About Journal Impact Index

With regard to the IGBB website...

Journal Impact Index for a particular article/journal is taken from the Scimago Journal & Country Rank database. For an article published in journal J in year Y, the impact index used is the Scimago "Cites/Doc (2 years)" value for Y-1; e.g., for a Nature article published in 2018, the impact index is the "Cites/Doc (2 years)" for 2017 (i.e., 24.753). There are four exceptions which are indicated by symbols immediately following the Journal Impact Index value or space where a value is absent:
  • An article was published in the first year for which a "Cites/Doc (2 years)" was available. Since there is no Y-1 value, Y is used instead.
  • § The article was published in a journal before that journal was indexed by the Scimago Journal & Country Rank database. In such instances, the first published "Cites/Doc (2 years)" value is used.
  • λ The journal is not indexed by Scimago. Of the hundreds of articles in the IGBB database, only two are in journals not indexed by Scimago.
  • δ The journal is currently in its inaugural year of publication, and thus a "Cites/Doc (2 years)" value is not available for it at present.
Until 2018, the IGBB obtained its Journal Impact Indexes from the subscription-based Web of Science Journal Citation Reports (JCR) database compiled by Thomson Reuters. However, the JCR was purchased by Clarivate Analytics, and Mississippi State University's subscription to JCR was not renewed. Of note, the Scimago average citations per document over a 2-year period [Cites per Doc. (2y)] values are computed using the same formula employed to determine JCR Impact Factors.

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