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gld.moments

Calculate moments of the FKML type of the generalised lambda distribution for given parameter values


Description

Calculates the mean, variance, skewness ratio and kurtosis ratio of the generalised lambda distribution for given parameter values.

Usage

gld.moments(par,type="fkml",ratios=TRUE)

Arguments

par

A vector of length 4, giving the parameters of the generalised lambda distribution, consisting of; lambda 1 location parameter lambda 2 - scale parameter lambda 3 - first shape parameter lambda 4 - second shape parameter

type

choose the type of generalised lambda distribution. Currently gld.moments only supports fkml which uses Freimer, Kollia, Mudholkar, and Lin (1988) (default).

ratios

Logical. TRUE to give moment ratios for skewness and kurtosis, FALSE to give the third and fourth central moments instead.

Details

The FKML type of the generalised lambda distribution was introduced by Freimer et al (1988) who gave expressions for the moments. In the limit, as the shape parameters (lambda 3 and lambda 4) go to zero, the distribution is defined using limit results. The moments in these limiting cases were given by van Staden (2013). This function calculates the first 4 moments.

See pages 96–97 of van Staden (2013) for the full expressions for these moments.

Value

A vector containing the first four moments of the FKML type generalized lambda. If ratio is true, the vector contains the mean, variance, skewness ratio and kurtosis ratio. If ratio is false, the vector contains the mean, variance, third central moment and fourth central moment.

Author(s)

Sigbert Klinke

Paul van Staden

References

Au-Yeung, Susanna W. M. (2003) Finding Probability Distributions From Moments, Masters thesis, Imperial College of Science, Technology and Medicine (University of London), Department of Computing https://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.106.6130&rep=rep1&type=pdf

Freimer, M., Kollia, G., Mudholkar, G. S., & Lin, C. T. (1988), A study of the generalized tukey lambda family, Communications in Statistics - Theory and Methods 17, 3547–3567.

Lakhany, Asif and Mausser, Helmut (2000) Estimating the parameters of the generalized lambda distribution, Algo Research Quarterly, 3(3):47–58

van Staden, Paul J. (2013) Modeling of generalized families of probability distributions inthe quantile statistical universe, PhD thesis, University of Pretoria. https://repository.up.ac.za/handle/2263/40265

See Also

Examples

gld.moments(c(0,1.463551,0.1349124,0.1349124))
gld.moments(c(0,1.813799,0,0))
gld.moments(c(0,1,0,3))

gld

Estimation and Use of the Generalised (Tukey) Lambda Distribution

v2.6.2
GPL (>= 2)
Authors
Robert King <Robert.King@newcastle.edu.au>, Benjamin Dean <Benjamin.Dean@uon.edu.au>, Sigbert Klinke, Paul van Staden
Initial release
2020-01-07

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