Even though our disease model follows simple rules, it can still produce subtle and
unexpected behavior. Such behavior is called emergence. In nature, there are
many examples of complex systems which produce emergent behavior.
Extending our model
Last time, we had a few ideas for developing the model, such as having disease immunity
wear off after a while (so recovered people become susceptible again), and adding death.
Here are the rules:
Each square represents a person.
Grey means someone is susceptible (they can get sick),
red means they are infected,
blue means they recovered, and
violet means they died.
On each turn, each infected person has a chance of infecting their susceptible neighbors.
On each turn, each infected person has a chance of recovering.
Recovered people are immune from getting sick, but their immunity wears off after a while,
and they become susceptible again.
We can use models to make claims about how disesases work, and to provide evidence
for those claims. In many cases, the best evidence will be a download of the
population health plot, along with the disease parameters
(infection rate, recovery rate, death rate, and immunity time).