Compositional (version 5.5)

Estimation of the value of alpha via the profile log-likelihood: 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 \(\alpha\).

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.

Details

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

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

# NOT RUN {
x <- as.matrix(iris[, 1:4])
x <- x / rowSums(x)
alfa.tune(x)
alfa.profile(x)
# }