HITS is principal components analysis

In this work, we show that Kleinberg's hubs and authorities model (HITS) is simply Principal Components Analysis (PCA; maybe the most widely used multivariate statistical analysis method), albeit without centering, applied to the adjacency matrix of the graph of web pages. We further show that a variant of HITS, SALSA, is closely related to correspondence analysis, another standard multivariate statistical analysis method. In addition to provide a clear statistical interpretation for HITS, this result suggests to rely on existing work already published in the multivariate statistical analysis litterature (extensions of PCA or correspondence analysis) in order to analyse or design new web pages scoring procedures.