So why is yu 'e bao falling steadily? What does that mean? Any deviation from the plans can then be rectified through some type of intervention in the operation, which itself will probably involve some replanning. Deviations because of this plan are considered via a replanning activity and also the necessary interventions made to the job centre that can (hopefully) make certain that the new plan is carried out. Eventually, however, some additional deviation from planned activity is going to be detected along with the cycle is repeated. One portion of control, then, is periodic intervention in the activities of the operation. An important decision is how this intervention takes place.