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The Journal's impact factor rose by 0.611 units in 2002 to reach 6.567 (Figures 1 and 2). This is the largest ever one-year increase for AJRCCM. What does it mean?
The Institute for Scientific Information has published impact factors of biomedical journals since 1974 (1, 2). Despite serious limitations, this citation metric has become the most widely used index for ranking the overall quality of biomedical journals. Why are editors so attentive to impact factor (3-12)? They see science as a collective and cooperative enterprise: an edifice of knowledge built by contributions from successive generations of researchers (13). Each new article is based on the preceding research that the author cites, and a published article is of little significance unless other scientists cite it and build on it. (Between 22% and 46% of medical research articles attract not even one citation [14, 15].) When authors cite an article, it usually means they found it helpful when pursuing their own research. Editors recognize that researchers are in effect casting votes on the importance of a journal every time they cite it (16).
Listing references at the end of an article is a trademark of scholarship. Within a year of its launch in 1665, authors were placing references in the margins of the Philosophical Transactions (17). Footnotes first appeared in 1683 and remained the preferred method of referencing until the numbers grew too large. Endnotes first appeared in 1876 and are now the standard (17). Along the way, the number of references per article increased from less than 5 before 1700 to over 40 in 1950.
Investigators cite the work of previous investigators for several reasons: motivating new research, according credit for ideas, providing greater detail on methodology, highlighting errors in previous research, and persuading readers of the legitimacy of a new claim (18). In a survey of 26 authors on the motivation behind more than 900 citations, the significant reasons were to accord positive credit and to demonstrate that the author was up to date in a research discipline (19). But the dominant reason by far was persuasiveness: an author wanting to establish legitimacy for a new research claim. How well a reader is persuaded, however, will depend on the reputation of the scientist being cited...