[R-meta] Quick question about multiple independent samples within one study

Guido Schwarzer @c @ending from imbi@uni-freiburg@de
Thu Dec 13 14:17:27 CET 2018

Dear Anna-Lena,

I would suggest that you have a look at Rücker et al. (2017) as well as 
sections 16.5.4 and 16.5.5 of the Cochrane Handbook 

These papers deal with multiple treatment groups, however, the same 
arguments apply if you have different age groups etc. within a study.

In summary, it is fine to include multiple independent groups from a 
study under a fixed effect model. However, you should combine the groups 
within a study under the random effects model.

Best wishes, Guido

Rücker G, Cates CJ, Schwarzer G. Methods for including information from 
multi-arm trials in pairwise meta-analysis. Res Synth Methods. 

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