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Re: st: Meta-analysis of SMRs


From   <dg4@nyu.edu>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Meta-analysis of SMRs
Date   Wed, 01 Sep 2004 16:28:42 -0400

Many researchers add one to a frequency before taking the log. If you do that for both observed and expected frequencies, your problem will be solved.
   - David Greenberg, Sociology Deparment, New York University

----- Original Message -----
From: "Fenty, J." <jf48@leicester.ac.uk>
Date: Wednesday, September 1, 2004 7:41 am
Subject: st: Meta-analysis of SMRs

> Dear statlist
> 
> I am conducting meta-analyses of SMRs using the -meta- command 
> which works fine until you have observed values of zero. I am 
> using the formulae
> 
>                	log(SMR) = log(observed/expected)
>                	se(log(SMR)) = 1/sqrt(observed)
> 
> and both are undefined when the observed value=0. Does anyone have 
> any suggestions for dealing with this situation other than
> omitting studies with zeroes or combining them with other studies? 
> Are there other formulae to calculate se(log(SMR)) which is not 
> based solely on the observed value?
> 
> Many thanks,
> 
> Justin Fenty
> 
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