Research Article
The Exponentiated Gumbel Type-2 Distribution:
Properties and Application
I. E. Okorie,
1
A. C. Akpanta,
2
and J. Ohakwe
3
1
School of Mathematics, University of Manchester, Manchester M13 9PL, UK
2
Department of Statistics, Abia State University, PMB 2000, Uturu, Abia State, Nigeria
3
Department of Mathematics & Statistics, Faculty of Sciences, Federal University, Otuoke, PMB 126, Yenagoa, Bayelsa, Nigeria
Correspondence should be addressed to I. E. Okorie; idika.okorie@postgrad.manchester.ac.uk
Received 17 May 2016; Accepted 10 July 2016
Academic Editor: Niansheng Tang
Copyright © 2016 I. E. Okorie et al. Tis is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
We introduce a generalized version of the standard Gumble type-2 distribution. Te new lifetime distribution is called the
Exponentiated Gumbel (EG) type-2 distribution. Te EG type-2 distribution has three nested submodels, namely, the Gumbel type-
2 distribution, the Exponentiated Fr´ echet (EF) distribution, and the Fr´ echet distribution. Some statistical and reliability properties
of the new distribution were given and the method of maximum likelihood estimates was proposed for estimating the model
parameters. Te usefulness and fexibility of the Exponentiated Gumbel (EG) type-2 distribution were illustrated with a real lifetime
data set. Results based on the log-likelihood and information statistics values showed that the EG type-2 distribution provides a
better ft to the data than the other competing distributions. Also, the consistency of the parameters of the new distribution was
demonstrated through a simulation study. Te EG type-2 distribution is therefore recommended for efective modelling of lifetime
data.
1. Introduction
Te Gumbel distribution, also known as the type-1 extreme
value distribution, has received signifcant research attention,
over the years particularly, in extreme value analysis of
extreme events. For a review of the recent developments
and applications of the Gumbel distribution, see Pinheiro
and Ferrari [1]. Tere is no question that, before now, the
Gumbel type-2 distribution is not popularly used in statistical
modelling and the reason may not be far from its lack of fts in
data modelling. Generally, standard probability distributions
are well known for their lack of fts in modelling complex
data sets. On this note, users of this distributions across
various felds in general and statistics and mathematics in
particular have been fantastically motivated to developing
sophisticated probability distributions from the existing ones.
Exponentiated distributions have been introduced to solve
the problem of lack of fts that is commonly encountered
when using the standard probability distributions for mod-
elling complex data sets. Results from this advancement
have frequently been proven more reasonable than the
one based on the standard distributions. Exponentiating
distributions are indeed a powerful technique in statistical
modelling that ofers an efective way of introducing an
additional shape parameter to the standard distribution to
achieve robustness and fexibility. Tis method of generaliz-
ing probability distributions is traceable to the work of Gupta
et al. [2] who introduced the exponentiated exponential
(EE) distribution as a generalized form of the standard
exponential distribution by simply raising the cumulative
density function (cdf) to a positive constant power. Ever
since the introduction of the EE distribution, exponentiated
distributions have achieved reasonable feats in modelling
data sets from various complex phenomena. A good number
of standard probability distributions have their correspond-
ing exponentiated versions. Gupta et al. [2] introduced the
Exponentiated Weibull distribution as a generalization of
the standard Weibull distribution. Nadarajah and Kotz [3]
modifed the method by Gupta et al. [2] and introduced
the Exponentiated Fr´ echet distribution as a generalization of
the standard Fr´ echet distribution. Using the same method
in Nadarajah and Kotz [3], Nadarajah [4] introduced the
Hindawi Publishing Corporation
International Journal of Mathematics and Mathematical Sciences
Volume 2016, Article ID 5898356, 10 pages
http://dx.doi.org/10.1155/2016/5898356