[R-meta] correct tau interpretation three-level meta-analysis

[Filippo Gambarota]

Thank you!
Sorry I used the word standard badly. With standard, I mean the usual
between-study heterogeneity that we estimate in a random-effect model.
Given that the `outcome` heterogeneity is the variability within each study
cluster (i.e. the variability around the true effect for each `study`), my
question is:
Do we interpret it as an average variability within each cluster among
clusters? Or we are assuming that each cluster has the same within-cluster
variability?
Thank you!

On Mon, 5 Jul 2021 at 17:04, Viechtbauer, Wolfgang (SP) <
wolfgang.viechtbauer using maastrichtuniversity.nl> wrote:

> Dear Filippo,
>
> The variance component corresponding to 'study' is the amount of
> heterogeneity in the average true effects of the various studies (i.e.,
> studies with multiple outcomes have an average true effect). The variance
> component corresponding 'outcome' is the amount of heterogeneity in the
> true effects around those average true effects of the studies.
>
> So, I would say that neither is really the standard heterogeneity, but
> that also depends on what exactly you mean by that.
>
> Best,
> Wolfgang
>
> >-----Original Message-----
> >From: R-sig-meta-analysis [mailto:
> r-sig-meta-analysis-bounces using r-project.org] On
> >Behalf Of Filippo Gambarota
> >Sent: Sunday, 04 July, 2021 12:36
> >To: r-sig-meta-analysis using r-project.org
> >Subject: [R-meta] correct tau interpretation three-level meta-analysis
> >
> >Hi,
> >I'm conducting a meta-analysis using a three-level model because I
> >have multiple effects within the same study. My model is something
> >like this:
> >
> >```
> >rma.mv(yi, vi, random = ~1|study/outcome)
> >```
> >My question is simply how to correctly interpret tau at the outcome
> >level. The tau at the study level is basically the standard
> >heterogeneity. The tau at the outcome level is the average variability
> >within a cluster (study)?
> >Thanks
> >
> >--
> >Filippo Gambarota
> >PhD Student - University of Padova
> >Department of Developmental and Social Psychology
> >Website: filippogambarota.netlify.app
> >Research Group: Colab   Psicostat
>


-- 
*Filippo Gambarota*
PhD Student - University of Padova
Department of Developmental and Social Psychology
Website: filippogambarota.netlify.app
Research Group: Colab <http://colab.psy.unipd.it/>   Psicostat
<https://psicostat.dpss.psy.unipd.it/>

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