The h-index was developed by J.E. Hirsch.
The h-index is based on a list of publications ranked in descending order by the times cited. The value of H is equal to the number of papers (N) in the list that have N or more citations. The h-index is calculated by the number of publications and the number of citations received. For example, an h index of 20 means there are 20 items, that have 20 citations or more.
Sources
Scopus is one of the most comprehensive database with coverage of more than 22,000 journal titles and many options for narrow down search results by keywords, years, affiliation and more. The database is used as a citation index tool and for citation analysis.
In Scopus, the h-index is dynamic and it is recalculated in real-time whenever you view it.
The h-index includes citations from expanded book coverage.
Web of Science is a multi-disciplinary database which besides its large scope and coverage is also used for citation indexing and analysis as standard in academic institutions worldwide.
In Web of Science, the h-index is automatically calculated from the indexed publications in the database, which includes scholarly articles, conference proceedings, and other types of academic work.
It is updated in real-time as new articles and citations are added into the database.
Considerations
Average H-Index depends on collection policy of the source.
Value for the H-index depends on source’s content and coverage.
WOS
- Citation data only for the records indexed by database.
- Limited number of journals.
- European bias.
- Calculates the H-index of an author from 1965 – current.
- Limited number of journals in non-English languages.
- Clear results from scholarly journals.
- “In press” articles are not indexed because of editorial policy.
- Only in their final form.
- Self-citations exclusion option.
- Access via subscription.
SCOPUS
Citation data only for the records indexed by database.
More content (about 22,000 journals) than in WOS (about 12,000 journals).
- American bias.
- Calculates the H-index of an author from 1996 – current.
- Scopus Cited References Expansion Program ensures cited references going back to 1970 will be added to pre-1996 Scopus content in the fourth quarter of 2014.
- Limited number of journals in non-English languages.
- Clear results from scholarly journals.
- One version of a paper in results.
- “In press” articles are included.
- Self-citations exclusion option.
- Access via subscription.
GOOGLE SCHOLAR
- Scholar’s work may be published in journals not covered by WOS and Scopus.
- Larger number of journals than in WOS and Scopus *not all scholarly journals are indexed in Google Scholar.
- Larger number of publications in non-English languages than in WOS and Scopus.
- Value of H-index may vary because of additional irrelevant citations results from non-scholarly citations (records from unknown sources and informal material).
- Not all of journals are of the same quality as those found in the Web of Science or Scopus.
- In some cases Scholar indexes preprint and journal version of a paper and provides in the results the sum of the two counts, so citations are spread over the duplicates.
- Provides an H-index only for researchers who created a user profile for themselves.
- Counts self-citations.
- Freely accessibly from the internet.
CITESEERX
- CiteSeerX focuses primarily on the literature in computer and information science.
- Uses ACI (Autonomous citation indexing) to automatically extract citations and create a citation index.
- Computes citation statistics and related documents for all articles cited in the database, not just the indexed articles.
The optimal methodology to value H-index for researcher is to consult Google Scholar in addition to Web of Science or Scopus.
Different disciplines have different standards for citation.
It is unfair to compare h-index of researchers working in different disciplines:
- Disciplines that use more references per paper are expected to have a higher index.
- Researchers in specialist subjects may have a lower h-index than those in more popular or currently topical areas.
- Coverage in different disciplines is not the same in different sources.
- Journals indexed in the WOS cover mainly the core disciplines in the natural sciences.
- Journals indexed in the WOS and Scopus do not sufficiently cover fields such as computer science.
- Journals indexed in the Web of Science do not sufficiently cover the field of engineering science either.
- Google Scholar’s coverage in disciplines such as Biology, Chemistry, and Physics is lower compared to Web of Science (WOS) or Scopus. However, Google Scholar provides broader coverage for the four social science disciplines—Education, Economics, Sociology, and Psychology—as well as Computing, compared to WOS and Scopus.
- The number of Google Scholar citations for mathematicians and computer scientists is higher than that in Web of Science (WOS) and Scopus, but lower for high-energy physicists.
Variations or errors in name spelling should be taken into consideration:
- Various spellings of an author’s name.
- Differently formatted names in one source.
- Alternative names for an author.
- Typographical errors.
- Combining different authors who share the same name.
The Author Identification provides a unique number for every author and helps find and recognize a specific author and avoid confusion with other similarly named authors.
The most commonly used Author Identifiers are: Orcid ID (Open Researcher & Contributor ID), Scopus Author ID (Elsevier), Web of Science ResearcherID (Clarivate). More about Author Identifiers
Instructions
There are two ways to find h-index of the author:
- From your own profile
- Log on with your Google account and click ‘My Profile’ at the top of the Scholar homepage.
- Click on the search symbol on the right side of the page and type the last name and initials of the author in the opened search field.
- Then click search button (note: Google Scholar provides an H-index only for researchers who created a user profile for themselves).
- Then click the name of the author.
The following screen displays h-index of the author, according to the items indexed within Google Scholar.
- By ‘Advanced Search’
- Go to ‘Advanced Search’ and enter the full name or last name and initials of the author in the ‘Return articles authored by’ field and click ‘Search’.
- Click on the name of the author.
The following screen displays h-index of the author.