Looks great, thanks for sharing @bernardocaldas !
How is convergence and sampling time looking right now? Also the size of the data. These are the main elements to look at to decide I’d say.
I did try it, but it didn’t add anything, so I got rid of it, to keep the model simpler. It’s very easy to implement though (just an indicator variable), so I’d encourage trying it and see if it really makes a difference.
I know it’s important in US elections for instance, but France’s moving party definitions apparently makes it harder for the voters to attribute responsibility – unless it’s a clear, big event, like Covid for instance.
I think you can just sample MCMC once, and then do out-of-sample posterior predictions anytime new polls come out – that’s if you don’t want to rerun MCMC each time.
Hope this helps 