Note that these rates are lower than those estimated using traditional ABC methods (see again the exhibit “Doing ABC the Traditional Way”). The reason for this difference becomes obvious when we recalculate the quarterly cost of performing the customer service activities. In the exhibit “The Impact of Practical Capacity,” time-driven ABC analysis reveals that only 83% of the practical capacity (578,600 of the 700,000 minutes) of the resources supplied during the quarter has been used for productive work, and hence, only about 83% of the total expenses of $560,000 were assigned to customers or products during this period. This takes care of the technical drawback of traditional ABC systems we mentioned earlier—the fact that surveyed employees respond as if their practical capacity were always fully utilized.