Total variability
Total variability.
totvar(x, a = 0)
x |
A numerical matrix with the compositional data. |
a |
The value of the power transformation, it has to be between -1 and 1. If zero values are present it has to be greater than 0. If α=0 the centred log-ratio transformation is used. |
The α-transformation is applied and the sum of the variances of the transformed variables is calculated. This is the total variability. Aitchison (1986) used the centred log-ratio transformation, but we have extended it to cover more geometries, via the α-transformation.
The total variability of the data in a given geometry as dictated by the value of α.
Michail Tsagris
R implementation and documentation: Michail Tsagris mtsagris@uoc.gr
Aitchison J. (1986). The statistical analysis of compositional data. Chapman \& Hall.
alfa, \ link{alfainv,} alfa.profile, alfa.tune
x <- as.matrix(iris[, 1:4]) x <- x / rowSums(x) totvar(x)
Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.