The authors justify their bSZ term:

“Mass-action incidence specifies that an average member of the population makes contact sufficient to transmit infection with bN others per unit time, where N is the total population without infection. In this case, the infection is zombification. The probability that a random contact by a zombie is made with a susceptible is S/N; thus, the number of new zombies through this transmission process is:

bN(S/N)Z = bSZ.”

The model is also extended in a straightforward manner to consider latent infection, quarantine, and treatment.

And I’m glad you’ll be safe — if there’s a zombie apocalypse, there will still be good OR blogs! (-:

]]>I’m not sure the zombification term (bSZ) should be quadratic, but I’m almost positive that in the equation for S’ the first term should be pS and not a constant P. No females, no births. (I’ve been told – by females – that the males are optional, if not vestigial.)

Do zombies die (starve) if they run out of humans? If so, a predator-prey model might make more sense. (I worked on programming one of those in a previous millenium.)

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