On the correction of the h-index for career length

We describe mathematically the age-independent version of the h-index, defined by Abt (Scientometrics 91(3):863–868, 2012) and explain when this indicator is constant with age. We compare this index with the one where not the h-index is divided by career length but where all citation numbers are divided by career length and where we then calculate the new h-index. Both mathematical models are compared. A variant of this second method is by calculating the h-index of the citation data, divided by article age. Examples are given.