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

<p>Fig 1 illustrates definitions of social relation concepts. <i>The Diversity</i> is defined as the number of different social roles (e.g. friend, brother, mother), <i>The Network Size</i> is defined as the number of social ties (all arrows in the figure), <i>The Tie Strength</i> is defined as a continuum of closeness in a relationship ranging from weak ties to strong ties (Thickness of arrow). <i>The Reciprocity</i> 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).</p>