Ramajeyam Tharshan https:/orcid.org/0000-0002-6112-2517 , Pushpakanthie Wijekoon http://orcid.org/0000-0003-4242-1017

© Ramajeyam Tharshan, Pushpakanthie Wijekoon. Article available under the CC BY-SA 4.0 licence


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The Poisson-Modification of Quasi Lindley (PMQL) distribution is a newly introduced mixed Poisson distribution for over-dispersed count data. The aim of this article is to introduce the Zero-modified PMQL (ZMPMQL) distribution as an alternative to the PMQL distribution in order to accommodate zero inflation/deflation. The method of obtaining the ZMPMQL distribution jointly with some of its important properties, namely the probability mass and distribution functions, mean, variance, index of dispersion, and quantile function are presented. Furthermore, some of its special cases are discussed. The maximum likelihood (ML) estimation method is used for the unknown parameter estimation. A simulation study is conducted in order to evaluate the asymptotic theory of the ML estimation method and to show the superiority of the ML method over the method of moments estimation. The applicability of the introduced distribution is illustrated by using a real-world data set.


over-dispersion, mixed Poisson distribution, PMQL distribution, zero modification, maximum likelihood estimation


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