[R] Meta-analysis with zero values for mean and sd

Jim Lemon jim at bitwrit.com.au
Sun Jul 10 01:21:16 CEST 2011

On 07/09/2011 08:16 PM, Rosana Ferrero wrote:
> Hi!
> I want to do a meta-analysis with count data for treatement/control cases.
> Mi problem is that I need to use zero values (an informative value) for the
> mean and standard deviation for one of the treatement, but R has a
> problem: "Studies
> with zero values for sd.e or sd.c get no weight in meta-analysis". I can
> agroup the case by Family (byvar=Family).

Hi Rosana,
Your data indicates that in three studies, whatever was being measured 
had a value of zero for each of the three spaghetti worms in the 
treatment group. Maybe they were dead or something. You may be able to 
get away with substituting a very small value (0.1 or something) for the 
SD in these cases. However, I would look very carefully at what this 
means. If, say, the worms are dead, is the measurement between live and 
dead worms meaningful? Just a guess.


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