“The journal impact factor is a quantitative measure of journal quality in the form of an index that charts the frequency with which articles from a journal are cited. The impact factor is a simple calculation that covers a 3-year period calculating the average number of times published papers are cited for up to 2 years after publication.”
"Publishing and Publication." The SAGE Encyclopedia of Qualitative Research Methods. Ed. Lisa M. Given. Vol. 2. Thousand Oaks, CA: SAGE Publications, 2008. 695-697. Gale Virtual Reference Library. Web. 24 Jan. 2014.