Model for adoption and disadoption

[aoliveram]

Tagging @twvalente for a potential model of adoption/disadoption:

$$ P(adopt_i) = \text{logit}^{-1}(\beta_{adopt} exposure_i + \beta^{adopt} x) $$

$$ P(disadopt_i) = \text{logit}^{-1}(\beta_{disadopt} exposure_i + \beta^{disadopt} x) $$

We could also make disadoption to happen randomly.

Originally posted by @gvegayon in #46 (comment)

[aoliveram]

I'm creating this new Issue because, although in some way it's related to the Issue of the dataset in adoption/disadoption created by @twvalente, I think that we have to have a model for both processes in order to run simulations. What @gvegayon published is one option. Another option is the model in this paper https://doi.org/10.1093/pnasnexus/pgae428, that may enhance the discussion.

We should keep this in mind for further steps in the multi-diff implementation.