
How is the journal impact factor (JIF) calculated?
Put simply, a journal’s impact factor averages the number of citations received by a journal in a given year by the number of articles published in the previous two years. For example, a journal’s JIF for the year 2009 is calculated by taking the number of citations made in 2009 to the articles published in the journal in 2007 and 2008 and then dividing by the total number of articles published in that journal in 2007 and 2008.
This method of calculation will therefore result in a different JIF each year
Only references in articles within the 10,000+ journals indexed in Web of Science / JCR are counted in the JIF calculation.
My RI by University College Dublin, Dublin City University, Dublin Institute of Technology, The National University
of Ireland, Maynooth and the NDLR adapted by Marion Kelt, Glasgow Caledonian University is licensed
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Based on a work at http://www.ndlr.ie/myri/.