Summary
In this chapter, you first learned how to add the default holidays for a country and then went a bit deeper by adding in any state or province holidays. After that, you learned how to add custom holidays and expanded this technique to adjust for holidays that span multiple days. Finally, you learned what regularization is and how it is used to control overfitting, and how to apply it globally to all holidays in your model or more granularly by specifying different regularization for each individual holiday.
Holidays often cause massive spikes in time series and ignoring their effects will cause Prophet to perform very poorly in its forecast results. The tools in this chapter will allow your models to accommodate these external events and provide a way to predict the effects running into the future.
In the next chapter, we'll look at the different growth modes available in Prophet. So far, all our models have had linear growth but that may not be the only mode you...
