Dependencies drive the order in which activities are sequenced. Activities in most projects are performed in a sequence that is determined by the relationships between activities. Activities that depend on information from another activity are ordered so that all required information is available when the activity begins. Overlapping dependent activities, that is, starting a downstream activity before all upstream information is finalized, involves a certain amount of risk. This risk depends on the assumptions made to begin the downstream activity and the sensitivity of the downstream activity to changes in the assumptions when all upstream information is finalized.