SIR Model of an Epidemic

[@rebeccaakunzirwe8894]

Thank you so much!

[@javierzuniga]

Nice video! Here is a suggestion. I think the reason why you divide beta by N is more subtle than a matter of units. Why do you divide by N and not any other magnitude with "persons" as units? Here is a possible answer. The beta you are talking about can be thought as the average number of interactions in the population per unit of time times the probability of an interaction between a susceptible person and an infected person resulting in an infection (again per unit of time). When dividing by N, you can think of the average turning now into the probability of two people interacting in that population. Beta over N is then the product of these two probabilities, which in other version of this model is the definition they give to "beta".

[@mzag]

I agree with Javier Z that he is oversimplifying by simply using units to justify the division by N. Another way to think of this as a probability is that the division by N "dilutes" the effectiveness of the interaction. In other words the probability of one of the susceptible people (from S) meeting an infected person can be thought of as the fraction I/N, (the proportion of the infected people in the whole population). Then the term "beta" term represents the chance of actually passing on the disease, given that interaction.

[@kayan5513]

thanks for this helpful video