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[R-meta] Meta-analysis Hedges g - comparisons with same placebo

Gerta Ruecker 
Dear Roberto,

it is a network meta-analysis what you are planning? Do you think of 
multi-arm studies including a placebo group? If so, and if it is the 
same placebo that is compared to several antidepressants, then I think 
there is no problem. The different placebo groups in different studies 
provide independent information and network meta-analysis may in fact 
increase precision (provided you have loops in your network), but this 
is exactly what network meta-analysis is intended to do.

To avoid misunderstandings: What you should not do is to use a placebo 
group in a multi-arm study twice in a pairwise meta-analysis without 
adjustment.

For an introduction, see 
http://onlinelibrary.wiley.com/doi/10.1002/jrsm.1259/full .

Best,

Gerta

Thread (8 messages)

P. Roberto Bakker Meta-analysis Hedges g - comparisons with same placebo Oct 17 Gerta Ruecker Meta-analysis Hedges g - comparisons with same placebo Oct 18 P. Roberto Bakker Meta-analysis Hedges g - comparisons with same placebo Oct 18 Gerta Ruecker Meta-analysis Hedges g - comparisons with same placebo Oct 18 Viechtbauer Wolfgang (STAT) Meta-analysis Hedges g - comparisons with same placebo Oct 19 P. Roberto Bakker Meta-analysis Hedges g - comparisons with same placebo Oct 19 Viechtbauer Wolfgang (STAT) Meta-analysis Hedges g - comparisons with same placebo Oct 19 P. Roberto Bakker Meta-analysis Hedges g - comparisons with same placebo Oct 19