Can apply to: Authors who have published journal articles that have been cited in other scholarly publications
Metric definition: An author-level metric calculated from the count of citations to an author’s, or group of authors, publications.
Metric calculation: In his 2005 paper proposing the h-index, Hirsch describes the measure thusly: “A scientist has index h if h of his or her Np papers have at least h citations each and the other (Np – h) papers have fewer than ≤ h citations each.” For example, an author with an h-index of 6 has at least six journal articles that have each been cited at least six times each.
Data sources: Citation data used to calculate the h-index can be retrieved from Google Scholar, Scopus, Web of Science, or any other citation index that includes author- and article-level citation information.
Appropriate use cases: The h-index can be used as evidence of the scholarly influence of an author’s, or group of authors’, body of work. It is best used in conjunction with other metrics. Use of the h-index for groups occurs infrequently in practice.
Limitations: Many limitations to the h-index have been identified by bibliometrics experts. The h-index varies by discipline due to varying norms of publishing speed and quantity. Since it does not take into account the longevity of a scholar’s career, it benefits more experienced scholars over early-career individuals. The h-index is unable to differentiate between active and inactive scientists. It also fails to distinguish between publications which have had sustained impact over decades and those that may be ‘trendy’, receiving a burst of citations over a few years. The h-index is also relatively insensitive to highly cited papers. Many have attempted to fix the h-index’s weaknesses with various computational models that, for example, reward highly-cited papers, correct for career length, rank authors’ papers against other papers published in the same year and source, or count just the average citations of the most high-impact “core” of an author’s work. However, none of these improvements upon the h-index have been as widely adopted as the h-index itself.
Inappropriate use cases: The h-index should not be used as a sole metric of scholarly impact, nor should it be used as a direct measure of quality. The h-index should not be used to rank authors who are in different disciplines or those at different stages of their careers.
Transparency: The formula for calculating the h-index is openly available. See https://en.wikipedia.org/wiki/H-index.
Timeframe: The h-index can be calculated for any author or for any subset of an author’s, or group of authors’, publications over any time period.
Portions of this guide borrow from “Four reasons to stop caring so much about the h-index” by Stacy Konkiel and are reused here under a CC-BY license.