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.