[R] Mean effect size in meta-analysis using Metafor

[Carlijn .]

Hi all,



I have a question about doing a meta-analysis, in particular a three-level
meta-analysis using Metafor. 

I have estimated the mean overall effect size of males by using two different
ways: 

1. moderator analysis (male = 0, female = 1) using the whole data set

2. intercept-only model with a subset of the data (only males)



The mean effect size estimated by using the categorical moderator analysis
(1) differs considerably from the overall mean effect size estimated in an
intercept-only model using a subset of the data (2). 



Can someone explain this? Which method gives a better estimation of the
effect?



Thank you in advance!

 		 	   		  
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