[R-meta] (partial) eta squared

[Viechtbauer, Wolfgang (SP)]

Dear Antonia,

in principle, you could meta-analyze eta^2 values, but there are several issues to consider:

1) The sampling distribution of eta^2 isn't normal. So, one would first have to explore what kind of transformation would be appropriate for eta^2 values to normalize their sampling distribution.

2) I do not know off the top of my head an equation for the sampling variance of eta^2 values.

3) eta^2 isn't a directional effect size measure. Two eta^2 values of the same magnitude could imply entirely opposite findings. So, one could question the usefulness of aggregating eta^2 values in the first place.

Best,
Wolfgang

-----Original Message-----
From: R-sig-meta-analysis [mailto:r-sig-meta-analysis-bounces using r-project.org] On Behalf Of Antonia Sudkaemper
Sent: Friday, 03 August, 2018 12:33
To: r-sig-meta-analysis using r-project.org
Subject: [R-meta] (partial) eta squared

Hello fellow meta-analysis colleagues,

I have recently started using metafor and am still exploring. Currently, I am
working on a mini meta-analysis of three studies I ran myself. In recent
psychology journal I have seen the use of (partial) eta squared as an
indicator of effect size. I was wondering if I can use the rma.uni command
to run a meta-analysis on (partial) eta squared? And if so, which error
(vi/sei) indicator would I use with it?

Hope someone can help!

All the best, Antonia

-- 
Antonia Sudkämper
PhD Candidate in Organizational Psychology/University of Exeter
www.antoniasudkaemper.com
a.sudkaemper using gmail.com