When the scheduling objective is to minimize total cost
(surrogated by staff size), an optimal schedule must ensure that
sufficient agents are assigned on each interval to satisfy a composite
service level requirement for each week of the relevant
scheduling period. Alternatively, when the staff size is specified,
the service level requirement can be iteratively adjusted until the
predetermined number of agents is employed in the optimal
solution. For scheduling purposes, we narrowly define service level
as the probability that a random customer will not wait more than a specified time for agent contact