Nature Physics can have a nice, dry sense of humour - here is a plot from the "Correspondence to the Editor" of the November issue, "Conference registration: how people react to a deadline":
Source: Alfi, Parisi, Pietronero, Nature Physics 3, 746 (2007)
Valentina Alfi, Giorgio Parisi and Luciano Pietronero have analysed the distribution of registrations for two conferences (red triangles and blue circles in the main figure), and after a normalisation with respect to the total number of participants, they can describe this distribution by a simple model, assuming that the "pressure to register" is inversely proportional to the time left before the deadline - that's the solid line.
This same simple model seems not work for the distribution of the payment of the conference fee - the dashed line in the inset. However, since the registration is reversible, while the payment is not, there may be a tendency to postpone the payment until closer to the deadline. Describing this tendency to postpone with a Boltzmann factor, the model can also fit distribution of payments very well - that's the solid line in the inset.
Alfi, Parisi and Pietronero conclude, "People’s behaviour around a deadline does indeed seem to be universal. If the action is reversible ..., the pressure to do it is inversely proportional to the available time before the deadline. For an irreversible action ..., there is a tendency to postpone it until even closer to the deadline, which can be described by a utility function." And they even come up with a rule of thumb to estimate the final number of participants "that may be useful for organisers of future events": Just extrapolate the initial linear behaviour and multiply it by three.
People can behave so predictably!
Source: Nature Physics 3, 746 (2007), doi:10.1038/nphys761 (alas, subscription required for the full text)