RMSE and large misses

A useful forecast starts with a clear question and a trustworthy history. This short lesson explains rmse and large misses in terms a planner can apply.

Practitioner lens

For rmse and large misses, inspect the history for stockouts, promotions, calendar changes and missing periods. Observed sales can differ from the demand customers actually wanted.

First experiment

Draw the series before fitting a model; mark missing periods, stockouts, promotions and calendar changes.

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