alfa.profile: Estimation of the value of alpha via the alfa profile...

Description Usage Arguments Details Value Author(s) References See Also Examples

View source: R/alfa.profile.R

Description

Estimation of the value of α via the alfa profile log-likelihood.

Usage

1
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 α.

Details

For every value of α 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 α, the corresponding log-likelihood value and the log-likelihood when α=0.

ci

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

Author(s)

Michail Tsagris

R implementation and documentation: Michail Tsagris <[email protected]> and Giorgos Athineou <[email protected]>

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

1
2
3
4
x <- as.matrix(iris[, 1:4])
x <- x / rowSums(x)
alfa.tune(x)
alfa.profile(x)

Example output

  best alpha  max log-lik log-lik at 0 
   0.7117536 1038.8853754  997.9317859 
$result
       alfa max.log.lik    log.lik0 
     0.7100   1040.3901    997.9318 

$ci
 2.5% 97.5% 
 0.58  0.84 

Compositional documentation built on June 4, 2018, 5:04 p.m.