1. Pull each retailer source. Syndicated feeds like SPINS and IRI, retailer EDI files, portal exports from Target, Walmart, Ulta. The flow ingests each.
2. Standardize the SKU and the retailer. Retailer SKU codes map to your internal SKU. Each retailer name maps to one canonical record. The downstream math joins cleanly.
3. Pull the sell-in side. POs from NetSuite or your wholesale system. Sell-in is the denominator the sell-through number depends on.
4. Calculate sell-through. Units sold through to consumers divided by units sold in to the retailer, per SKU, per retailer, per week.
5. Split base vs incremental. Promo lift gets isolated using the promo calendar. Base trend stays clean, incremental gets attributed to the campaign.
6. Layer in year-over-year. Same week prior year as the comparison anchor. Account for new launches and discontinued SKUs so the comparison is fair.
7. Output the report. Weekly roll-up, retailer-level detail, SKU-level dig, optional Slack alert when sell-through drops below threshold at any major account.