Lobby index as a network centrality measure

We study the lobby index (l-index for short) as a local node centrality measure for complex networks. The l-index is compared with degree (a local measure), betweenness and Eigenvector centralities (two global measures) in the case of a biological network (Yeast interaction protein-protein network) and a linguistic network (Moby Thesaurus II). In both networks, the l-index has a poor correlation with betweenness but correlates with degree and Eigenvector centralities. Although being local, the l-index carries more information about its neighbors than degree centrality. Also, it requires much less time to compute when compared with Eigenvector centrality. Results show that the l-index produces better results than degree and Eigenvector centrality for ranking purposes.