Thomson Reuters Statement Regarding the San Francisco Declaration
on Research Assessment

Thomson Reuters acknowledges the effort of the San Francisco Declaration to address research assessment and to encourage the informed and rational use of citation data as a primary source of performance evaluation. No one metric can fully capture the complex contributions scholars make to their disciplines, and many forms of scholarly achievement should be considered.

The Journal Impact Factor is singled-out in the Declaration not for how it is calculated, but for how it is used.  Thomson Reuters would like to provide information on what the Journal Impact Factor is uniquely able to offer, in support of its correct use.

A Journal Impact Factor considers the citation performance of a journal as a whole unit, more than the sum of diverse published items.  It is based on the cited references generated by the scholarly community, compiled objectively across thousands of journals and proceedings on an annual basis.  Each title's Journal Impact Factor contains a single, current year of citations to the prior two year period, scaled according to a count of the quantity of scholarly material published in that same title over the same timeframe.  Journals cannot dominate the ranking simply by their volume of published items. What generates journal impact is having a large number of citations compared to the volume of scholarly content.

The Journal Impact Factor does not measure the quality of an individual article in the journal — since it is not based on the citation of individual publications — but it does correlate to the reputation of the journal in its field.  The editorial process strives to ensure the quality of the scholarship and the relevance to the audience of every article published.  Each item selected for publication in the journal is subjected to this same editorial oversight and peer-review that is applied to all materials published in the journal. Scientists and scholars contribute their time and effort as reviewers and editors, to ensure the quality of the journals that matter to them. Over time, this editorial attention gives the journal a reputation for relevance and excellence. It also has the potential to result in a higher Journal Impact Factor compared to other publications with similar subject matter.  The choice of a journal in which to publish is not unimportant, but appropriate publication venues should be topically relevant and scientifically appropriate according to the content of the article.  These characteristics of a journal are not included in the Journal Impact Factor calculation.   

The Web of Science, the comprehensive citation index from Thomson Reuters, is developed from the same production data used to create the Journal Citation Report (JCR), but presented at the level of individual published items.  Items and their citations in Web of Science can be considered on their own or grouped by author, institution, department, field, etc.  With the addition of extensive research analytics tools, a multidimensional view of research output can be developed in comparison with baselines calculated on matched content. 

Thomson Reuters continues to encourage publishers, researchers and funders to consider the correct use of the many metrics available, including the Journal Impact Factor and data from the Web of Science, when performing research assessments. 

Methods for the preparation of the Journal Impact Factor

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