  We show that three basic actor characteristics, namely normalized
reciprocity, three cycles, and triplets, can be expressed using an unified
framework that is based on computing the similarity index between two sets
associated with the actor: the set of her/his friends and the set of those
considering her/him as a friend. These metrics are extended to multiplex
networks and then computed for two friendship networks generated by collecting
data from two groups of undergraduate students. We found that in offline
communication strong and weak ties are (almost) equally presented, while in
online communication weak ties are dominant. Moreover, weak ties are much less
reciprocal than strong ties. However, across different layers of the multiplex
network reciprocities are preserved, while triads (measured with normalized
three cycles and triplets) are not significant.
