Chapter 6: Growth Modes

So far in this book, every forecast we've built followed only one growth mode: linear. The trend sometimes had some small bends where the slope either increased or decreased, but fundamentally the trend consisted of linear segments. However, Prophet features two additional growth modes: logistic and flat.

Modeling your time series with a growth mode that is not optimal can often fit the actual data very well. But, as you'll see in this chapter, even if the fit is realistic, the future forecast can become wildly unrealistic. Sometimes the shape of the data will inform which growth mode to choose and sometimes you'll need domain knowledge and a bit of common sense. This chapter will help guide you to an appropriate selection. Furthermore, you will learn when and how to apply these different growth modes. Specifically, this chapter will cover the following:

• Applying linear growth
• Understanding the logistic function
• Saturating forecasts...