h-index

The h-index is an author-level metric that measures both the productivity and citation impact of the publications, initially used for an individual scientist or scholar. The h-index correlates with success indicators such as winning the Nobel Prize, being accepted for research fellowships and holding positions at top universities.^[1] The index is based on the set of the scientist's most cited papers and the number of citations that they have received in other publications. The index has more recently been applied to the productivity and impact of a scholarly journal^[2] as well as a group of scientists, such as a department or university or country.^[3] The index was suggested in 2005 by Jorge E. Hirsch, a physicist at UC San Diego, as a tool for determining theoretical physicists' relative quality^[4] and is sometimes called the Hirsch index or Hirsch number.

Hirsch intended the h-index to address the main disadvantages of other bibliometric indicators. The total number of papers metric does not account for the quality of scientific publications. The total number of citations metric, on the other hand, can be heavily affected by participation in a single publication of major influence (for instance, methodological papers proposing successful new techniques, methods or approximations, which can generate a large number of citations). The index works best when comparing scholars working in the same field, since citation conventions differ widely among different fields.^[5]

The h-index is intended to measure simultaneously the quality and quantity of scientific output. The Kendall's correlation of h-index with scientific awards in physics was found at 34 percent in 2010 and zero percent in 2019.^[6]