Essential Science IndicatorsSM
Understanding Core Data - Scientists
Citation counts are a form of peer recognition and generally reflect
the dependence of the scientific community on the work of individual
scientists. It could be argued that highly cited scientists form the
essential core of the scientific community. Many highly cited
scientists have also received peer recognition in the form of honorific
Counting method for articles and citations:
All authors on a paper are credited equally for the paper. All
citations received by a paper are credited equally to all the
authors on the cited paper. No restrictions are made on the citing
items in compiling the citation counts, other than that they are
recorded from Clarivate Analytics-indexed journals only.
Time period for counts (cites, papers, cites per
The time period for
Essential Science Indicators from
Reuters counts is 10 years, plus partial year counts for
the current year (data is updated six times a year). This means
that any papers in the 10+ year period can be cited by any items in
that same period. Clarivate Analytics database years (the actual years
when items are entered into the Clarivate Analytics database, which is
not necessarily the publication year) are used to define the time
Types of items counted:
Papers are defined as regular scientific articles, review articles,
proceedings papers, and research notes. Letters to the editor,
correction notices, and abstracts are not counted. Only Thomson
Reuters-indexed journal articles or papers are counted.
Essential Science Indicators counts are based on an
Clarivate Analytics journal set (see complete
journal list for
Essential Science Indicators) categorized into
22 broad fields.
Fields are defined by a unique grouping of journals, with no
journal being assigned to more than one field. The
Multidisciplinary field contains journals such as Science
and Nature which in an article-level
would be assigned to specific fields. This should be taken into
account when analyzing the field ranking of an individual
scientist, institution, or country.
Authors selected for listing in Essential Science
Indicators must meet a cumulative citation count threshold for
the 10+ year period. More information about the actual
thresholds used in
Essential Science Indicators.
The absence of an author name in Essential Science
Indicators means the author did not meet the citation
threshold in any field.
Authors having the same last name and initials may represent
multiple individuals. This is especially likely in the case of
common surnames. The ability to break the name by field may to some
degree disambiguate person X in field Y from person X in field Z;
however, keep in mind that a listed name can still represent more
than one author within the same field.
Name variations and variations in initials:
Individual authors may appear with or without middle initials, in
which case two entries may need to be consulted. This is also true
for authors who have changed their names, for example, from maiden
to married names, or authors whose last names appear in multiple
Scientists in the rankings are numbered from 1 to N, depending on
the ranking option selected, with no repeated ranks for ties (ties
are then ranked alphabetically). Ranking options include citations,
papers, citations per paper, and alphabetic.
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