How does Nextail build seasonality?

To build the seasonality, data available for each week-store is taken, and weeks in which less than 30% of the stores in the cluster do not have enough data are ignored.

At least 30 weeks of data are needed to build the seasonality. If data at the subfamily-store level is not available, it is calculated at the family-store level, and if there is not enough data at that level, a flat coefficient of 1 is applied until more data is available. Weeks in which markdowns occurred are also ignored. Finally, seasonality is reapplied to forecast sales for the new product.