Figure 1

Perturbation clustering in activity networks. (a) Activity networks of all projects (project 1 top-left to project 14 bottom-right). Node size denotes out-degree. The top 3 cascades (i.e connected components of perturbed activities) in each network are shown with a red color (from dark red for the top cascade to light red for the 3rd cascade). (b) Activity network from Project 6. Node color indicates the type of perturbation: early for negative perturbation, on-time if there is no perturbation, late for a positive perturbation, and very late for delays larger than 30 days. We observe a clustering of perturbations within network neighborhoods. (c) Extent of the observed perturbations, measured by the correlation between absolute perturbation values of activities as a function of their network distance. Network distance is computed as the outgoing shortest path between two nodes in the directed network. In order to model random expectation, for each project we compute the average correlation values across 50 random controls obtained by shuffling perturbations across completed activities. The gray area corresponds to the average and 2 standard deviations of these values across the 14 projects (see Methods)