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en:forward_sel_r
Section: Ordination analysis
Variable selection (constrained ordination)
R functions
ordistep(libraryvegan) - forward selection function applicable with functionsrda,ccaorcmdscale. Comparison of variables is based on AIC criteria and P-values from Monte Carlo permutation test.ordiR2step(libraryvegan) - similar to previous, but based on R2adj, and implements three stopping criteria: selection of variables will stop if R2adj of the selected model starts to degrees, or R2adj of global model (defined inscopeis exceeded, or any remaining variable is not significant at predefined P-value. It can be used withrda,ccaorcapscale1).forward.sel(libraryadespatial) - forward selection method usingrdaonly, and containing stopping rules from Borcard et al. 2008. Has different logic for setting of arguments than the two functions above, but basically returns the same results asordiR2step.
1)
ordir2step used to be limited to only rda and capscale before; recently, vegan implements the permutation method of estimating adjuster R2 for cca (Peres-Neto et al. 2006) into the function RsquareAdj, and since that time the ordir2step function can handle also formula with cca function.en/forward_sel_r.txt · Last modified: 2019/04/06 00:30 by David Zelený
