Using the Co-Citation Network to Indicate Article Impact

Scholarly outputs are growing in number and frequency, driving the requirement to research new early indica-tion metrics. Historically, citations have been used as an independent indication of the significance of scholarly material. However, citations are very slow to accrue since they can only be made by subsequently published material. This enforces a delay of a number of years before the citation impact of a publication can be accurately judged. Existing early indication metrics, such as download metrics and web based link analysis, have obtained correlation results. Brody [1] finds a good correlation between download metrics and subsequent impact by citation, while Thelwall [2] finds very little correlation between Google’s PageRank and the number of links (or citations) to a web site, suggesting neither is a good surrogate indicator for the other. While valid studies, neither take account of the quality assessment factor of peer-review citation. This work presents an investigation into new metrics which utilize the co-citation network in order to rate a publications impact. A co-citation represents a relationship, that is established indirectly via citations, between two articles both cited by the same publication. With each publication citing a good number of others, a single direct citation to a paper will establish a good number of co-citation links to this same paper. Further, these relationships will exist with older material whose citation impact may already be established. Figure 1 demonstrates the significant difference between the citation network and co-citations networks for a single publication (p). On the left is th