The Article Influence Score measures the relative importance of the journal on a per-article basis. It is the journal's Eigenfactor Score divided by the fraction of articles published by the journal. That fraction is normalised so that the sum total of articles from all journals is 1.
The mean Article Influence Score is 1.00. A score greater than 1.00 indicates that each article in the journal has above-average influence. A score less than 1.00 indicates that each article in the journal has below-average influence.
In 2006, the top journal by Article Influence Score was Annual Reviews of Immunology, with an article influence of 27.454. This means that the average article in that journal has twenty seven times the influence of the mean journal in the Journal Citation Reports (JCR).
Article Influence uses Thomson Reuters (ISI Web of Knowledge) citation data.