Figure 3

Reciprocation is more bursty than non-reciprocation in human communication, and varies across channels. Distribution \(p(\Delta t)\) of the time gap Δt (in days) within (non-)reciprocations (left column), and distribution \(p(B)\) of the time gap burstiness B (right column), both over links of all communication channels. Mean values \(\langle \Delta t \rangle \) and \(\langle B \rangle \) are marked by dashed lines (same colors as corresponding histograms). Reciprocations seem to be faster, showing smaller time gaps than non-reciprocations, for conversation channels (calls, sms, msg, emails), while the opposite holds for Twitter. Reciprocal communication is significantly more bursty (non-homogeneous) than non-reciprocity for sms, msg and email, and becomes less so for calls and the broadcasting channels retweets and mentions. We compute statistical significance of the difference between two distributions via a Kolmogorov-Smirnov (KS) 2-sample test; p-values (pval) <0.01 are deemed significant (green, otherwise red)