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Lecture 9 Measures and Metrics. Structural Metrics. Degree distribution Average path length Centrality Degree, Eigenvector, Katz, Pagerank , Closeness, Betweenness Hubs and Authorities Transitivity Clustering coefficient Reciprocity Signed Edges and Structural balance Similarity
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Lecture 9 Measures and Metrics
Structural Metrics • Degree distribution • Average path length • Centrality • Degree, Eigenvector, Katz, Pagerank, Closeness, Betweenness • Hubs and Authorities • Transitivity • Clustering coefficient • Reciprocity • Signed Edges and Structural balance • Similarity • Homophily and Assortativity Mixing
Similarity • Structural Equivalence • Cosine Similarity • Pearson Coefficient • Euclidian Distance • Regular Equivalence • Katz Similarity
Homophily and AssortativeMixing • Assortativity: Tendency to be linked with nodes that are similar in some way • Humans: age, race, nationality, language, income, education level, etc. • Citations: similar fields than others • Web-pages: Language • Disassortativity: Tendency to be linked with nodes that are different in some way • Network providers: End users vs other providers • Assortative mixing can be based on • Enumerative characteristic • Scalar characteristic
Modularity (enumerative) • Extend to which a node is connected to a like in network • + if there are more edges between nodes of the same type than expected value • - otherwise is 1 if ciand cj are of same type, and 0 otherwise err is fraction of edges that join same type of vertices ar is fraction of ends of edges attached to vertices type r
Assortativecoefficient (enumerative) • Modularity is almost always less than 1, hence we can normalize it with the Qmax value
Assortativecoefficient (scalar) • r=1, perfectly assortative • r=-1, perfectly disassortative • r=0, non-assortative • Usually node degree is used as scale
Assortativity CoefficientVarious Networks M.E.J. Newman. Assortative mixing in networks