Hi Stephane, thank you for this very useful information.
As for the global test, the tutorial of Benoit Gendreau-Berthiaume (as linked in my mail) does start the analysis with anova.cca on a RDA fitting all available dbMEM before doing variable selection. Does this satisfy the requirement of a global test? Cheers, Tim Am 06.06.2019 um 17:03 schrieb Stéphane Dray: > Hi, > > we introduced a new function mem.select in adespatial (that used > forward.sel) based on the work by Bauman et al > (https://onlinelibrary.wiley.com/doi/abs/10.1111/ecog.03380) > Basically, we showed that you should use a global test before > performing forward selection (this step is suggested by Blanchet et al > but rarely performed in ecological studies). > > Cheers > > > Le 06/06/2019 à 16:41, Tim Richter-Heitmann a écrit : >> Dear Irene, >> >> i found this tutorial very useful: >> >> https://sites.ualberta.ca/~ahamann/teaching/renr690/Lab9.pdf >> >> You basically do a forward selection (forward.sel() from packfor >> package) using the adjusted R-square (RsquareAdj() from vegan package). >> >> Hope this helps, Tim >> >> Am 06.06.2019 um 16:34 schrieb Irene Adamo: >>> Dear all, >>> >>> I am trying to run a variaion partitioning in using the varpart >>> function in >>> vegan. I would like to include the geographic coordinates as >>> explanatory >>> variables so I calculated the principle coordinates of neighbour >>> matrices. >>> Now I would like to perform a selection of the significant spatial >>> eigenvectors but I don`t know how to do it in R. Could anybody help me? >>> >>> data(mite.xy) >>> pcnm1 <- pcnm(dist(mite.xy)) >>> >>> then I get the pcnm vectors and I would like to select only the >>> significant ones. >>> >>> Thanks a lot! >>> >>> [[alternative HTML version deleted]] >>> >>> _______________________________________________ >>> R-sig-ecology mailing list >>> R-sig-ecology@r-project.org >>> https://stat.ethz.ch/mailman/listinfo/r-sig-ecology >> > -- Dr. Tim Richter-Heitmann University of Bremen Microbial Ecophysiology Group (AG Friedrich) FB02 - Biologie/Chemie Leobener Straße (NW2 A2130) D-28359 Bremen Tel.: 0049(0)421 218-63062 Fax: 0049(0)421 218-63069 [[alternative HTML version deleted]] _______________________________________________ R-sig-ecology mailing list R-sig-ecology@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-ecology
