a.est: Estimation of the value of alpha in the folded model

In Compositional: Compositional Data Analysis

Estimation of the value of \alpha in the folded model

Description

Estimation of the value of \alpha in the folded model.

Usage

a.est(x)

Arguments

x	A matrix with the compositional data. No zero vaues are allowed.

Details

This is a function for choosing or estimating the value of \alpha in the folded model (Tsagris and Stewart, 2020).

Value

A list including:

runtime	The runtime of the algorithm.
best	The estimated optimal \alpha of the folded model.
loglik	The maximimised log-likelihood of the folded model.
p	The estimated probability inside the simplex of the folded model.
mu	The estimated mean vector of the folded model.
su	The estimated covariance matrix of the folded model.

Author(s)

Michail Tsagris.

R implementation and documentation: Michail Tsagris [e-mail].

References

Tsagris M. and Stewart C. (2022). A Review of Flexible Transformations for Modeling Compositional Data. In Advances and Innovations in Statistics and Data Science, pp. 225–234. https://link.springer.com/chapter/10.1007/978-3-031-08329-7_10

Tsagris M. and Stewart C. (2020). A folded model for compositional data analysis. Australian and New Zealand Journal of Statistics, 62(2): 249-277. https://arxiv.org/pdf/1802.07330.pdf

Tsagris M.T., Preston S. and Wood A.T.A. (2011). A data-based power transformation for compositional data. In Proceedings of the 4th Compositional Data Analysis Workshop, Girona, Spain. https://arxiv.org/pdf/1106.1451.pdf

See Also

alfa.profile, alfa, alfainv, alpha.mle

Examples

x <- as.matrix(iris[, 1:4])
x <- x / rowSums(x)
alfa.tune(x)
a.est(x)

Compositional documentation built on June 22, 2025, 5:08 p.m.