Trend and Seasonality

In the last part of this book, we present some elementary methods to deal with time series data. This type of data has already appeared in Chaps. 1 and 2. The example uses monthly sales data of cold weather gear. The analysis is mostly graphical, based on a linear trend with multiplicative seasonals. This provides a simple model for describing the past behavior of the data and for forecasting the values for the next year.