Essential Science IndicatorsSM
Understanding Core Data - Hot Papers
Generally, papers reach their citation peak two, three, or even four
years after publication. However, a small group of papers is recognized
very soon after publication, reflected by rapid and significant numbers
of citations. These papers are often key papers in their fields. We use
a special filter to detect such "hot" papers. This involves looking at
recently published papers and unusual citation activity in a current
time period. We also take into account the varying citation rates
What are Hot Papers?
Hot Papers are papers that receive citations soon after
publication, relative to other papers of the same field and age.
Time period for counts:
We measure age for hot papers in two-month periods rather than
years, and we scan only those papers published in the last two
years to see if they are receiving more citations than the norm. To
get a very current sampling of citations, we count citations from
only the most recent two-month period. The time periods are defined
by Clarivate Analytics database processing dates (the actual date when
items are entered into the Clarivate Analytics database, which is not
necessarily the publication date). Note that the data is updated
bimonthly (six times a year).
Field and age variations:
To correct for field variations in citation rate, each field is
treated separately. Furthermore, since older papers tend to be
cited more than newer (just published) papers, a separate analysis
is made for each two-month grouping of papers, giving a total of 12
groupings over the two-year period.
A paper is selected as a Hot Paper if it meets a citation-frequency
threshold determined for its field and bimonthly group.
Citation-frequency distributions are compiled for each field and
cohort. Thresholds are set by finding the closest citation count
that would select the top fraction of papers in each field and
period. The fraction is set to retrieve about 0.1% of papers. More
information about the actual
Essential Science Indicators.
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.
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