On the time dependence of the h-index

The time dependence of the h-index is analyzed by considering the average behavior of h as a function of the academic age AA for about 1400 Italian physicists, with career lengths spanning from 3 to 46 years. The individual h-index is strongly correlated with the square root of the total citations NC: h≈0.53NC. For academic ages ranging from 12 to 24 years, the distribution of the time scaled index h/AA is approximately time-independent and it is well described by the Gompertz function. The time scaled index h/AA has an average approximately equal to 3.8 and a standard deviation approximately equal to 1.6. Finally, the time scaled index h/AA appears to be strongly correlated with the contemporary h-index hc.

► The individual h  -index is strongly correlated with the number of individual citations. ► The quantity h/AA appears to be strongly correlated with the contemporary h  -index. ► h/AA grows linearly, stays at a plateau value, drops to a lower plateau as function of AA. ► Other group averaged indicators show similar trends as function of AA. ► To assess scientists active for more than 10 years, it appears reasonable to compare h/AA to the plateau values.