Connect the Dots

Likewise, if a certain item, category of items or price points look unfavorable overall to the merchandising group, the group may decide to eliminate them from future mailings.

However, customers on those lists that looked favorable may have been buying those items but only in small test quantities. As the circulation group rolls out those lists in the next effort (and finds similar lists), the products that were appealing to those groups will have been removed, and your results will suffer.