Households devote different shares to dairy, grains, meats, and produce. We derive weights from household expenditure surveys and anonymized retailer mixes, then refresh them periodically to reflect changing habits. Sensitivity checks probe alternative schemes, showing which conclusions persist across reasonable assumptions, and where caution is warranted when interpreting week‑to‑week noise versus durable structural shifts.
Discounts and feature displays can whipsaw measured prices. We tag promotions, apply price‑matching rules, and consider quality adjustments when recipes, sizes, or sourcing materially change. For temporary unavailability, we impute within category using nearest neighbors, while clearly labeling imputed points, so analysts never mistake engineered continuity for genuine market calm or distress.
Markets evolve, and baskets must adapt. Chain linking lets weights update without introducing artificial breaks, while change‑point detection flags sudden structural moves for careful review. We document every join, threshold, and exception, enabling peers to replicate results and suggest improvements that strengthen reliability across turbulent periods and stable stretches alike.
All Rights Reserved.