[R-meta] Accounting for baseline differences in meta-analysis
Dear Gladys If I understand this correctly in a randomised study you can analyse the post treatment values alone or take into account any baseline value you wish. You may get a more precise result if you adjust for baseline. Michael
On 02/02/2021 08:57, Gladys Barragan-Jason wrote:
Dear Gerta,
Thanks for your response. I also realized that most of the time papers
do not report the pre-treatment and/or the pre-control values. Sometimes
they just say that the values are not different but do not report
thoses, but more often they do not measure it at all.? Is there any way
to take this into account?...I am not sure about how to deal with
presence vs. absence of such values in the meta-analysis or whether this
just needs to be discussed as a potential limitation.
Thanks a lot for your response.
Gladys
Le?jeu. 28 janv. 2021 ??12:35, Dr. Gerta R?cker
<ruecker at imbi.uni-freiburg.de <mailto:ruecker at imbi.uni-freiburg.de>> a
?crit?:
Dear Gladys,
An obvious approach would be to take the post values (or,
equivalently, the change scores) as an outcome, and the baseline
values as a covariate in a metaregression model.
Best,
Gerta
Am 28.01.2021 um 10:49 schrieb Gladys Barragan-Jason:
Dear all,
I would like to know how to take the baseline difference into
account in meta-analysis of the impact of a treatment on
experimental data in which the baseline of the control group is
different from the baseline of the treatment.
For now, I am using the post- means and SD of the control and the
treatment group (and the rma.mv <http://rma.mv> function) and also
the pre-post values of the treatment group but I don't think this
is correct and I am not sure how to proceed.
Any advice?
Thanks a lot in advance.
Best regards,
Gladys
--
------------------------------------------
Gladys Barragan-Jason, PhD. ?Website
<https://sites.google.com/view/gladysbarraganjason/home>
Station d'Ecologie Th?orique et Exp?rimentale (SETE)
CNRS de Moulis
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