[R-meta] Meta-analysis with observational and experimental studies

[PARRA DE LA ROSA, KAREN]

Dear Michael,

Many thanks for your reply. I am interested in multiple groups in each
trial. What you are suggesting is to use the raw mean per group and
then transform it into r (which is the metric I am using) instead of
calculating the contrast between groups?

Best,

Karen

El dom, 5 nov 2023 a las 12:49, Michael Dewey
(<lists using dewey.myzen.co.uk>) escribió:
>
> Dear Karen
>
> I will leave it to others to coment on model choice but one thing which
> occurs to me is that if you just use one arm in a trial does that not
> convert it into an observational study?
>
> Michael
>
> On 05/11/2023 10:15, PARRA DE LA ROSA, KAREN via R-sig-meta-analysis wrote:
> > Hi everyone,
> >
> > I am conducting a systematic review and meta-analysis on the impact of
> > different types of appearance-focused social media activities on body
> > image. I wanted to test a novel categorization of these types of
> > social media activities so we can better understand if the shared
> > characteristics of different activities could explain their
> > effect/relationship with body image. On the other hand, I am also
> > interested in having an estimate per activity. The dataset has 130
> > studies, half observational (cross-sectional, longitudinal, experience
> > sampling), and half experimental studies. The vast majority of them
> > contribute more than one effect size because of different activities
> > and multiple outcomes. This is my first meta-analysis and also my
> > first time using R so I have many questions regarding how to specify
> > the model.
> >
> > I have read that observational and experimental research cannot be
> > synthesized in the same meta-analysis as they are answering different
> > questions. So I was running two different analyses for each type of
> > study. As for observational studies I fitted with metafor and
> > clubsandwich a correlated and hierarchical model with robust variance
> > estimation to account for the multiple dependencies among effect
> > sizes. So effect sizes are nested within studies. However, the problem
> > I am facing is with experimental studies. I have organized them in a
> > different file with the mean, sd, and n per treatment condition. I am
> > not interested in the comparison with control groups, rather I am
> > interested in understanding if, for instance, exposure to body ideals
> > is better/worse than posting this type of content. I have several
> > comparisons like the one in the example. I thought that a network
> > meta-analysis in netmeta could be the best solution but as far as I
> > know, this package does not allow for moderator analysis, so could not
> > be able to run a subgroup analysis with the categories of activities.
> > I do not know what the best approach to analyze this data. Also, I
> > have never seen in my field a paper with two different types of
> > meta-analysis: a three-level for observational and an NMA for
> > experimental.
> >
> > Hope someone on the mailing list could help me with some of this doubt.
> >
> > Thanks in advance for your help and guidance.
> >
> > Best,
> >
> > Karen
> >
> > _______________________________________________
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> >
>
> --
> Michael

-- 
Karen Parra De La Rosa
PhD student at Pompeu Fabra University
Researching social media and body image
Barcelona, Spain