Message-ID: <9e6352ef-26e9-28ab-5a79-27784710d892@imbi.uni-freiburg.de>
Date: 2019-09-30T17:31:24Z
From: Guido Schwarzer
Subject: [R-meta] Duplicating the results of the metabin() function
In-Reply-To: <CALJFG-S6HwbtQki7_px546Mjk8dhEQOYTN0iCWAaCprws_=zpg@mail.gmail.com>
Hi Sam,
The discrepancy in your calculations can be explained as follows.
By default, R function metabin() uses the Mantel-Haenszel method
(argument 'method') under the fixed effect model. Accordingly, the fixed
effect weights in 'w.fixed' come from the Mantel-Haenszel method.
However, in order to calculate Cochran's Q, the fixed effect weights
from the inverse variance method are used (which are different from the
Mantel-Haenszel weights).
You could use the following assignment in your code to calculate Q by hand:
weights.fixed <- 1 / result$seTE^2
or
weights.fixed <- update(result, method = "Inverse")$w.fixed
Best wishes, Guido
P.S. 'OR <- result$TE' should actually be 'lnOR <- result$TE' as
metabin() stores the log odds ratio instead of the odds ratio.
--
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 at 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