Scale-free networks are rare

, a pattern with broad implications for the structure and dynamics of complex systems. However, the universality of scale-free networks remains controversial. Here, we organize different definitions of scale-free networks and construct a severe test of their empirical prevalence using state-of-the-art statistical tools applied to nearly 1000 social, biological, technological, transportation, and information networks. Across these networks, we find robust evidence that strongly scale-free structure is empirically rare, while for most networks, log-normal distributions fit the data as well or better than power laws. Furthermore, social networks are at best weakly scale free, while a handful of technological and…

• NS
  National Science Foundation

  Awards: IIS-1452718, 1452718
• NI
  National Institutes of Health

  Award: 1S10OD012300
• UO
  University of Colorado Boulder