Machine learning
Rossmann Sales Forecasting
Daily sales across 1,115 stores, and what actually moved the error.
Where the accuracy came from
Daily sales for 1,115 stores, forecast from history, promotions, holidays and competition data. Several regression approaches compared on the same held-out split.
The useful finding was not which model won. It was how much of the improvement came from feature engineering — encoding promotion windows, holiday proximity and competition timing — rather than from the model family. Swapping estimators moved the error a little. Getting the features right moved it a lot.