Estimates the variation matrix with robust methods.
Usage
variation(x, robust = TRUE)
Arguments
x
data frame or matrix with positive entries
robust
if FALSE, standard measures are used.
Value
The (robust) variation matrix.
Details
The variation matrix is estimated for a given compositional data set.
Instead of using the classical standard deviations the
mad is used when parameter robust is set to TRUE.
References
Aitchison, J. (1986) The Statistical Analysis of
Compositional Data Monographs on Statistics and Applied Probability.
Chapman \& Hall Ltd., London (UK). 416p.