Schematic example of different assortativity levels in mixing patterns. Throughout the paper we use ε = ε
α as the parameter referring to the assortativity of the mixing pattern, since it represents the total fraction of across-groups contacts. In this scheme we show three examples of different assortativity levels. A: maximum assortativity, corresponding to no mixing between the two classes (ε
= 0); B: intermediate assortativity, i.e. a given fraction of the children contacts are directed to adults (like e.g. a random mixing scenario), the others being of the child-child type; C: no assortativity in the children age class, as all contacts established by children are directed to the adults class (ε
= 1 and thus ε = α).