forecasting-ch21-supply-chainlisted

# Chapter 21: The Bullwhip ## Scope and intake Use when inventory decisions, bullwhip amplification or intermittent demand need forecast-policy evaluation. Do not use for choosing a supply-chain policy from forecast MAE alone while ignoring lead times and shortage costs. Ask only for unresolved material inputs: Are zeros true zero demand or stockouts? What lead time and review cadence apply? Are backlogs allowed? What underage/overage costs matter? Is end-customer demand visible upstream? ## Input contract and additional evidence A regular demand series, zeros allowed. Declare the replenishment `lead_time` and `review_period` in periods of the series, the target cycle `service_level`, and the shortage and excess costs. Sales recorded during stockouts understate demand; say so in `source` if that is what the file holds. Minimal **format illustration**, not sufficient training data: ```csv timestamp,target 2010-01-01,0 2010-02-01,3 2010-03-01,0 2010-04-01,7 ``` ## Executable interface Exact CLI columns: `timestamp,target`. For the demand forecast itself the chapter 12 engine's `intermittent` pool (Croston, SBA, TSB, ADIDA, IMAPA scored on RMSSE) is the validated route; this chapter's tool takes the forecast into a stocking policy. Supported method controls: `as_of, backorder_cost, bootstrap_window, echelons, frequency, holding_cost, horizon, lead_time, overage_cost, review_period, samples, season, seed, service_level, underage_cost`. The tool produces pre-update Crost