Compositional (version 1.2)

alfa.profile: 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.

See Also

alfa.tune, alfa, alfainv

Examples

library(MASS)
x <- iris[, 1:4]
alfa.tune(x)
alfa.profile(x)