TBATS for complex seasonality

Advanced forecasting should be judged by horizon, segment and decision value—not one aggregate score. This note examines tbats for complex seasonality with that evaluation discipline.

Practitioner lens

Model tbats for complex seasonality at the granularity the business needs, but inspect whether reconciliation or aggregation changes bias, variance or the shape of the predictive distribution.

First experiment

Check calibration and decision impact separately; sharp intervals are useful only when they cover at the promised rate.

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