title: Factors associated with the Journal Impact Factor (JIF) for Urology and Nephrology Journals.
abstract: OBJECTIVE
  The Journal Impact Factor (JIF) is an index used to compare a journal's quality among academic journals and it is commonly used as a proxy for journal quality. We sought to examine the JIF in order to elucidate the main predictors of the index while generating awareness among scientific community regarding need to modify the index calculation in the attempt to turn it more accurate.
  
  
  METHODS
  Under the Urology and Nephrology category in the Journal Citations Report Website, the top 17 Journals by JIF in 2011 were chosen for the study. All manuscripts' abstracts published from 2009-2010 were reviewed; each article was categorized based on its research design (Retrospective, Review, etc). T and correlation tests were performed for categorical and continuous variables respectively. The JIF was the dependent variable. All variables were then included in a multivariate model.
  
  
  RESULTS
  23,012 articles from seventeen journals were evaluated with a median of 1,048 (range=78-6,342) articles per journal. Journals with a society affiliation were associated with a higher JIF (p=0.05). Self-citations (rho=0.57, p=0.02), citations for citable articles (rho=0.73,p=0.001), citations to non-citable articles (rho=0.65,p=0.0046), and retrospective studies (rho=-0.51,p=0.03) showed a strong correlation. Slight modifications to include the non-citable articles in the denominator yield drastic changes in the JIF and the ranking of the journals.
  
  
  CONCLUSIONS
  The JIF appears to be closely associated with the number of citable articles published. A change in the formula for calculating JIF to include all types of published articles in the denominator would result in a more accurate representation.
authors.affiliation: Department of Urology, University of Minnesota School of Medicine, Minneapolis, MN, USA.
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Sewell
authors.affiliation: Department of Urology, University of Minnesota School of Medicine, Minneapolis, MN, USA.
authors.forename: Oluwakayode O
authors.initials: OO
authors.lastname: Adejoro
authors.affiliation: Department of Urology, University of Minnesota School of Medicine, Minneapolis, MN, USA.
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Fleck
authors.affiliation: School of Public Health, Division of Biostatistics, University of Minnesota School of Medicine, Minneapolis, MN, USA.
authors.forename: Julian A
authors.initials: JA
authors.lastname: Wolfson
authors.affiliation: Department of Urology, University of Minnesota School of Medicine, Minneapolis, MN, USA.
authors.forename: Badrinath R
authors.initials: BR
authors.lastname: Konety
mesh_terms: D016206:Databases, Bibliographic; D055811:Journal Impact Factor; D016014:Linear Models; D009398:Nephrology / Q000706:statistics & numerical data*; D010506:Periodicals as Topic / Q000706:statistics & numerical data*; D011643:Publishing / Q000706:statistics & numerical data; D012107:Research Design; D018709:Statistics, Nonparametric; D014572:Urology / Q000706:statistics & numerical data*