extra.parameter: Tool that supports the estimation of the extra parameter.

Description

extra.parameter is used to plot a graph of the behaviour of the overall goodness-of-fit statistic and \(-2\textsf{L}(\hat{\theta})\) versus the extra parameter \(\zeta\) in the interval/region defined by the arguments lower and upper. These graphs may be used to choosing the extra parameter value.

Usage

extra.parameter(object, lower, upper, grid)

Arguments

object: an object of the class ssym. This object is returned by the call to ssym.l(), ssym.nl() or ssym.l2()
lower: lower limit(s) of the interest interval/region for the extra parameter.
upper: upper limit(s) of the interest interval/region for the extra parameter.
grid: Number of values of the extra parameter where the overall goodness-of-fit statistic and \(-2\textsf{L}(\hat{\theta})\) are evaluated.

Author

Luis Hernando Vanegas <hvanegasp@gmail.com> and Gilberto A. Paula

References

Vanegas, L.H. and Paula, G.A. (2015b) Log-symmetric distributions: statistical properties and parameter estimation. Brazilian Journal of Probability and Statistics (to appear)

Examples

Run this code

###################################################################################
############### Textures of snacks Data - a log-Student-t model  #################
###################################################################################
#data("Snacks", package="ssym")
#fit <- extra.parameter(log(texture) ~ type + ncs(week) | type, data=Snacks,
#        family='Student', xi=10)
#summary(fit)
#
############################ Extra parameter ###########################
#extra.parameter(fit,5,50)

###################################################################################
################## Biaxial Fatigue Data - a Birnbaum-Saunders model   #############
###################################################################################
#data("Biaxial", package="ssym")
#fit <- ssym.nl(log(Life) ~ b1*Work^b2, start=c(b1=16, b2=-0.25),
#                data=Biaxial, family='Sinh-normal', xi=1.54)
#summary(fit)
#
########################### Extra parameter ###########################
#extra.parameter(fit,1.3,1.8)

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