The desire of researchers within the scientific community is for their publications to be evaluated in a precise, valid, verifiable, reliable, transparent, and equitable manner. Currently, there is no mathematical formula that can quantify the "quality" of an article. Hopefully, the impact factor (IF) can be employed as an indirect indicator of this quality while always bearing in mind that its true objective consists in measuring the international influence or impact of a journal within the research community.
It cannot be sufficiently emphasized that the impact factor was created with the intent of comparing journals, not authors or individual articles.
Nevertheless, if we decide to use the IF as a tool to evaluate the quality of the individual investigator's scientific productivity, we need to have a combination of other indicators while taking into account their known limitations. As highlighted by Garfield (1999), there is a bias when comparing IF of journals relating to different categories in the Journal Citation Report (JCR) due to, among other factors, the fact that different disciplines have widely differing citation practices.
In a recent article, Sombatsompop and Markpin (2005) proposed a formula to minimize these differences between fields. The authors achieved their objective but generated what could be considered a grave injustice: an excessive widening of differences in values between the journals relating to the same category. Hence, using one of their examples and calculations for the "Neurosciences" category for equivalence between the IF and a derived index, publication credit (PC), the value of the journal classified 49th in the ranking (IF or PC Ο 3,275) is 93.5 times greater than that of the journal located at the 193rd position in the ranking (IF or PC Ο 0.035). The new formula, impact factor point average (IFPA), proposed by the authors, far from reducing these differences, actually widens them such that, for the same example (Neurosciences) the difference between the same two journals is a factor of 2,997. The difference would be even greater if the comparisons were between the first and the last in the rankings of each category. As such, an article published in Annual Review of Neuroscience (the top ranked journal in its category in 2002) with an IF of 27.152 would be, according to the authors of the article, 32,569 times "better" than one published in a journal that is at the bottom of the rankings, a magnitude that applies, more or less, in the rest of the categories examined.