Although there are many measures of centrality of individuals in social networks, and those centrality measures can be applied
to the analysis of authors’ importance in co-authorship networks, the distribution of an author’s collaborative relationships
among different communities has not been considered. This distribution or extensity is an important aspect of authors’ activity.
In the present study, we will propose a new measure termed extensity centrality, taking into account the distribution of an
author’s collaborative relationships. In computing the strength of collaborative ties, which is closely related to the extensity
centrality, we choose Salton’s measure. We choose the ACM SIGKDD data as our testing data set, and analyze the result of authors’
importance from different points of view.