In this module, we will discuss how one needs to account for stochasticity in models if one wants to study extinction.

- Understand the difference between stochastic and deterministic models
- Know when one needs to make use of stochastic models
- Understand the concept of critical community size
- Understand how stochasticity affects ID dynamics and can lead to extinctions

Read the chapter “Stochastic Dynamics and Extinctions” in IDEMAB.

The following videos discuss some of the dynamics that can occur if one considers stochasticity and the fact that if a population drops below one infected, the pathogen goes (temporarily) extinct.

In this video from the “Epidemics MOOC”, Ottar Bjornstad discusses extinctions of hosts due to ID.

In this video from the “Epidemics MOOC”, Matt Ferrari discusses the concept of critical community size.

In this video from the “Epidemics MOOC”, Ottar Bjornstad discusses how the ecology of the host (e.g. population density and movement) affect dynamics and extinctions of ID.