Journal Impact Factor: Do the Numerator and Denominator Need Correction?

Abstract

To correct the incongruence of document types between the numerator and denominator in the traditional impact factor (IF), we make a corresponding adjustment to its formula and present five corrective IFs: IF _Total/Total, IF _Total/AREL, IF _AR/AR, IF _AREL/AR, and IF _AREL/AREL. Based on a survey of researchers in the fields of ophthalmology and mathematics, we obtained the real impact ranking of sample journals in the minds of peer experts. The correlations between various IFs and questionnaire score were analyzed to verify their journal evaluation effects. The results show that it is scientific and reasonable to use five corrective IFs for journal evaluation for both ophthalmology and mathematics. For ophthalmology, the journal evaluation effects of the five corrective IFs are superior than those of traditional IF: the corrective effect of IF _AR/AR is the best, IF _AREL/AR is better than IF _Total/Total, followed by IF _Total/AREL, and IF _AREL/AREL. For mathematics, the journal evaluation effect of traditional IF is superior than those of the five corrective IFs: the corrective effect of IF _Total/Total is best, IF _AREL/AR is better than IF _Total/AREL and IF _AREL/AREL, and the corrective effect of IF _AR/AR is the worst. In conclusion, not all disciplinary journal IF need correction. The results in the current paper show that to correct the IF of ophthalmologic journals may be valuable, but it seems to be meaningless for mathematic journals.