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

[Bert Gunter]

**If** I understand correctly, this is because of correlation in
effects due to non-independence between males and females in the data.
As this is primarily a statistical, not an R programming, issue, I
suggest you post on a statistics list like stats.stackexchange.com.
Better yet, talk with a local statistical resource.

If I misunderstand, correction would be appreciated.

Cheers,
Bert


Bert Gunter

"The trouble with having an open mind is that people keep coming along
and sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )


On Sat, Dec 12, 2015 at 7:35 AM, Carlijn . <wibbeltjec at hotmail.com> wrote:
>
>
> 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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