Direct strategy
The direct strategy, also called the independent strategy, is a popular strategy in forecasting that uses ML. This involves forecasting each horizon independently of each other. Let’s look at a diagram first:
Figure 18.3: Direct strategy for multi-step forecasting
Next, let’s discuss the regimes in detail.
Training regime
Under the direct strategy (Figure 18.3), we train H different models, which take in the same window function but are trained to predict different timesteps in the forecast horizon. Therefore, we learn a separate set of parameters, one for each timestep in the horizon, such that all the models combined learn a direct and independent mapping from the window, W(Yt), to the forecast horizon, H.
This strategy has gained ground along with the popularity of ML-based time series forecasting. From the ML context, we can practically implement it in two ways:
- Shifting targets: Each model in the horizon is trained...