Process Interactions

Project Management Process Groups are linked by the objectives they produce. The output of one process generally becomes an input to another process or is a deliverable of the project. The Planning Process Group provides the Executing Process Group a documented project management plan and project scope statement, and often updates the project management plan as the project progresses. In addition, the Process Groups are seldom either discrete or one-time events; they are overlapping activities that occur at varying levels of intensity throughout the project. Figure 3-11 illustrates how the Process Groups interact and the level of overlap at varying times within a project. If the project is divided into phases, the Process Groups interact within a project phase and also may cross the project phases.

Among the Process Groups and their processes, the process outputs are related and have an impact on the other Process Groups. For example, closing a design phase requires customer acceptance of the design document. Then, the design document defines the product description for the ensuing Executing Process Group. When a project is divided into phases, the Process Groups are normally repeated within each phase throughout the project's life to effectively drive the project to completion. The Process Groups and their relationships are illustrated in Figure 3-12.

However, just as not all of the processes will be needed on all projects, not all of the interactions will apply to all projects or project phases. For example:

• Projects that are dependent upon unique resources (e.g., commercial software development and biopharmaceuticals) can define roles and responsibilities prior to scope definition, since what can be done is dependent on who is available to do it.

• Some process inputs are predefined as constraints. For example, management can specify a target completion date rather than allowing that date to be determined by the planning process. An imposed completion date will often require scheduling backward from that date and can increase project risk, add cost, and compromise quality, or, in extreme cases, require a significant change in scope.