  A number of human activities exhibit a bursty pattern, namely periods of very
high activity that are followed by rest periods. Records of this process
generate time series of events whose inter-event times follow a probability
distribution that displays a fat tail. The grounds for such phenomenon are not
yet clearly understood. In the present work we use the freely available
Wikipedia's editing records to tackle this question by measuring the level of
burstiness, as well as the memory effect of the editing tasks performed by
different editors in different pages. Our main finding is that, even though the
editing activity is conditioned by the circadian 24 hour cycle, the conditional
probability of an activity of a given duration at a given time of the day is
independent from the latter. This suggests that the human activity seems to be
related to the high "cost" of starting an action as opposed to the much lower
"cost" of continuing that action.
