[R-meta] Compiling different design in the same met-analysis

[Gladys Barragan-Jason]

Yes, it does make sense.
Thanks a lot Gerta.
Best,
Gladys

Le mar. 4 mai 2021 à 11:25, Gerta Ruecker <ruecker using imbi.uni-freiburg.de> a
écrit :

> Hi Gladys,
>
> Note that separate meta-analyses is not the same as subgroup analysis. If
> you do a subgroup analysis (in the Cochrane sense), you have design as a
> moderator and obtain a treatment-design interaction test, which you don't
> get if conducing separate analyses. Therefore I would prefer to present all
> in one.
>
> Best,
>
> Gerta
> Am 04.05.2021 um 11:17 schrieb Gladys Barragan-Jason:
>
> Hi all,
> Thanks a lot for your responses.
> Actually, I did not specify it before but I am using the rma.mv function
> since I can have several estimates from several studies of the same lab
> (random=~1|lab/study/estid). Following your recommendations, I checked
> whether the type of design had a significant effect on effect sizes and
> actually it didn't except for one specific type of intervention in which I
> do not have that much data:  3 papers for each design containing 7 and 4
> effect sizes respectively. In this case, meta-analysis of overall estimates
> is non-significant while when computing them separately, one is significant
> (control vs. treatment groups) while the other is not (pre- vs. post
> treatment).
> I do think that would make sense to present the overall meta-analysis as
> well as the two designs separately ? In any case, we would need more data
> to conclude for sure.
> Best,
> Gladys
>
> Le lun. 3 mai 2021 à 20:18, Viechtbauer, Wolfgang (SP) <
> wolfgang.viechtbauer using maastrichtuniversity.nl> a écrit :
>
>> Agree, but I also want to point to this:
>>
>> https://www.metafor-project.org/doku.php/tips:computing_adjusted_effects
>>
>> It discusses the concept of computing adjusted effects, which may be what
>> you are looking for, Gladys. However, as noted at the end, some may
>> question the usefulness and interpretability of such an estimate.
>>
>> Best,
>> Wolfgang
>>
>> >-----Original Message-----
>> >From: R-sig-meta-analysis [mailto:
>> r-sig-meta-analysis-bounces using r-project.org] On
>> >Behalf Of Dr. Gerta Rücker
>> >Sent: Monday, 03 May, 2021 20:09
>> >To: Gladys Barragan-Jason
>> >Cc: R meta
>> >Subject: Re: [R-meta] Compiling different design in the same met-analysis
>> >
>> >Hi Gladys,
>> >
>> >You may pool all effects in a meta-analysis, using "design" as a
>> >moderator. In meta-analysis, this is called a subgroup analysis (for
>> >example by Cochrane). You then get both within-subgroup effects and a
>> >pooled effect, and also a test of treatment--design interaction, that
>> >says whether the treatment effect is different between designs. Thus you
>> >have all what you are interested in. However, in your interpretation you
>> >have to account for the different character of the studies: In a
>> >two-group parallel design, if it is randomized (you did not mention
>> >whether it is), you can expect an unbiased estimate of the treatment
>> >effect. In a pre-post design, you must expect all kinds of biases (to
>> >mention only regression to the mean) and also, as Michael said,
>> >different variation. Therefore you have to interpret results with
>> caution.
>> >
>> >Best, Gerta
>> >
>> >Am 03.05.2021 um 19:42 schrieb Gladys Barragan-Jason:
>> >> Hi Gerta and Michael,
>> >> I am not sure to understand. I am not saying the the effect size are
>> >> different. They are comparable but of course differ in term of ci
>> >> since the number of studies, participants are different. I would like
>> >> to know whether we can make obtain an overall effect size while
>> >> controlling for design. So maybe the answer is no.
>> >> Thanks
>> >> Gladys
>>
>
>
> --
>
> ------------------------------------------
>
> Gladys Barragan-Jason, PhD.  Website
> <https://sites.google.com/view/gladysbarraganjason/home>
>
> Station d'Ecologie Théorique et Expérimentale (SETE)
>
> CNRS de Moulis
>
> [image: image.png][image: image.png]
>
>
>
>
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> --
>
> Dr. rer. nat. Gerta Rücker, Dipl.-Math.
>
> Institute of Medical Biometry and Statistics,
> Faculty of Medicine and Medical Center - University of Freiburg
>
> Stefan-Meier-Str. 26, D-79104 Freiburg, Germany
>
> Phone:    +49/761/203-6673
> Fax:      +49/761/203-6680
> Mail:     ruecker using imbi.uni-freiburg.de
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>
>

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