# Ordination (statistics)

The term ordinations many mathematical procedures are summarized which aim to graphically illustrate certain data in a coordinate system.

These are used for example in ecology and vegetation science, to compare different vegetation surveys and to clarify their differences along one or more gradient. To organize the data, it is first assumed that an n-dimensional space ( the number of dimensions corresponds to the example number of plant species found ). By means of mathematical methods, a so-called dimension reduction is performed so that the position of the data ( recording vegetation ) can be represented in a two - or three-dimensional coordinate system. The axes of the coordinate system gradients are supposed to represent (or combine several gradients, where, for example, water and nutrient content of the soil ) that explain as much of the variance. The environment variables can thereby be analyzed directly or indirectly concluded from the occurrence of plant species.

Examples of ordination procedures are:

- CA - Correspondence Analysis, Correspondence Analysis
- CCA - Canonical Correspondence Analysis, Canonical Correspondence Analysis
- DCA - Detrended Correspondence Analysis
- PCA - Principal Component Analysis, Principal Component Analysis

## Swell

- Lyre, I. & K. Wesche (2007) Multivariate Statistics in Ecology: An Introduction. - Berlin ( Springer )
- Palmer, M. Ordination Methods for Ecologists.

- Multivariate Statistics