Introspection: an analysis of the citation impact of stroke.

One indicator of the influence of a scientific journal is the extent to which its articles are cited by others. A widely applied measure in this regard is so-called journal impact factor, an index devised by Eugene Garfield1 to quantify the extent to which the articles of that journal are cited in other peer-reviewed publications. The impact factor is typically computed as the quotient A/B, where A is the total number of times that articles published in a journal in 2 consecutive years (eg, 2008 and 2009) were cited in articles published during the following year (eg, 2010), and B is the total number of “citable items” published by that journal in those 2 years (see “impact factor” on Wikipedia http://en.wiki pedia.org/wiki/Impact_factor [accessed July 21, 2011]). As quoted by Lo and Fisher in their recent editorial,2 the 2009 impact factor for Stroke was 7.041, compared to 8.172, 9.317, and 18.126 for the journals Neurology, Annals of Neurology, and Lancet Neurology, respectively. An obvious shortcoming of the impact factor, so-computed, is that it represents merely a numeric average that does not shed light on the extent to which the individual articles of a journal contribute to its overall citation impact. Thus, the intent of the present contribution is to provide an expanded analysis of the citation impact of articles and reviews published in Stroke in the years 2008 and 2009.