Message-ID: <e04b9ac1-7be4-d1be-18ca-116080bbed9e@imbi.uni-freiburg.de>
Date: 2019-10-07T12:16:28Z
From: Guido Schwarzer
Subject: [R-meta] Calculating SMD from posttest only - is this possible?
In-Reply-To: <CAKDq9_OTq6NaD4SUuWer+d=BSJc=RMfyz3NWAVZX1w2Cr+HRhw-5103@mail.gmail.com>
Hi Roberto,
Just to add to the responses by Wolfgang and James.
The Cochrane Handbook warns against combining SMDs based on change
scores (pre-post comparisons) and post-test comparisons (see
https://training.cochrane.org/handbook/current/chapter-10#section-10-5-2).
The reason is that the standard deviation used in the denominator of the
SMD is different for change scores and post-tests.
Best wishes, Guido
--
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