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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