[R-meta] (Too) Many effect sizes for one single group

[Cátia Ferreira De Oliveira]

Dear Lukasz,

Thank you for your response! I have also opted for aggregating the results
to check if that study came out as an influential/outlier study and it did
not, would this also be a good approach?
I will also run the models in the way suggested. Thank you again.

Best wishes,

Catia

On Fri, 7 Jan 2022 at 15:38, Lukasz Stasielowicz <
lukasz.stasielowicz using uni-osnabrueck.de> wrote:

> Dear Catia,
>
> under certain circumstances it could be a valid concern.
> Fortunately, one can test it directly. One could conduct a sensitivity
> analysis to examine the impact in your specific case: Do the results
> (mean effect, standard error etc.) change much if you exclude certain
> effect sizes?
>
> Example:
> Scenario 1: All effects are considered
> Scenario 2: The study with "too many" effect sizes is excluded
> Scenario 3: Only one or several effect sizes from the problematic study
> are considered, e.g. by using the sample() function and choosing a
> certain number of effects randomly. One could also repeat this procedure
> to check the influence of the selection procedure.
>
> If the estimates differ only slightly across the analyses then you could
> proceed with the original idea (including all effects). You could
> mention in the report that this decision is based on some sensitivity
> analyses that you've conducted.
>
>
> Best wishes
> Lukasz
> --
> Lukasz Stasielowicz
> Osnabrück University
> Institute for Psychology
> Research methods, psychological assessment, and evaluation
> Seminarstraße 20
> 49074 Osnabrück (Germany)
>
> Am 06.01.2022 um 12:00 schrieb r-sig-meta-analysis-request using r-project.org:
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> >     1. (Too) Many effect sizes for one single group
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> > ----------------------------------------------------------------------
> >
> > Message: 1
> > Date: Wed, 5 Jan 2022 19:32:29 +0000
> > From: =?UTF-8?Q?C=C3=A1tia_Ferreira_De_Oliveira?= <cmfo500 using york.ac.uk>
> > To: R meta <r-sig-meta-analysis using r-project.org>,  "Viechtbauer,
> >       Wolfgang (SP)" <wolfgang.viechtbauer using maastrichtuniversity.nl>
> > Subject: [R-meta] (Too) Many effect sizes for one single group
> > Message-ID:
> >       <
> CACw+TffviaNdFERh3Pp361ZJVO2F11WG7S2G8WdWcONiHcusFg using mail.gmail.com>
> > Content-Type: text/plain; charset="utf-8"
> >
> > Dear Wolfgang,
> >
> > I hope you had a lovely start to the year.
> > I am sorry for starting the year with questions, but I just wanted to
> check
> > whether there is any drawback from including a lot of effect sizes from a
> > single paper when most labs contributed to the meta-analysis with just
> one
> > or two effect sizes? This resulted in a dataset where half of the effect
> > sizes come from multiple experiments run by the same group. The nested
> > nature of the data and dependency of some effect sizes coming from the
> same
> > participants is acknowledged in the model.
> >
> > Thank you!
> >
> > Catia
> >
>
>

-- 
Cátia Margarida Ferreira de Oliveira
Psychology PhD Student
Department of Psychology, Room A105
University of York, YO10 5DD
Twitter: @CatiaMOliveira
pronouns: she, her

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