Table 1. Definition of the degree-block variables.

Degree-block variable	Definition
	Degree, i.e. the number of connections of a subpopulation
	Number of subpopulations with degree k
	Individuals resident in subpopulations of degree k
	Individuals resident in subpopulations of degree k located in subpopulation of degree k′
	Length of stay of individuals at subpopulations with degree k
	Number of individuals leaving a subpopulation of degree k to a subpopulation of degree k′
	Leaving rate of travellers from subpopulations of degree k to subpopulations of degree k′
σk	Total leaving rate out from subpopulations of degree k
	Total volume of people travelling on a connection between subpopulations of degree k and subpopulations of degree k′