Fig 1. Illustration of social network size, social role diversity, social ties (tie strength, and reciprocity).

Fig 1 illustrates definitions of social relation concepts. The Diversity is defined as the number of different social roles (e.g. friend, brother, mother), The Network Size is defined as the number of social ties (all arrows in the figure), The Tie Strength is defined as a continuum of closeness in a relationship ranging from weak ties to strong ties (Thickness of arrow). The Reciprocity is defined as the mutuality in a social tie and describes a social tie between two individuals where the tie is directed both ways (bi-directional arrow).