Null model: Difference between revisions

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The '''null model''' can be a graph which matches the original in some of its structural features, but which is otherwise a random graph. The null model is used as a term of comparison, to verify whether the graph at study displays community structure or not. The most popular null model is that proposed by Newman and Girvan and consisits of a randomized version of the original graph, where edges are rewired at random, under the constraint that the expected degree of each vertex matches the degree of the vertex in the original graph.<ref>{{cite journal|last=M.E.J|first=Newman|coauthors=M.Girvan|title=Finding and evaluating community structure in networks|journal=Phys. Rev. E|year=2004|volume=69|issue=2|doi=026113}}</ref>

The null model is the basic concept behind the definition of modularity, a function which evaluates the goodness of partitions of a graph into clusters.