Episode suggestion: advanced content on editing models

[adamkucharski]

As we build up options for easier-to-edit {odin} versions of the scenarios in {epidemics}, it would eventually be useful to have an advanced episode for learners who'd like to tweak the models (as this is a request we get from many who interact with {epidemics}. Note this {odin} option wouldn't change any of the other tutorials, as model_default would keep the same inputs and outputs. The only difference would be the model code it points to, and a nicer interface to make tweaks and recompile the mnodel.

In particular, we've narrowed down the conceptual list of potential model edits in this walkthrough for {epidemics}. This could be a useful breakdown for learners, to show many changes are actually just the same thing from a conceptual point of view.

Here's the list of what we thought would cover most things people would need out of a tweaked model:

• Adding or removing model parameters. E.g. adding a uniform, age-independent, background mortality rate that is unrelated to the epidemic itself, or reparameterising $R_0$ and $beta$ inside model equations.
• Modifying compartmental flows without changing the actual compartments. E.g. adding births/deaths, immigration, zoonosis, waning immunity
• Modifying which parameters can be time dependent. E.g. change in infectious period with better isolation or treatment.
• Group-specific infection parameters. E.g. vaccination targeted at certain ages.
• Adding epidemiological compartments. E.g. more complex vaccination or natural history.
• Changing vaccination rates over time. E.g. catch up or pulse vaccination - this was a special category because need to make sure numbers add up sensibly, and vaccines available can be tracked (i.e. when they're used up, can't vaccinate more).