While combining is useful whenever more than one forecasts for the outcome are available, the approach is particularly valuable if
- Many forecasts from evidence-based methods are available.
- The forecasts draw upon different methods and data.
- There is uncertainty about which method is most accurate.
These conditions perfectly apply to election forecasting. First,there are many evidence-based methods for predicting election outcomes. Second, these methods often rely on different data. Third, in most situations, it is difficult to determine a priori which method will provide the best forecast at a given time in an election cycle.