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

[Michael Dewey]

If you include a moderator you do not get an overall effect because by 
including it you are effectively saying there is no single overall effect.

On 03/05/2021 12:24, Gladys Barragan-Jason wrote:
> Hi Michael,
> Thanks a lot for your quick response. Here are answers and other 
> questions below.
> 
> Le lun. 3 mai 2021 à 12:41, Michael Dewey <lists using dewey.myzen.co.uk 
> <mailto:lists using dewey.myzen.co.uk>> a écrit :
> 
>     Dear Gladys
> 
>     Comments in-line
> 
>     On 03/05/2021 08:13, Gladys Barragan-Jason wrote:
>      > Dear all,
>      >
>      > I am doing a meta-analysis on experimental data on the impact on
>      > several behavioral interventions including both *pre-post studies*
>      > (measurement of a trait before and after the intervention) *and
>     control
>      > vs. treatment studies *(measurement after a control intervention vs.
>      > measurement after the intervention).
> 
>     So the first design just has one group which is measured twice and the
>     second design has two parallel groups which are each measured once?
> 
> 
> Exactly!
> 
> 
>      > I am interested in the effect size of each type of intervention on a
>      > specific trait that is common to all studies.
>      >
>      > I would like to know whether it is correct to compile all studies
>     from
>      > one type of intervention (whatever the type of comparisons:
>     pre-pot and
>      > control vs. treatment group together) with pre- and control being as
>      > control and post and treatment being as treatment.
>      >
> 
>     I do not think that is going to work well. Although the two designs
>     could be considered as estimating the same effect their variability
>     should be very different since in design 1 you have reduced the effect
>     of individual variability. If you do include both designs in one
>     analysis I would have thought it mandatory to include a moderator with
>     two levels for design.
> 
> This makes sense. When I do this, I then obtain two effect sizes (one 
> for each design); (in having mods=~design-1). Do you know how I can get 
> the overall effect size?
> 
> 
>      > I have a second question about how to thank the
>      > r-sig-meta-analysis using r-project.org
>     <mailto:r-sig-meta-analysis using r-project.org>
>      > <mailto:r-sig-meta-analysis using r-project.org
>     <mailto:r-sig-meta-analysis using r-project.org>> list for all their help
>      > (acknowledgements in a paper).
> 
>     I would have thought the URL
>     https://stat.ethz.ch/mailman/listinfo/r-sig-meta-analysis//
>     <https://stat.ethz.ch/mailman/listinfo/r-sig-meta-analysis//>
>     was better. How to do this will also depend on custom and practice in
>     your scientific discipline, some journals in mine require people who
>     are
>     acknowledged to give their consent.
> 
> 
> Ok! Thanks a lot!
> 
> Best,
> Gladys
> 
> 
>     Michael
> 
>      >
>      > Thanks a lot for your help!
>      >
>      > Have a great day,
>      >
>      > Gladys
>      >
>      > --
>      >
>      > ------------------------------------------
>      >
>      > Gladys Barragan-Jason, PhD. ____ Website
>      > <https://sites.google.com/view/gladysbarraganjason/home
>     <https://sites.google.com/view/gladysbarraganjason/home>>
>      >
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>     -- 
>     Michael
>     http://www.dewey.myzen.co.uk/home.html
>     <http://www.dewey.myzen.co.uk/home.html>
> 
> 
> 
> -- 
> 
> ------------------------------------------
> 
> Gladys Barragan-Jason, PhD. ____ Website 
> <https://sites.google.com/view/gladysbarraganjason/home>
> 
> Station d'Ecologie Théorique et Expérimentale (SETE)____
> 
> CNRS de Moulis____
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> 
> 

-- 
Michael
http://www.dewey.myzen.co.uk/home.html