Message-ID: <3cf0158d-b894-d0b0-445b-ddf652a162ce@dewey.myzen.co.uk>
Date: 2020-06-19T12:50:42Z
From: Michael Dewey
Subject: [R-meta] Testing multicollinearity between categorical predictors
In-Reply-To: <CAAnf+jSbHFif2KZgTCykFRAztD-v34QVKms47Gjs84n-+AN4zA@mail.gmail.com>
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.
> _______________________________________________________
>
> *Prof. Dr. Rafael Rios Moura*
>
> *sciencia amabilis *
> Coordenador de Pesquisa e do NEPEE/CNPq
> Laborat?rio de Ecologia e Zoologia (LEZ)
> UEMG - Unidade Ituiutaba
>
> ORCID: http://orcid.org/0000-0002-7911-4734
> Curr?culo 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 Ci?ncia: https://www.youtube.com/channel/UCu2186wIJKji22ai8tvlUfg
> <http://orcid.org/0000-0002-7911-4734>
>
>
> Em sex., 19 de jun. de 2020 ?s 05:40, Viechtbauer, Wolfgang (SP) <
> wolfgang.viechtbauer at 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 at gmail.com]
>>> Sent: Wednesday, 17 June, 2020 2:28
>>> To: Viechtbauer, Wolfgang (SP); r-sig-meta-analysis at 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
>>> Laborat?rio de Ecologia e Zoologia (LEZ)
>>> UEMG - Unidade Ituiutaba
>>>
>>> ORCID: http://orcid.org/0000-0002-7911-4734
>>> Curr?culo Lattes: http://lattes.cnpq.br/4264357546465157
>>> Research Gate: https://www.researchgate.net/profile/Rafael_Rios_Moura2
>>> Rios de Ci?ncia: https://www.youtube.com/channel/UCu2186wIJKji22ai8tvlUfg
>>
>
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>
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>
--
Michael
http://www.dewey.myzen.co.uk/home.html