Forecast bias is a repeated tendency to overestimate or underestimate demand. It differs from forecast error, which also includes variations that can occur without a consistent direction.
Compare forecast and actual demand over the same horizon and units. Segment the results so overestimation in one product group does not cancel underestimation in another. Check how stockouts and promotions affect the observed demand.
Investigate the cause before applying a correction factor. Review sales assumptions, data handling and forecast overrides. Monitor subsequent periods to see whether the correction reduces bias without creating a new planning problem.
Open Sources Used
This page uses open and institutional references as a frame; the final decision still belongs to the company record, threshold and owner.
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Reading adjacent decision areas keeps the topic from becoming an isolated note.