Table 1 Pitfalls of using impact factor [3, 4, 7–9]
From: The Hirsch index - a play on numbers or a true appraisal of academic output?
Pitfall | Detail |
|---|---|
Transparency issues | Thompson Scientific decides what is a "citable" research item. Books, book chapters and conference proceedings not included. |
Ambiguity in calculation | "The definition for citing items is broader than for cited items". Also, difficult to reproduce the calculation. |
Shortcomings of 2 - year temporal bracket for citations | Citation fluctuations make the inclusion of citations limited to the previous two years unreliable. |
No consideration of "citation half-life" in calculating IF ǂ | Citations change as the article and the journal itself matures. |
Over-representation | Medical literature in English language or by a particular publisher or from a particular geographic region (e.g. North America) or about a particular subject (e.g. basic sciences) or of a particular type (e.g.a review) is disproportionately represented and cited. |
Homonymy, Synonymy | Many authors sharing the same name or one article with many variants. Articles where author's name misspelled will be missed. |
Delays | Delays in registration of citations, delays in peer-review and publication process detrimental for journals of disciplines with long turn-over times. |
Abridged referencing | Many journals restrict the number of articles that can be cited by authors. Important research maybe potentially disregarded and not cited. |
Miscellaneous | "Gift" authorships, self-citations and "flattery" citations |