Major Limitations of Impact Factors of Journals

Publishing articles in journals with impact factors can sometimes make or break a scientist's career, as it often influences decisions regarding promotion, tenure, funding allocation to various university departments and divisions, etc.

However, the use of impact factors for such purposes has often been criticized as there are many potential limitations to journal impact factors. Below we list 20 potential limitations.

Limitations of Journal Impact Factors

• Journal impact factors are not representative of individual journal articles
• Journal impact factors correlate poorly with actual citations of individual articles
• Authors use many criteria other than impact when submitting to journals
• Potentially manipulateable via self citations
• Journals can inflate impact factors by publishing greater proportion of review articles, which are heavily cited
• Long articles collect many citations and give high journal impact factors
• Short publication lag allows many short term journal self citations and gives a high journal impact factor
• Citations in the national language of the journal are preferred by the journal's authors
• journal self citation: articles tend to preferentially cite other articles in the same journal
• Editorial board coerced self citation: editors may suggestively coerce authors to include and cite additional relevant articles from the same journal as criteria for resubmitting manuscript

• Citations to "non-citable" items are erroneously included in the database
• Coverage of the database is not complete
• Books are not included in the ISI database as a source for citations
• Database has an English language bias
• The database of included journals may vary over time, causing instability of impact factor values
• Research fields with literature that have high rates of citation due to the nature of rapidly updated and outdated study results
• Impact factor depends on dynamics (expansion or contraction) of the research field
• Small research fields tend to lack journals with high impact
• Relations between fields (clinical v basic research, for example) strongly determine the journal impact factor