MLE of the folded model for a given value of α
MLE of the folded model for a given value of α.
alpha.mle(x, a) a.mle(a, x)
x |
A matrix with the compositional data. No zero vaues are allowed. |
a |
A value of α. |
This is a function for choosing or estimating the value of α in the folded model
(Tsagris and Stewart, 2020). It is called by a.est.
If "alpha.mle" is called, a list including:
iters |
The nubmer of iterations the EM algorithm required. |
loglik |
The maximimized 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. |
If "a.mle" is called, the log-likelihood is returned only.
Michail Tsagris
R implementation and documentation: Michail Tsagris mtsagris@uoc.gr
Tsagris Michail and Stewart Connie (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
x <- as.matrix(iris[, 1:4]) x <- x / rowSums(x) mod <- alfa.tune(x) mod alpha.mle(x, mod[1])
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