It appears most of our disagreements stem from different ways one could compose a model – and indeed, probably different approaches to model building. I very rarely focus on analytical results, so I’m often a fan of more complex, subdivided model structures, and admittedly rather obsessed with parameter choices, because when it comes down to it, most of my results are numerical.

To address some of your comments.

1. Admittedly, there is the “We got him, and he got back up” – usually the result of not aiming for the head . I’d just consider this someone “staying” in the Z class, rather than going from Z to R back to Z. But yeah, that’s philosophical.

2. Yeah, I understand your thinking there. But for every Shaun of the Dead’s smooth cleanup, there’s a “Battle of Yonkers”-scale fiasco. I think it would be an interesting sensitivity analysis to have beta vary over a range of values during the impulsive eradication periods, to see how much human casualties during the eradication effect the results – and what the projected cost of the campaigns will be.

Thanks very much for your comments, and I enjoyed reading your paper. For all the parts we disagree on, it is on Zombies, which makes it automatically pretty great in my book.

However, to address your points:

1. In the basic model you’re right: when zombies are killed, they go to the
dead (removed) class and can later be reanimated.

However, in the final intervention scenario (what we call impulsive
eradication), the zombies are destroyed and do not return to the removed
class.

We were thinking that you might kill a zombie that can then come back to
life (as Shaun does with his car in Shaun of the Dead) but also considered
the case where you can kill the zombie for good.

2. For the pulsed eradication, we were thinking more of the situation at the end of Shaun of the Dead, where the army wipes out zombies with very few casualties to themselves. Basically a heavy artillery scenario. So I’m not convinced that this applies.

3. I like this idea, it would be a great extension of the model.

4. Since we had analytic results, the parameter values are illustrative (we tried to get a grant to go observe zombies in the wild, but for some reason it didn’t fly…). But parameter values don’t make the model run, the differential equations do. However, we included the Matlab code at the end, so anyone is welcome to copy and paste it into a program and pick different parameter values to see what happens.

And, just to be clear: it was zombie modelling from the start! No other models were adapted and we thought a lot about the choices we were making. By all means disagree with those chocies, but that’s where we were coming from.

Hope that’s helpful.

– Robert Smith?