Rationalizing Assortments

Some of the SKUs in every store do not contribute much to revenue and/or profitability. It would be nice to replace them with other SKUs with better prospects. To do this, two important and related questions need to be answered.

1. How can we evaluate an individual SKU's importance to the business?
2. The "worst SKU" list may differ quite a bit from store to store but the retailer may not be able to rationalize the assortment store by store. How do we go from a "worst SKU" list for each store to (say) 5-10 "worst SKU" lists that can be used for the whole chain by mapping each store to one of the 5-10 lists?