The impact factor of scientific journals by broad category

In this paper, we firstly describe the history, the calculation, the bibliometric use and the restrictions that must be kept in mind when journals' impact factors (IF) are used as a measure of the quality of research. Secondly, we present two tables attempting to point out the relative impact of the different scientific fields as well as to help researchers in publishing their work in the journal with the highest possible IF. The tables have been constructed using the journals' IFs that are included in the Journal Citation Reports published on 2002 by the Institute for Scientific Information (ISI). In the first table, the journals of ISI were re-tabulated in 50 board scientific categories, instead of the 120 that are used by ISI. In parallel, the number of ISI journals, their mean lFs and the percentage of journals with IF equal or greater than 1, 2, 4 and 5 are given by category. In the second table, the first 30 journals of each category are presented ranked according to their IFs. It is concluded that the vast majority of ISI journals, especially those with the highest IFs, belong to the biomedical sciences