16.3.4 Contemporary h-index

The Hc-index corrects for the recentness of the citations, with recent citations carrying more weight. It was proposed by Antonis Sidiropoulos, Dimitrios Katsaros, and Yannis Manolopoulos in their paper Generalized h-index for disclosing latent facts in citation networks, arXiv:cs.DL/0607066 v1 13 Jul 2006. It adds an age-related weighting to each cited article, giving (by default; this depends on the parameterization) less weight to older articles.

The weighting is parameterized; the Publish or Perish implementation uses gamma=4 and delta=1, like the authors did for their experiments. This means that for an article published during the current year, its citations account four times. For an article published 4 years ago, its citations account only one time. For an article published 6 years ago, its citations account 4/6 times, and so on.

As the number of years that our academics have been active varies from 16 to 42, we would expect differences between them to be smaller for the Hc-index than for the h-index. Figure 11 shows that this is indeed the case. Our pharmacologist has been active for 42 and has the highest h-index. However, much of high highly-cited work was published a long time ago and his Hc-index is less than half of his regular h-index.

In contrast, the Business and Education academic have been active only 16 and 28 years and have recently published work that is highly cited. Hence their Hc-indices are nearly 90% of their h-indices. Differences between the Sciences and the Social Sciences and Humanities are smaller for the Hc-index (17 versus 16) than for the h-index (28 versus 21).

Figure 11: H-index compared with the Contemporary index for academics in different disciplines