[R-meta] Question about rma(measure = "COR", ..)

[Guido Schwarzer]

Am 21.10.19 um 15:22 schrieb Jalynskij, Maria:

> [...]
> b) Or should I use rma(measure="ZCOR", ri = corr, ni = n, data = data), and conduct the main result back by myown at the end?
>
>
> In the second version the Trim and Fill method doesn't make any sense.

Dear Maria,

While one may question whether Trim and Fill is the best method to 
adjust for small study effects in meta-analysis, I do not understand why 
the method should make sense for untransformed correlations but not for 
Fisher z-transformed correlations.

Trim and Fill removes the most extreme studies (trim step), determines a 
symmetry axis and adds the extreme studies on the opposite side (fill 
step). This works both for untransformed and Fisher transformed 
correlations.

Best wishes, Guido

P.S. I would always prefer to meta-analyse Fisher transformed 
correlations as the meta-analysis of untransformed correlations could 
result in impossible confidence limits outside -1 and 1. Accordingly, 
the Fisher method is the default in /metacor()/ of R package *meta* 
(which automatically does the back-calculation for the user).

-- 
Dr. Guido Schwarzer
Institute of Medical Biometry and Statistics,
Faculty of Medicine and Medical Center - University of Freiburg

Postal address: Stefan-Meier-Str. 26, D-79104 Freiburg

Phone: +49/761/203-6668
Mail: sc using imbi.uni-freiburg.de
Homepage: http://www.imbi.uni-freiburg.de

ORCID iD: https://orcid.org/0000-0001-6214-9087
R-book: https://www.springer.com/gp/book/9783319214153


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