title: The more publication, the higher impact factor: citation analysis of top nine gastroenterology and hepatology journals.
abstract: BACKGROUND
  The impact factor (IF), as the most important criterion for journal's quality measurement, is affected by the self-citation and number of publications in each journal.
  
  
  OBJECTIVE
  To find out the relationship between the number of publications and self-citations in a journal, and their correlations with IF.
  
  
  METHODS
  Self-citations and impact factors of nine top gastroenterology and hepatology journals were assessed during the seven recent years (2005-2011) through Journal Citation Reports (JCR, ISI Thomson Reuters).
  
  
  RESULTS
  Although impact factors of all journals increased during the study, five out of nine journals increased the number of publications from 2005 to 2011. There was an increase in self-citation only in the journal of HEPATOLOGY (499 in 2005 vs. 707 in 2011). Impact factors of journals (6.5 ± 3.5) were positively correlated with total number of publications (248.6 ± 91.7) (R: 0.688, P < 0.001). Besides, the self-citation rate (238.73 ± 195.317) was highly correlated with total number of publications in each journal (248.6 ± 91.7) (R: 0.861, P < 0.001). On the other hand, impact factor without self-citation (6.08 ± 3.3) had a correlation (R: 0.672, P < 0.001) with the number of published items (248.6 ± 91.7).
  
  
  CONCLUSIONS
  The number of articles and self-citation have definite effects on IF of a journal and because IF is the most prominent criterion for journal's quality measurement, it would be a good idea to consider factors affecting on IF such as self-citation.
authors: Kowsar Corporation, Hoensbroek, The Netherlands ; Baqiyatallah Research Center for Gastroenterology and Research Center, Tehran, IR Iran.
authors: Pegah
authors: P
authors: Karimi Elizee
authors: Romina
authors: R
authors: Karimzadeh Ghassab
authors: Azam
authors: A
authors: Raoofi
authors: Seyyed Mohammad
authors: SM
authors: Miri
keywords: Gastroenterology; Journal Impact Factor; Self-Citation