Call list quality should be a minor factor in determining agent productivity as measured by talk time, but may be a major factor in achieving real business benefit.

Call lists contain the phone number of individual members of your targeted audience, along with additional information to support the anticipated dialogue.  The key factor to consider is the age of the list.  As noted under hit rates above, an aging call list will have a significantly higher percentage of unavailable numbers than a freshly compiled call list.  With some pacing algorithms, such as preview dialing, agent productivity will be lost on dial attempts to numbers which are no longer in service.  If using predictive dialing, these calls will typically not be presented to your agents, although they will lower your hit rate.  Impact to agent productivity, if any, is then a question of the effectiveness of the predictive dialing algorithm under these lower hit rates.

The key issue for call list quality is not impact on agent talk time, but rather who they spend the time with.  This is particularly challenging with sales promotions for new customers.  In the comics, it's amusing when the landscaping firm is offering their services to people who live in an apartment building.  In real life, it is both an annoyance to the called party, and a waste of your agent's talk time.