Hi, I know that A*B = A+B+A:B, but in this case, i.e. doing an adonis2 and specifying by="terms" will only do the test for the interaction, not the main effects. If one chooses by="terms", you will get a test for the main effects and the interaction, but than the order of factors matters.
Best regards Ellen On Tue, 16 Oct 2018 at 12:23, Torsten Hauffe <torsten.hau...@gmail.com> wrote: > "adonis2(speciesdataset~A*B, by="margin") but then only the effect of the > interaction is tested." > > This is not entirely correct. > adonis2(speciesdataset~A:B, by="margin") would test the interaction > alone. ~A*B unfolds to ~A+B+A:B > > On Tue, 16 Oct 2018 at 11:51, Ellen Pape <ellen.p...@gmail.com> wrote: > >> Hi all, >> >> 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 >> https://stat.ethz.ch/mailman/listinfo/r-sig-ecology >> > [[alternative HTML version deleted]] _______________________________________________ R-sig-ecology mailing list R-sig-ecology@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-ecology
