vegandevs/vegan — pull request #64 by jarioksa (2014-10-28 12:59:33+00:00)
Title: Add ordiareatests for ordihull and ordiellipse

This PR suggests adding permutation test to study the sizes of ordination hulls or ellipses. `ordiareatest` relates to `betadisper` like `envfit` relates to `adonis`, and studies the dispersion of points in ordination space. The alternative hypothesis is that the fitted hulls or ellipses have smaller area than randomized ones. It appeared that I could use this function in a collaborative research project. However, the function is not quite standard, because there is no overall significance statistic, but each shape is analysed separately. Here is an example output of PCA (`rda`) of `dune` data:
```R
Permutation test for the size of ordination hulls
Alternative hypothesis: observed area is smaller than random hull

Permutation: free
Number of permutations: 999

Area 5% 50% Pr(