Fig. 4

Results of differential analyses of out-centralities. Sender nodes of successful recommendation letters have significantly larger degree and PageRank out-centralities than sender nodes of unsuccessful letters (two-sided MWW test). For receiver nodes, there are no significant differences. See Table 3 for P-values underlying the significance annotations. The very similar results for the closeness centrality and the harmonic centrality can again be explained by the fact that these two centrality measures are closely related