Historical prices, cart composition, inventory snapshots, supplier lead times, competitor crawls, page engagement, and weather together sketch tomorrow’s checkout. We normalize currencies, align time zones, and engineer lagged deltas that capture momentum and mean reversion. Careful encoding of holidays, paydays, and local events prevents misleading spikes and strengthens generalization across categories.
Gradient‑boosted trees tame tabular heterogeneity, while sequence models like LSTMs and temporal transformers track evolving interactions between items in a cart. Hierarchical forecasting borrows strength across categories, and probabilistic outputs capture uncertainty. We prefer humble baselines first, then iterate, comparing speed, accuracy, explainability, and operational cost under real traffic.
Beyond easy averages, we rely on rolling backtests that mirror production delays, using WAPE, MAPE, pinball loss for quantiles, and calibration curves. We stratify by basket size and volatility, penalize overconfidence, and visualize impact on margin, conversion, and price perception to align model success with customer outcomes.