A non-linear index to evaluate a journal's scientific impact
Information Sciences: an International Journal
What lies behind the averages and significance of citation indicators in different disciplines?
Journal of Information Science
Ten good reasons to use the EigenfactorTM metrics
Information Processing and Management: an International Journal
Relative status of journal and conference publications in computer science
Communications of the ACM
Journal of the American Society for Information Science and Technology
Structural indicators in citation networks
Scientometrics
Journal of the American Society for Information Science and Technology
Aggregating productivity indices for ranking researchers across multiple areas
Proceedings of the 13th ACM/IEEE-CS joint conference on Digital libraries
Hi-index | 0.02 |
The bibliometric measure impact factor is a leading indicator of journal influence, and impact factors are routinely used in making decisions ranging from selecting journal subscriptions to allocating research funding to deciding tenure cases. Yet journal impact factors have increased gradually over time, and moreover impact factors vary widely across academic disciplines. Here we quantify inflation over time and differences across fields in impact factor scores and determine the sources of these differences. We find that the average number of citations in reference lists has increased gradually, and this is the predominant factor responsible for the inflation of impact factor scores over time. Field-specific variation in the fraction of citations to literature indexed by Thomson Scientific's Journal Citation Reports is the single greatest contributor to differences among the impact factors of journals in different fields. The growth rate of the scientific literature as a whole, and cross-field differences in net size and growth rate of individual fields, have had very little influence on impact factor inflation or on cross-field differences in impact factor. © 2009 Wiley Periodicals, Inc.