An Impact Factor is one measure of the relative importance of a journal, individual article or scientist to science and social science literature and research. Each index or database used to create an impact factor uses a different methodology and produces slightly different results, revealing the importance of using several sources to judge the true impact of a journal's or scientist’s work. Included on this page is information on Journal Impact Factor, Author Impact Factor, and Article Impact Factor.
Informed and careful use of these impact data is essential, and should be based on a thorough understanding of the methodology used to generate impact factors. There are controversial aspects of using impact factors:
- It is not clear whether the number of times a paper is cited measures its actual quality.
- Some databases that calculate impact factors fail to incorporate publications including textbooks, handbooks and reference books.
- Certain disciplines have low numbers of journals and usage. Therefore, one should only compare journals or researchers within the same discipline.
- Review articles normally are cited more often and therefore can skew results.
- Self-citing may also skew results.
- Some resources used to calculate impact factors have inadequate international coverage.
- Editorial policies can artificially inflate an impact factor.