Themes

H-index

What is this about?

The h-index, introduced by Jorge Hirsch in 2005, is a metric that conveys both the productivity and citation impact of an individual researcher (1). If a researcher has a h-index of 5 then the researcher has 5 publications with 5 or more citations. A h-index of 75 means that there are 75 publications with 75 or more citations. It thus becomes progressively more difficult to increase one’s h-index, and h-indices are exponentially distributed among scientists.

Why is this important?

The h-index was partially introduced as an improvement over simply counting the quantity of a researcher’s publications. A researcher with 10 publications may have a higher h-index than a researcher with 100 publications.

However, as with any other metric, it is possible to ‘game’, or artificially increase, one’s h-index. Some well-established strategies include:

  • Self-citation (cf. Italian scientists increase self-citations in response to promotion policy (2)
  • Honorary authorship (putting a distinguished researcher on an authorship list often increases citation)
  • Publishing on ‘hot topics’
  • Writing review papers (often more cited than original studies)

Any aspect of citation bias can be taken advantage of for improving h-index.

For whom is this important?

Researchers, Universities, Funders, Journal publishers

What are the best practices?

For best practices, see authorship page, and citation bias page.

References

1. Hirsch JE. An index to quantify an individual's scientific research output. Proceedings of the National academy of Sciences 2005;102(46):16569-16572.

2. Chawla DS. Italian scientists increase self-citations in response to promotion policy. 2018; Available at: https://www.natureindex.com/news-blog/italian-scientists-increase-self-citations-in-response-to-promotion-policy. Accessed 29 May, 2019.