How to Model Promotions in a Marketing Department?

If we know the promotions starten endateor properties bout it, that can probably be built into the model. But you also seem to imply that that's not always available. How can it be that organizations don't have a very clear, exact, you know, transactiona log when all their promotions happened? Yes, i would say they often have. Unless there is error your data gathering process. And timing is different important. It's not just about the price, and also competitors, information and other things. Nit to consider them as a whole.