Category Archives: Scientific practice

Network analysis abuses of null-models

Gorka Zamora-López

Analysing and interpreting data can be a complicated procedure, a maze made of interlinked steps and traps. There are no official procedures for how one should analyse a network. As it happens in many scientific fields the “standard” approach consists of a set of habits that have been popularised in the literature – repeated over-and-over again – without always being clear why we analyse networks the way we do.

Imagine we wanted to study an anatomical brain connectivity made of \(N = 214\) cortical regions (nodes) interconnected by \(L = 4,593\) white matter fibers (a density of \(\rho = 0.201\)). Following the typical workflow in the literature we would start the analysis by measuring a few basic graph metrics such as the degree of each node \(k_i\) and their distribution \(P(k_i)\), the custering coefficient \(C\) and the average pathlength \(l\) of the network. Imagine we obtain the empirical values \(C_{emp} = 0.497\) for the clustering and \(l_{emp} = 1.918\) for the average pathlength.
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