Building and training the forecast model
We are going to use the car sales for the years 2012 to 2015 to design and train the time-series forecast model. We saw in the previous section that this data has autocorrelation. The steps for designing the model are as follows:
- Calculate the moving average for two quarter periods.
- Get the center moving average of the preceding step.
- Calculate the separation between the quarter sales and the center moving average for each record. This separation between the quarter sales and center moving average is the fluctuation of sales over time.
- Get the seasonal trend for each record by averaging the fluctuation for each quarter.
- Compute the trend with the regression line of the quarterly sales.
- Calculate the forecast by multiplying the season trend by the regression for each record.
Calculate the moving average and the center moving average for the data to get the chart shown in Figure 13.4. The center moving average...