Figure 2

Relative probabilities (\(f_{\mathrm{FF}}(g,t)\), \(f_{\mathrm{FM}}(g,t)\), \(f_{\mathrm{MF}}(g,t)\), and \(f_{ \mathrm{MM}}(g,t)\)) of the four possible ways of interaction between same or different gender caller–callee pairs as a function of the call duration (in seconds) for six different age groups of callers, presented as panels of (A) 21–25, (B) 31–35, (C) 41–45, (D) 51–55, (E) 61–65, and (F) 71–75 years old. The relative ranking of these four possibilities is dependent on the age of the caller and the duration of calls