-----Original Message-----
From: Filippo Gambarota [mailto:filippo.gambarota at gmail.com]
Sent: Monday, 03 January, 2022 17:11
To: Viechtbauer, Wolfgang (SP)
Cc: R meta
Subject: Re: [R-meta] fixed-effect multivariate model interpretation
Thank you?Wolfgang!
So my related question is how this residual heterogeneity is estimated in order
to compute the Q statistic? Because if the model is still estimating and testing
the presence of heterogeneity, from a multivariate model I would have expected
one residual heterogeneity term for each outcome (the same as I have one tau per
outcome if I fit the random-effect version).
On Mon, 3 Jan 2022 at 16:50, Viechtbauer, Wolfgang (SP)
<wolfgang.viechtbauer at maastrichtuniversity.nl> wrote:
Hi Filippo,
You can *assume* that there is no residual heterogeneity, but there may be. That
is what the test of residual heterogeneity is testing here (whether your
assumption is correct or not).
Best,
Wolfgang
-----Original Message-----
From: R-sig-meta-analysis [mailto:r-sig-meta-analysis-bounces at r-project.org] On
Behalf Of Filippo Gambarota
Sent: Monday, 03 January, 2022 16:42
To: R meta
Subject: [R-meta] fixed-effect multivariate model interpretation
Hello!
I'm fitting for the first time a multivariate fixed-effect model using
metafor. The code is:
```
rma.mv(yi, V, mods = ~ 0 + outcome, data = data, test = "t")
```
Where V is the block variance-covariance matrix created with vcalc()
that represents the covariance between different outcome levels within
each study. The outcome is a factor that represents different effect
sizes measured on the same participants within a study.
The model as expected did not estimate tau for each outcome and test
all coefficients (each outcome mean with this parametrization) against
0 (both the omnibus test and each beta). My question is about the
*residual heterogeneity* parameter and the associated Q test. Under
this model, I should have assumed that there is no heterogeneity
within each outcome level so I'm not sure how to interpret the
residual heterogeneity in this case.
Thank you!
Filippo
--
Filippo Gambarota
PhD Student - University of Padova
Department of Developmental and Social Psychology
Website: filippogambarota.netlify.app
Research Group: Colab? ?Psicostat