing

findit gmratio

which will direct you to a .pdf preprint.

Hope this helps.

Roger



--
Roger Newson
Lecturer in Medical Statistics
Department of Public Health Sciences
Division of Asthma, Allergy and Lung Biology
King's College London

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Tel: 020 7848 6648 International +44 20 7848 6648
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  or 020 7848 6605 International +44 20 7848 6605
Email: roger.newson@kcl.ac.uk
Website: http://phs.kcl.ac.uk/rogernewson/

Opinions expressed are those of the author, not the institution.

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