El 16/10/2018 a las 12:09, Ellen Pape escribió: > Hi, > > Yes, but is there no way of testing for the main effects and > interaction simultaneously?
In general, this is "not allowed", to say it with your words. > > I also thought of first testing the interaction: > adonis2(speciesdataset~ A *** B, by="margin") , and then - if the > interaction is not significant- testing for the main effects by > adonis2(speciesdataset~ A *+* B, by="margin") . Is this "allowed"? This is analogous to, e.g., an ANCOVA, isn't it? Therefore it makes quite sense. > > Thanks, > Ellen > > On Tue, 16 Oct 2018 at 12:01, Marcelino De La Cruz Rot > <marcelino.delac...@urjc.es <mailto:marcelino.delac...@urjc.es>> wrote: > > El 16/10/2018 a las 11:51, Ellen Pape escribió: > > Hi all, > > > Maybe adonis2(speciesdataset~ A + B, by="margin") ? > > > > > I don't know whether this is the correct mailing group to > address this > > question: > > > > I would like to perform a 2-way permanova analysis in R (using > adonis in > > vegan). By default you are performing sequential tests > (by="terms"), so > > when you have 2 or more factors, the order of these factors matter. > > However, since I wanted to circumvent this, I chose for the option > > by="margin" (adonis2(speciesdataset~A*B, by="margin")) but then > only the > > effect of the interaction is tested. On the "help page" of > anova. cca it > > says: "if you select by="margin" -> the current function only > evaluates > > marginal terms. It will, for instance, ignore main effects that are > > included in interaction terms." > > > > > > My question now is: can I somehow get the main effects tested > anyhow, when > > the interaction term is not significant? > > > > Thanks, > > Ellen > > > > [[alternative HTML version deleted]] > > > > _______________________________________________ > > R-sig-ecology mailing list > > R-sig-ecology@r-project.org <mailto:R-sig-ecology@r-project.org> > > https://stat.ethz.ch/mailman/listinfo/r-sig-ecology > > . > > > > -- > Marcelino de la Cruz Rot > Depto. de Biología y Geología > Física y Química Inorgánica > Universidad Rey Juan Carlos > Móstoles España > -- Marcelino de la Cruz Rot Depto. de Biología y Geología Física y Química Inorgánica Universidad Rey Juan Carlos Móstoles España _______________________________________________ R-sig-ecology mailing list R-sig-ecology@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-ecology
