  In a recent letter, Barabasi claims that the dynamics of a number of human
activities are scale-free [1]. He specifically reports that the probability
distribution of time intervals tau between consecutive e-mails sent by a single
user and time delays for e-mail replies follow a power-law with an exponent -1,
and proposes a priority-queuing process as an explanation of the bursty nature
of human activity. Here, we quantitatively demonstrate that the reported
power-law distributions are solely an artifact of the analysis of the empirical
data and that the proposed model is not representative of e-mail communication
patterns.
