Bibliometric indicators for authors
Bibliometric indicators for authors
H-index
The H-index is an indicator of the individual performance for researchers, but it is also applicable to research groups and institutions.
Definition of the Hirsch Index
A scientist has an h-index if h of his/her Np works have at least h citations each, and the remaining (Np-h) works have at most h-1 citations each.
By H-index, sometimes known as the Hirsch index, we referred to an index proposed in 2005 by Jorge E. Hirsch of the University of California, San Diego: it is useful to quantify the productivity and impact of scientists, based on both the number of their publications and the number of citations received. According to the definition, a scientist has an index of n if they have published at least n papers, each of which has been cited at least n times. An author with an H-index of 15 has published at least 15 papers, each with at least 15 citations (from Wikipedia).
The advantage of using the h-index is that it combines an evaluation of both quantity (number of papers) and quality (impact, or citations of these documents) (Glänzel, 2006).
An author cannot have a high h-index without publishing a significant number of documents, but these documents must be cited by other academics in order to contribute to the h-index.
N.B. The H-index of an author may vary depending on the bibliographic database or search engine used: the bibliographic and temporal coverage my differ, as well as potential errors related to cases of homonymy: always cite the database used for the calculation of the H-index.
Moreover, the H-index should always be used in reference to the entire work of an author, not to a limited time frame.
The H-index can be calculated based on data collected from:
Scopus - accessible only within the university network
Web of Science - accessible only within the university network
Google Scholar - free
The H-index calculated on the bibliographic database Scopus considers only articles published from 1996 in all journals indexed in Elsevier's archive (usually requiring payment).
It can be reached from the author registry or from the citation tracker.
Searching for a specific author will retrieve a summary sheet with the author's personal data, their research and an H-graph showing articles and citations over a period of time.
"Citation report" on Web of Science
Using the Author Finder option) one can check the H-index by clicking on the column on the right.
"Publish or Perish" o "scholar index" on Google Scholar
Google Scholar does not automatically retrieve the H-index, but numerous tools can search through its archive.
Publish or Perish (PoP di A.Harzing): free and reliable software
Scholar index: fast and friendly web interface. It uses Google Scholar, but only calculates works from 2000 onwards and does not easily remove homonyms.
QuadSearch - MetaSearch Engine: It calculates the H-index for a specific author
Scholarometer: developed by Indiana University, it has extensions for Firefox and Chrome browsers. It is a collaborative tool that uses user tags.
This is a software that calculates of the H-index considering Google Scholar data as a source. Use search characters the results can be improved:
to search for an author exact name use quotation marks
to eliminate articles with the same title innsert the name of the author in the reserved field of search.
Source: PubblicoErgoSum
About the H-Index
We suggest you to read: "Reflections on the h-index / A.Harzing"
To summarize :
It is not an good indicatero for "young researchers" as their papers have not yet had the time to receive citations. More than anything this is valid for the social sciences where it usually takes at around 5 years to accumulate a significant number of citations
it varies depending on the field of studies. The h-index are usually higher in the Natural Sciences rather than in the Social and Human Sciences since for the Natural Science a higher numeber of shorter articles are published, whileSocial and Human Sciences the articles are fewer and longer (often books).
There is a risk of "self-citations" especially the papers written by many co-authors. Hirsch himself (2005), in this latter case, provides indications on how to normalize the H-index.
We recommend consulting the website Pubblico Ergo Sum
Issues calculating through Scopus:
A lot of cases of homonymy can be found in Scopus as well as or many errors of duplication of authors (sometimes depending on the affiliation). However, in the latter case they can be groupped and the H-index can be calculated cumulatively.
Issues calculating through Google Scholar:
Usually Google Scholar as a bibliographic archive tends to overstimate the results. We suggest you to read.
Jacsó, Testing the Calculation of a Realistic h-index in Google Scholar, Scopus, and Web of Science for F. W. Lancaster. Library Trends 56(4) 784-815.
Click here for more articles by P. Jacsó.
Issues calculating through Web of Science
The social sciences are less represented (Harzing, 2008).
Moreover, sometimes "phantom citations" can be found: these are citations that appear on the database but they are not really in the work that should cite them. See Garcia-Perez, 2010 for more information.
Proposed by Leo Egghe, it aims to improve the calculation of the H-index by giving greater weight to the most cited articles.
You can consulti:
L. Egghe, Theory and practice of the g-index, Scientometrics, Vol. 69, No 1 (2006), pp. 131-152
It calculates the H-index by giving less weight to older articles: this overcomes the problem of the lower number of citations for "young researchers" is overcome (see issue n. 1).
This standardisation is the one considered by ANVUR for the national scientific certification.
It adds an age-related weight to each item mentioned, giving less emphasis to older works.
So in Publish or Perish the attribution ofan age-related weight is normalized by a factor 4: the citations for an article published in the current year are counted 4 times; the citations of an article published 4 years ago count for 1 (4/4); the citations of an article published six years ago weigh 4/6 [1].
There are further variants of the H-index (individual H-index etc.), so we recommended you to consult Bibliometric indicators (de Robbio) or the Publish or Perish User Manual.
[1] Antonis Sidiropoulos, Dimitrios Katsaros, and Yannis Manolopoulos, Generalized h-index for disclosing latent facts in citation networks, arXiv:cs.DL/0607066 v1 13 Jul 2006.
Guide for the calculation in Scopus - created by Universty of Urbino's Settore Bibliotecario d'Ateneo
Further readings:
Gorraiz-Schloegl, 2008 J. Gorraiz, C. Schloegl, A bibliometric analysis of pharmacology and pharmacy journals: Scopus versus Web of Science, in Journal of Information Science 34 (5) (2008) 715-725
Bar-Ilan, 2008 J. Bar-Ilan, Which h-index? - A comparison of WoS, Scopus and Google Scholar, Scientometrics 74 (2) (2008), pp. 257-271.
Frandsen and Nicolaisen, 2008 T.F. Frandsen and J. Nicolaisen, Intradisciplinary differences in database coverage and the consequences for bibliometric research, Journal of the American Society for Information Science and Technology 59 (10) (2008), pp. 1570-1581.
Jacso, 2008a P. Jacso, Testing the calculation of a realistic h-index in Google Scholar, Scopus, and Web of Science for F. W. Lancaster, Library Trends 56 (4) (2008), pp.784-815.