title: Impact of self-citation on the H index in the field of academic radiology.
abstract: OBJECTIVE
  The Hirsch Index (H index) is widely applied as a metric of scientific productivity. The purpose of this study was to evaluate the role of self-citation on the H index in academic radiology.
  
  
  METHODS
  Through the National Resident Matching Program's Web site, one third (47/139) of radiology residency programs were selected randomly. All chairpersons and full professors were included. Using the Scopus database, we calculated the H index as well as the number of cumulative citations with and without inclusion of self-citations. We determined the proportion of academic staff in which H index increased by one, two, or greater than two integers. We also correlated the proportional increase in H index before and after inclusion of self citations with the number of publications.
  
  
  RESULTS
  A total of 487 academic staff (47 chair and 440 professors) was identified. Because of self-citation, mean ± SD of the H index increased from 13.7 ± 9.9 to 14.0 ± 10.2; mean ± SD of cumulative citations increased from 1804 ± 1889 to 1870 ± 1971. H index numbers did not change in 376/487 (77%) authors as a result of self-citation. There was no correlation between number of publications and proportional change of H index.
  
  
  CONCLUSIONS
  The effect of self-citation is minimal in academic radiology, as evidenced by the fact that cumulative citations increase by only 2% and the large majority of H index values do not change by even a single integer after inclusion of self-citation.
authors.affiliation: Neuroradiology Department, Mayo Clinic, Rochester, MN 55905, USA.
authors.forename: Arash Ehteshami
authors.initials: AE
authors.lastname: Rad
authors.forename: Leili
authors.initials: L
authors.lastname: Shahgholi
authors.forename: David
authors.initials: D
authors.lastname: Kallmes
mesh_terms: D000046:Academic Medical Centers / Q000706:statistics & numerical data*; D004526:Efficiency; D007396:Internship and Residency / Q000706:statistics & numerical data*; D055811:Journal Impact Factor; D010506:Periodicals as Topic / Q000706:statistics & numerical data*; D011871:Radiology / Q000191:economics*; D014481:United States