What are impact factors?
The impact factor for journal X = the number of citations in a given year to all articles published in journal X for the previous two years, divided by the number of articles in that journal for those previous two years
What should concern you about cited reference searching and impact factors?
- Citation rates vary widely from field to field and shouldn't be taken at face value, but considered relative to the field of research
- Citation rate may be based on a few prolific authors citing each other, including self citations
- Citation searching works better for journal articles than books
- Coverage of your particular field in the citation database may be weak
- Cross-disciplinary research may produce fewer citations
- Distribution of the citations over time might be more indicative of their importance than an initial high citation count shortly after publication
- Impact factors are a measure of the journal as a whole, not individual papers or researchers
- Impact factors may play a too important role in hiring and tenure decisions without considering other measures
- Some journals also cite articles in editorials, reviews, news, and other non-research articles to increase the number of cites
- The research may too recent and not widely known, like emerging fields
- The quality of the journal producing the citation
- There is a growing tendency of some researchers to go after topics likely to get into high-impact journals, which jeopardizes creativity, and this can skew the course or even slow the pace of science
- There is no guarantee that every paper which ought to be cited will be cited. An un-cited author may be ahead of his peers. Mendel and his genetics work went unappreciated for years
