• Is (relatively) easy to determine
  • Considers both productivity (publications) and resonance (citations)
  • Is robust; this means that the evaluation focuses on the stable mean


  • Is a rather rough measure; someone who publishes little but is outstanding may receive the same H-index as someone who publishes a lot but is rarely cited
  • Is age-dependent (older scientists are generally preferred)
  • Not suitable for cross-discipline comparisons

The H-index is an bibliometric indicator that attempts to evaluate the scientific lifetime achievement of a person. Publications and citations are taken into account in combination. An H-index of "7", for example, indicates that a person has published 7 publications, each of which has been cited at least 7 times.

The H-index (also called Hirsch factor or H-number) was developed in 2005 by physicist Jorge E. Hirsch at the University of California.

Although the limitations of this indicator quickly became clear, it gained increasing importance. In the databases Web of Science and Scopus, it is now calculated automatically. This only works well if the author and his or her publications can be clearly identified. This is sometimes extremely difficult. It should also be noted that only citations from the Web of Science or Scopus are taken into account. In this case, a large part may be lost, which in turn could lead to a distortion of the results.

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