Structure of the impact factor of journals included in the Social Sciences Citation Index:: Citations from documents labeled "editorial material"

We investigated how citations from documents labeled by the Institute for Scientific Information (ISI) as '' editorial material '' contribute to the impact factor of academic journals in which they were published. Our analysis is based on records corresponding to the documents classified by the ISI as editorial material published in journals covered by the Social Sciences Citation Index between 1999 and 2003 (50,273 records corresponding to editorial material published in 2,374 journals). The results appear to rule out widespread manipulation of the impact factor by academic journals publishing large amounts of editorial material with many citations to the journal itself as a strategy to increase the impact factor.