Probaby the difference is the adjustment: varpart() uses adjusted R-squared, but rda() output reports unadjusted proportions. RsqureAdj() function gives both.
Cheers, jari Oksanen ________________________________________ From: R-sig-ecology <r-sig-ecology-boun...@r-project.org> on behalf of Tim Richter-Heitmann <trich...@uni-bremen.de> Sent: 02 November 2015 15:58 To: r-sig-ecology@r-project.org Subject: [R-sig-eco] Differences between total constrained inertia (rda) and variance explained (varpart()) in vegan Dear list, when i perform RDA on a species set constrained with a set of predictors, which i have tested for their relevance by forward selection, i get values for inertia: Inertia Proportion Rank Total 0.12626 1.00000 Constrained 0.05493 0.43507 11 Unconstrained 0.07133 0.56493 48 So, the amount of explained inertia is 0.05493/0.1262 or roughly 43%. I am now grouping the same predictors into three groups (soil, vegetation, space) and perform varpart() on them, i get a total variance (sum of all explained variance) explained of only 30%. This has been consistent for me in a variety of datasets. Can somebody explain to me the difference? Thank you! -- Tim Richter-Heitmann (M.Sc.) PhD Candidate International Max-Planck Research School for Marine Microbiology 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 _______________________________________________ R-sig-ecology mailing list R-sig-ecology@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-ecology _______________________________________________ R-sig-ecology mailing list R-sig-ecology@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-ecology