Calendar effects and trading days

A forecast is not a promise; it is an input to a choice. This primer uses calendar effects and trading days to make that distinction concrete.

Practitioner lens

Keep the decision in view when using calendar effects and trading days. A forecast for replenishment, capacity and annual budgeting may need different horizons and different levels of aggregation.

First experiment

Record the forecast, override and outcome separately so the next review can distinguish model from judgment.

This is an original educational brief. It is a starting point for discussion, not a claim that one technique fits every supply chain.