Lies, damned lies, and impact factors. Physics Today online editorial
garfield at CODEX.CIS.UPENN.EDU
Wed Oct 13 14:54:15 EDT 2010
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
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.
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