Nor is there a guarantee that the extra modeling efforts are worthwhile compared to automatic software selection. Regression can be expected to improve on automatic modeling if the causal factors can be identified, accurately measured, and accurately forecast into the future. In this circumstance, regression can provide valuable additional information about the forces that drive sales (or other dependent variables) and how sales behavior can be influenced in the future. Nevertheless, it is always a good idea to compare the regression forecasts to that of an automatic model, both to compare forecast accuracy as well as to learn from the similarity or divergence of the forecasts themselves.
A last word of advice to the many Excel users out there: while Excel does have a regression capability, it is extremely limited in comparison to commercial forecasting packages. If regression analysis is to be a significant part of your organization’s forecasting efforts, investment in such a commercial package is highly recommended.