Why use external factors in a forecast?
Forecasting business metrics is an important activity for every company. Many companies use very limited forecasting methods, such as simple spreadsheets, simple historical analysis, or simple percentage changes.
Most companies do not include external variables in its forecasting models. Many people assume past sales cause future sales. Nothing could be further from the truth. Factors in the future drive (cause) future sales. These factors are constantly changing and impact future sales, independent of past sales.
This can lead to uniformed, limited or poor business decisions because managers do not have an accurate measure of where the business is and where it is going – or what is causing it. The future looks more different every day.
Including exogenous variables can improve forecast accuracy and confidence because the external factors actually drive (cause) the dependent variable. For example, hot weather increases ice cream sales. Or, higher interest rates reduces consumer spending.
Many time series forecast confidence intervals spread very wide in the future time period, which reduces the usefulness of the forecast. A simple best guess could be as good.
With more accurate forecasts, business managers and planners can make better plans and be more confident in their decisions.
Use external factors in your forecast methods to get more accurate forecasts and be more confident in your planning.
More accurate forecasting enables proactive business decisions and actions. Do not be reactive and wait for the problem or opportunity to show. Do not simply hope the past repeats itself. Use better forecasting to increase the gain or decrease the loss of the situation.