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What is the Impact Factor?


What is the Impact Factor?

The impact factor was created by the company Thomson Reuters. It is the oldest and best-known measure of journal metrics. 

The impact factor measures how often the articles in scholarly journals are cited. Journals with high impactor factors are usually considered prestigious

Pepperdine does not subscribe to the Journal Citation Reports (JCR) database from Thomson Reuters, but it is important to remember that Thomson's impact factor is only one of several instruments for ranking the prestige of journals. Pepperdine subscribes to the database Cabell's Directories of Publishing Opportunities, which does provide data for Thomson Reuter's impact factor

Oct. 2016 -- Thomson Reuters was acquired by Onex Corporation and Baring Private Equity Asia the company is renamed Clarivate Analytics

1988 Thomson Reuters acquired the Institute for Scientific Information (ISI)

SCImago Journal & Country Rankings


Rankings are based on the number of times articles within a journal are cited and the prestige of the journals where the citations appeared.

About 29,000 journals are ranked by SCIMago

SCIMago's ranking criteria is very similar to the Eigenfactor. The main difference is that the Eignefactor analyzes journals from Thomson's Journal Citation Reports, while SCIMago ranks journals from Elsevier's Scopus Database.



The Eigenfactor ranks the over 8,000 journals that are included inThomson Journal Citation Reports (JCR) database.

Journals are ranked by the number of other journals that cite their articles. More weight is given to citations from prestigious journals.

Cabell's Directory of Publishing Opportunities

Cabell's Directory of Publishing Opportunities provides Impact Factors from Thomson Reuters Journal Citation Reports for many social sciences journals. Journals in the natural sciences and humanities are much less likely to appear in Cabell's Directory of Publishing Opportunities.

CiteScore from Elseiver

CiteScore from Elsevier

CitesScore from Elsevier is new freely available resource that ranks and evaluates over 22,000 journals based on how often their articles are cited by other journals. Here are some issues with this new metric:

  • Doesn’t always correlate with Clarivate Analytics (formerly Thomson Reuters) Impact Factor

  • Counts *all* document types such as letters and editorials

  • Elsevier, the company responsible for CiteScore, also publishes journals

  • CiteScore evaluates almost twice as many journals as Clarivate Analytics (Thomson Reuters) Impact Factor

  • Updated monthly (most journal ranking resources are updated annually)