Fifty years of impact factor: pros and cons

BACKGROUND: The Impact Factor (IF) was thought up 50 years ago, and it is currently the best available bibliometric index. Despite its shortcomings, the IF is widely used and offers, at present, the best simple tool to help libraries decide which journals to purchase. DISCUSSION: The use of the term "impact factor" has gradually evolved, especially in Europe, to include both journal and author impact. With this meaning, it has become the most used tool in evaluating scientific quality in decisions regarding funding and academic career. This ambiguity and use of IF to compare authors may be misleading. There is poor correlation between the citation frequency of a certain article and the IF of the journal in which it is published. There is a marked bias towards the English language journals compared with those in other languages. Even within the field of Occupational Medicine, the distribution of IF exhibits a wide spread between specialty subsets. CONCLUSION: The IF is a flawed measure of quality of academic staff performance. Searching for the highest IF is not equal to searching for the truth. There is still much work to be done to develop truly objective measures of scientific quality. Like all measures, the use of IF has to be tempered with knowledge of its limitations and common sense.