Summary

In this chapter, you learned a generalized method to add any additional regressors beyond the holidays, which you learned how to add earlier. You learned that adding both binary regressors, such as weather conditions, and continuous regressors, such as temperature, use the same add_regressor method. You also learned how to use the regressor_coefficients function in Prophet's utilities package to inspect the effects of your additional regressors.

Although you may now want to add all sorts of extra regressors to your forecasts, you also learned that Prophet requires all additional regressors to have defined values going into the future or else there's no information to inform a forecast. This is why we only forecasted 2 weeks out when using weather data.

In the next chapter, we are going to look at how Prophet handles outliers and how you can exert greater control over the process yourself.