Essential Science Indicators - Hot Papers
Papers generally reach their citation peak two, three, or four years after publication. A small group of papers, however, are recognized very soon after publication, reflected by rapid and significant numbers of citations. These papers are often key papers in their fields and are referred to as hot papers.
Time Period for Counts
We measure the 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 current sampling of citations, we count citations from only the most recent two-month period.
Field and Age Variation
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 bi-monthly 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.
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 papers from journals covered in Web of Science Core Collection are counted.
Counts are based on a journal set categorized into 22 broad fields. Fields are defined by a unique grouping of journals with no journal being assigned to more than one field. They include: