[R-meta] Testing multicollinearity between categorical predictors

[Rafael Rios]

Thank you very much, Wolfgang. Do you have a reference supporting this
approach? It will be very helpful.

Best wishes,

Rafael.
_______________________________________________________

*Prof. Dr. Rafael Rios Moura*

*scientia amabilis *
Coordenador de Pesquisa e do NEPEE/CNPq
Laboratório de Ecologia e Zoologia (LEZ)
UEMG - Unidade Ituiutaba

ORCID: http://orcid.org/0000-0002-7911-4734
Currículo Lattes: http://lattes.cnpq.br/4264357546465157
<http://orcid.org/0000-0002-7911-4734>
<http://lattes.cnpq.br/4264357546465157>
<http://lattes.cnpq.br/4264357546465157>Research Gate:
https://www.researchgate.net/profile/Rafael_Rios_Moura2
<http://orcid.org/0000-0002-7911-4734>
Rios de Ciência: https://www.youtube.com/channel/UCu2186wIJKji22ai8tvlUfg
<http://orcid.org/0000-0002-7911-4734>


Em sex., 19 de jun. de 2020 às 12:03, Viechtbauer, Wolfgang (SP) <
wolfgang.viechtbauer using maastrichtuniversity.nl> escreveu:

> In that case, you can just use vif(). The 'generalized VIF' is only
> relevant when a factor variable has more than two levels and one wants to
> compute a VIF that pertains to the whole factor, not just each of the
> individual dummy variable. But if the factor only has two levels, then
> there is only one dummy variable, so this is the same as GVIF.
>
> Best,
> Wolfgang
>
> >-----Original Message-----
> >From: Rafael Rios [mailto:biorafaelrm using gmail.com]
> >Sent: Friday, 19 June, 2020 16:35
> >To: Viechtbauer, Wolfgang (SP)
> >Cc: r-sig-meta-analysis using r-project.org
> >Subject: Re: [R-meta] Testing multicollinearity between categorical
> >predictors
> >
> >Dear Wolfgang,
> >
> >Yes, it is. Yes and no for each moderator. I am also evaluating their
> >interaction.
> >
> >All the best,
> >
> >Rafael.
> >
> >Em sex., 19 de jun. de 2020 às 10:12, Viechtbauer, Wolfgang (SP)
> ><wolfgang.viechtbauer using maastrichtuniversity.nl> escreveu:
> >I am not sure I fully understand. Are you saying that the two moderators
> >have two levels each?
> >
> >Best,
> >Wolfgang
> >
> >>-----Original Message-----
> >>From: Rafael Rios [mailto:biorafaelrm using gmail.com]
> >>Sent: Friday, 19 June, 2020 15:02
> >>To: Michael Dewey
> >>Cc: Viechtbauer, Wolfgang (SP); r-sig-meta-analysis using r-project.org
> >>Subject: Re: [R-meta] Testing multicollinearity between categorical
> >>predictors
> >>
> >>Dear Michael,
> >>
> >>Thank you for the reply. I am evaluating the biases arising from pooling
> >>samples from different populations and periods on the average effect
> size.
> >>Therefore, I included both pooling practices, and their interaction as
> >>moderators. Each practice has two levels (yes and no).
> >>
> >>Best wishes,
> >>
> >>Rafael.
> >>
> >>Em sex., 19 de jun. de 2020 às 09:50, Michael Dewey
> >><lists using dewey.myzen.co.uk> escreveu:
> >>Dear Rafael
> >>
> >>It is hard to answer here because we do not know what scientific problem
> >>the referee thinks he or she has spotted which would be solved by such a
> >>test. Being of a cynical world view I suspect neither does the referee
> >>and this is a conditioned reflex like Pavlov's dog salivating at the
> bell.
> >>
> >>Are the two moderators of scientific interest to you or are you
> >>including them so you can say that there is still residual heterogeneity
> >>even after you did your best to explain it? In the latter case I would
> >>suggest collinearity is irrelevant.
> >>
> >>Michael
> >>
> >>On 19/06/2020 13:36, Rafael Rios wrote:
> >>> Dear Wolfgang,
> >>>
> >>> Thank you for the replay. I also thought about using VIF to evaluate
> >>> multicollinearity, but there is a lot of criticism about the
> >applicability
> >>> of VIF for categorical predictors. There is a variation called GVIF.
> >>> However, since the meta-analysis changes categorical predictors to
> dummy
> >>> variables, I could not use it in R. I am not sure whether this is the
> >best
> >>> approach. Do you not other methods to evaluate or avoid potential
> >>> multicollinearity among categorical moderators?
> >>>
> >>> Best wishes,
> >>>
> >>> Rafael.
> >>>
> >>> Em sex., 19 de jun. de 2020 às 05:40, Viechtbauer, Wolfgang (SP) <
> >>> wolfgang.viechtbauer using maastrichtuniversity.nl> escreveu:
> >>>
> >>>> Dear Rafael,
> >>>>
> >>>> I don't know what "testing" for multicollinearity would entail. One
> >could
> >>>> examine the variance inflation factors with vif(). What VIF values are
> >>>> considered "large" is debatable though.
> >>>>
> >>>> Best,
> >>>> Wolfgang
> >>>>
> >>>>> -----Original Message-----
> >>>>> From: Rafael Rios [mailto:biorafaelrm using gmail.com]
> >>>>> Sent: Wednesday, 17 June, 2020 2:28
> >>>>> To: Viechtbauer, Wolfgang (SP); r-sig-meta-analysis using r-project.org
> >>>>> Subject: Testing multicollinearity between categorical predictors
> >>>>>
> >>>>> Dear Wolfgang and All,
> >>>>>
> >>>>> Is there a good method for testing multicollinearity between
> >categorical
> >>>>> predictors in meta-regression? I ran a mixed-effects MLMA using two
> >>>>> categorical predictors and their interaction as moderators, but a
> >>Referee
> >>>>> requested a test of multicollinearity. I did not find a good approach
> >to
> >>>>> solve this problem. Thank you in advance.
> >>>>>
> >>>>> Best wishes,
> >>>>> _______________________________________________________
> >>>>>
> >>>>> Prof. Dr. Rafael Rios Moura
> >>>>> sciencia amabilis
> >>>>> Coordenador de Pesquisa e do NEPEE/CNPq
> >>>>> Laboratório de Ecologia e Zoologia (LEZ)
> >>>>> UEMG - Unidade Ituiutaba
> >>>>>
> >>>>> ORCID: http://orcid.org/0000-0002-7911-4734
> >>>>> Currículo Lattes: http://lattes.cnpq.br/4264357546465157
> >>>>> Research Gate:
> https://www.researchgate.net/profile/Rafael_Rios_Moura2
> >>>>> Rios de Ciência:
> >https://www.youtube.com/channel/UCu2186wIJKji22ai8tvlUfg
>

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