Examining Your Data
It is always a good idea to have a feel for the nature of your data before building a model. Does the data exhibit seasonal variations? Although the Expert Modeler will automatically find the best seasonal or non-seasonal model for each series, you can often obtain faster results by limiting the search to non-seasonal models when seasonality is not present in your data. Without examining the data for each of the 85 local markets, we can get a rough picture by plotting the total number of subscribers over all markets.
- From the menus choose:
Figure 1. Sequence Charts dialog box 
- Select Total Number of Subscribers and move it into the Variables list.
- Select Date and move it into the Time Axis Labels box.
- Click OK.
The series exhibits a very smooth upward trend with no hint of seasonal variations. There might be individual series with seasonality, but it appears that seasonality is not a prominent feature of the data in general. Of course you should inspect each of the series before ruling out seasonal models. You can then separate out series exhibiting seasonality and model them separately. In the present case, inspection of the 85 series would show that none exhibit seasonality.