Fig. 2

Distributions of in-/out-strength (s_in/s_out) at each layer and the full aggregated network (AGG.). All values of s are shifted by 1 to account for nodes with zero values on the log-log plots. Lines fit a power-law distribution P(s)=s^−λ using the maximum likelihood estimator and a p-value for the goodness of fit is obtained using a bootstrapping procedure (Clauset et al. 2009). The mean values and standard deviations of exponents λ are shown in the legends, and p-values obtained via 1000 bootstrap replications are reported in parenthesis