Lies, damned lies, and impact factors. Physics Today online editorial

[Eugene Garfield]

Lies, damned lies, and impact factors
By Physics Today on October 11, 2010 2:31 PM 

In a commentary published four years ago in the Journal of the American Medical 
Association, Eugene Garfield outlined the history of the journal impact factor.

He and Irving Sher created the impact factor in the early 1960s to help determine 
which journals should be included in the then new Science Citation Index. Relying 
solely on the number of papers published in a journal, they feared, risked ignoring 
thin, highly selective journals, such as the Proceedings of the National Academy 
of Sciences.

In case you didn't know, a journal's impact factor for a given year is the average 
number of citations received by papers published in the journal during the two 
preceding years. Letters to the editor, editorials, book reviews, and other non-
papers are excluded from the impact factor calculation.

Fulltext: http://blogs.physicstoday.org/thedayside/2010/10/lies-damned-lies-and-
impact-factors.html