David A. Tanzer, August 2020

In the preceding posts, we introduced compartmental models, leading to the SEIR model, which is used for epidemics like Covid. The discussion there, however, was structural and qualitative. In this unit, we take the next step with these models, which is to analyze their dynamics – this will account for the rates at which the epidemic “moves” individuals from one compartment to another. What we are headed towards are the rate equations, a system of differential equations which can be used to model and simulate the time evolution of the epidemic.