In Variable, enter a column of numeric data that were collected at regular intervals and recorded in time order. If your data are in multiple columns (for example, you have data for each year in a separate column), you must stack the data into a single column.
In this worksheet, Sales contains the number of computers that are sold each month.
C1 |
---|
Sales |
195000 |
213330 |
208005 |
249000 |
237040 |
The weights adjust the amount of smoothing by defining how each component reacts to current conditions. Usually, you want to smooth the data enough to reduce the noise (irregular fluctuations) so that the pattern is more apparent. However, don't smooth the data so much that you lose important details.
If you do not know good weights, select Optimal ARIMA. Then, you can increase or decrease the weight after you examine the time series plot. Lower weights produce a smoother line, and higher weights produce a less smooth line. Use smaller weights for noisy data so that the smoothed values don't fluctuate with the noise.
Complete the following steps to generate forecasts for your time series.
If you enter a value, Minitab uses only the data up to that row number for the forecasts. The forecast values differ from the fits because Minitab uses all of the data to calculate the fits.