The impact factor, often abbreviated IF, is a measure reflecting the average number of citations to articles published in science and social science journals.
The impact factor of a journal for a given year is the average number of citations received per paper published in that journal during the two preceding years. If a journal has an impact factor of 3 in 2008, then its papers published in 2006 and 2007 received 3 citations each on average.
The 2008 impact factor of a journal would be calculated as follows:
A = the number of times articles published in 2006 and 2007 were cited by indexed journals during 2008
B = the total number of "citable items" published by that journal in 2006 and 2007.
2008 impact factor = A divided by B
The 2008 impact factors are actually published in 2009--they cannot be calculated until all of the 2008 publications have been received and processed by the indexing company.
It is frequently used as a proxy for the relative importance of a journal within its field, with journals with higher impact factors deemed to be more important than those with lower ones.
Due to differences in publishing patterns by discipline, impact factors cannot be compared between disciplines.
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3. The Journal Search page will let you search for journals by full journal title, abbreviated journal title, title word, or ISSN. Or click view list of full journal titles to see a complete list of titles.
To view the Impact Factor for a group of journals by Subject Category:
The results page will show the impact factor of the journals in your selected category or categories. For additional analysis and explanation of impact factor and other measures, click the journal's title (e.g. ACTA PHYSIOL).