Estimation of the value of alpha via the profile log-likelihood {Compositional}

Estimation of the value of \alpha via the alfa profile log-likelihood

Description

Estimation of the value of \alpha via the alfa profile log-likelihood.

Usage

alfa.profile(x, a = seq(-1, 1, by = 0.01))

Arguments

x

A matrix with the compositional data. Zero values are not allowed.

a

A grid of values of \alpha.

Details

For every value of \alpha the normal likelihood (see the refernece) is computed. At the end, the plot of the values is constructed.

Value

A list including:

res

The chosen value of \alpha, the corresponding log-likelihood value and the log-likelihood when \alpha=0.

ci

An asympotic 95% confidence interval computed from the log-likelihood ratio test.

Author(s)

Michail Tsagris.

R implementation and documentation: Michail Tsagris [e-mail] and Giorgos Athineou <[e-mail]>.

References

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.tune, alfa, alfainv

Examples

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