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Abstract
Abd El-Bar 2018, ‘An extended Gompertz-Makeham distribution with application to lifetime data’, Communication in Statistics – Simulation and Computation, 47, 2454–2475) introduced a four-parameter extension of the Gompertz-Makeham distribution, and derived some statistical and reliability measures like moments, moment generating function, conditional moments, among many others. In this short communication, we show that some of the closed-form expressions derived by the author cannot be used since they depend on power series expansions which are not convergent. We provide, therefore, simple and correct expressions to compute such properties.
Additional information
Funding
Fredy Castellares gratefully acknowledges the financial support from FAPEMIG (Belo Horizonte/MG, Brazil). Artur Lemonte gratefully acknowledges the financial support of the Brazilian agency CNPq (grant 301808/2016–3). The authors would like to thank an anonymous referee for the comments.