CMAJ and several other general medical journals fared well when the 2002 Science Edition of ISI's Journal Citation Reports (JCR) was released in June. JCR includes citation data for more than 5500 journals in 168 subject categories. CMAJ is 1 of 107 journals in the general and internal medicine category.
Among the numerous citation-based indicators JCR publishes, impact factors receive the most attention. They are used by librarians, publishers, advertisers, editors and authors to rank and assess the “scientific impact” of journals. The impact factor is obtained by dividing the number of current-year citations to all items published in a journal in the 2 previous years by the number of source articles published in the same period. Although there has been much debate over the use and misuse of impact factors, many consider them a significant indicator of a journal's quality and prestige. Editors routinely use the impact factor to gauge their own performance and hope that a “good impact factor” will attract higher quality submissions.
CMAJ saw its impact factor rise from 2.8 in 2001 to 3.2 in 2002, a 14% increase (see table). The highest impact factor among internal medicine journals was 11.4 for the Annals of Internal Medicine.
But what do these numbers really mean? The impact factor is a measure of the frequency with which the “average article” in a journal has been cited in the scientific literature in a particular year. Obviously, some articles are never cited and others are highly cited. CMAJ's top-cited articles in recent years include:
· Secular trends in the body mass index of Canadian children (CMAJ 2000;163[11]:1429-33, 36 citations);
· Recommendations for the management and treatment of dyslipidemia: Report of the working group on hypercholesterolemia and other dyslipidemias (CMAJ 2000;162 [10]: 1441-7, 36 citations);
· Preventive health care, 2001 update: Should women be routinely taught breast self-examination to screen for breast cancer? (CMAJ 2001;164 [13]: 1837-46, 41 citations). — Glenda Proctor, CMAJ