Theory, R functions & Examples
Section: Ordination analysis
vegan) - variable selection function, which is applicable with functions
cmdscale. Offers forward, backward and combined step-wise selection algorithm (specified by argument
direction). Comparison of variables is based on AIC criteria and P-values from Monte Carlo permutation test.
vegan) - similar to
ordistep, but based on R2adj, and implements three stopping stopping rules when selecting the variables: if R2adj of the selected model starts to decrease, or R2adj of global model (defined in
scope) is exceeded, or any remaining variable is not significant at predefined P-value. It can be used with
capscale. (Before, this function used to be limited to only
capscale, but recently vegan implements the permutation method of estimating adjusted R2 for CCA (Peres-Neto et al. 2006) into the function RsquareAdj, and since then the
ordir2stepfunction can handle also formula with
adespatial) - variable selection method, which is implicitly using RDA ordination, and offers only forward selection (not backward or step-wise). Contains stopping rules from Borcard et al. 2008, the same as
ordiR2step, but has different logic for setting of arguments. Eventually, however, it returns the same results as
ordiR2stepand could be favoured by rather easy use (no need to specify null and full models and the scope).