Plotting Your Data

It is always a good idea to plot your data, especially if you are only working with one series:

  1. From the menus choose:

    Analyze > Forecasting > Sequence Charts...

    Figure 1. Sequence Charts dialog box
    Sequence Charts dialog box
  2. Select Sales of Men's Clothing and move it into the Variables list.
  3. Select Date and move it into the Time Axis Labels box.
  4. Click OK.
Figure 2. Sales of men's clothing (in U.S. dollars)
Sales of men's clothing (in U.S. dollars)

The series exhibits numerous peaks, many of which appear to be equally spaced, as well as a clear upward trend. The equally spaced peaks suggests the presence of a periodic component to the time series. Given the seasonal nature of sales, with highs typically occurring during the holiday season, you should not be surprised to find an annual seasonal component to the data.

There are also peaks that do not appear to be part of the seasonal pattern and which represent significant deviations from the neighboring data points. These points may be outliers, which can and should be addressed by the Expert Modeler.

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