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Critical Scaling for the Simple SIS Stochastic Epidemic

Probability 2007-05-23 v1

Abstract

We exhibit a scaling law for the critical SIS stochastic epidemic: If at time 0 the population consists of square root N infected and N - square root N susceptible individuals, then when time and number currently infected are both scaled by square root N, the resulting process converges, for large N, to a diffusion process related to the Feller diffusion by a change of drift. As a consequence, the rescaled size of the epidemic has a limit law that coincides with that of a first-passage time for the standard Ornstein- Uhlenbeck process. These results are the analogues for the SIS epidemic of results of Martin-Lof for the simple SIR epidemic.

Keywords

Cite

@article{arxiv.math/0512252,
  title  = {Critical Scaling for the Simple SIS Stochastic Epidemic},
  author = {R. G. Dolgoarshinnykh Steven P. Lalley},
  journal= {arXiv preprint arXiv:math/0512252},
  year   = {2007}
}
R2 v1 2026-07-22T17:28:33.322Z