Staying connected: Asymmetric disassembly and robustness in declining networks

The results of the first in-depth study of a declining business network over an extended period of time has been published in the Proceedings of the National Academy of Sciences. The study was based on the famous New York Garment Industry and was undertaken by CABDyN Co-Director Felix Reed-Tsochas and CABDyN member Serguei Saavedra in collaboration with Brian Uzzi at the Kellogg School of Management (Northwestern University).

Mechanisms that enable declining networks to avert structural collapse and performance degradation are not well understood. This knowledge gap reflects a shortage of data on declining networks and an emphasis on models of network growth. Analyzing >700,000 transactions between firms in the New York garment industry over 19 years, we tracked this network’s decline and measured how its topology and global performance evolved. We find that favoring asymmetric (disassortative) links is key to preserving the topology and functionality of the declining network. Based on our findings, we tested a model of network decline that combines an asymmetric disassembly process for contraction with a preferential attachment process for regrowth.

Our simulation results indicate that the model can explain robustness under decline even if the total population of nodes contracts by more than an order of magnitude, in line with our observations for the empirical network. These findings suggest that disassembly mechanisms are not simply assembly mechanisms in reverse and that our model is relevant to understanding the process of decline and collapse in a broad range of other networks undergoing severe contraction, such as ecological networks facing habitat destruction, networks of neurons affected by degenerative diseases, or the rapidly shrinking network of interbank loans.

S. Saavedra, F. Reed-Tsochas and B. Uzzi, Asymmetric disassembly and robustness in declining networks, Proc. Natl. Acad. Sci. USA 105, 16466-16471 (2008).

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