Research Article
The Exponentiated Half-Logistic Family of Distributions:
Properties and Applications
Gauss M. Cordeiro,
1
Morad Alizadeh,
2
and Edwin M. M. Ortega
3
1
Departamento de Estat´ ıstica, Universidade Federal de Pernambuco, 50740-540 Recife, PE, Brazil
2
Department of Statistics, Ferdowsi University, Mashhad 9177948974, Iran
3
Departamento de Ciˆ encias Exatas, Universidade de S˜ ao Paulo, 13418-900 Piracicaba, SP, Brazil
Correspondence should be addressed to Gauss M. Cordeiro; gausscordeiro@uol.com.br
Received 3 September 2013; Accepted 5 December 2013; Published 13 March 2014
Academic Editor: Ricardas Zitikis
Copyright © 2014 Gauss M. Cordeiro et al. his 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 study some mathematical properties of a new generator of continuous distributions with two extra parameters called the
exponentiated half-logistic family. We present some special models. We investigate the shapes of the density and hazard rate
function. We derive explicit expressions for the ordinary and incomplete moments, quantile and generating functions, probability
weighted moments, Bonferroni and Lorenz curves, Shannon and R´ enyi entropies, and order statistics, which hold for any baseline
model. We introduce two bivariate extensions of this family. We discuss the estimation of the model parameters by maximum
likelihood and demonstrate the potentiality of the new family by means of two real data sets.
1. Introduction
he use of new generators of continuous distributions from
classic distributions has become very common in recent
years. One example is the beta-generated family of distri-
butions proposed by Eugene et al. [4]. Another example
is the gamma-generated family of distributions deined by
Zografos and Balakrishnan [5]. Based on a baseline continu-
ous distribution () with survival function () and density
(), their families are deined by the cumulative distribution
function (cdf) and probability density function (pdf) (for
∈ R):
()=
1
Γ()
∫
− log[ (;)]
0
−1
−
,
()=
1
Γ()
{− log [ (;)]}
−1
(;),
(1)
respectively, where Γ() = ∫
∞
0
−1
−
is the gamma
function.
Based on Zografos and Balakrishnan’s [5] paper, we
replace the gamma distribution by the exponentiated half-
logistic (“EHL” for short) distribution to deine a new family
of continuous distributions by the cdf:
()=∫
− log[1−(;)]
0
2
−
[1−
−
]
−1
[1+
−
]
+1
={
1−[1−(;)]
1+[1−(;)]
}
,
(2)
where (;) is the baseline cdf depending on a parameter
vector and >0 and >0 are two additional shape
parameters. For any continuous distribution, the EHL-
distribution is deined by the cdf (2). Equation (2) is a wider
family of continuous distributions and includes some special
models as those listed in Table 1.
Hindawi Publishing Corporation
Journal of Probability and Statistics
Volume 2014, Article ID 864396, 21 pages
http://dx.doi.org/10.1155/2014/864396