Impact factor bias and proposed adjustments for its determination

Background: The impact factor (IF), a qualitative parameter used to evaluate scientific journals, has several flaws. The aim of the study was to evaluate two of its important constraints, journal self‐citation and scientific field, and to investigate the potential for improvement. Methods: We studied the five or six highest impact journals from each of seven medical fields: anesthesiology, dermatology, genetics and heredity, immunology, general and internal medicine, ophthalmology and surgery. To correct for journal self‐citation, we divided the number of 1998 citations of papers published in 1996 and 1997, minus the self‐citations, by the number of papers published in the same period. For inter‐field normalization we divided the IF by the mean of the IFs of the upper quartile for the same category of medical field (IF/fcat). Results: For the 36 journals, there was a negative correlation between IF and self‐cited and self‐citing rates (rs = −0.765, P