Stochastic dynamics and a power law for measles variability

Since the discovery of a power law scaling between the mean and variance of natural populations, this phenomenon has been observed for a variety of sp ecies. Here, we show that the same form of power law scaling also occurs in measles case reports in England and Wales. Remarkably this power law holds over four orders of magnitude. We consider how the natural experiment of v accination affects the slope of the power law By examining simple generic m odels, we are able to predict the effects of stochasticity and coupling and we propose a new phenomenon associated with the critical community size.