[R-meta] Testing multicollinearity between categorical predictors
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 [[alternative HTML version deleted]] _______________________________________________ R-sig-meta-analysis mailing list R-sig-meta-analysis at r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-meta-analysis